Hello helpers- I'll try to be brief. 92 740 wagon,non-turbo. Engine started stalling and dying on the way home. Made it home. It started just fine later on but soon as it reached operating temperature it bogged down and rpms dropped like a rock and it died. re-started but ran too crummy to drive. Did the obd and it threw 232 code for 02 sensor. Here's where my question for you comes in: I suspected the throttle position sensor so I tested it with my ohmmeter according to the test in the Haynes manual for a 240.I removed the connector and inserted probes on the 1st and 3rd prongs with the ignition turned on. It registered nothing. Am I on the right track? Should i just replace that tps now,or did i not do the test right? the part is about $50 from Rock Auto. Well, I tried to be brief! Thanks ! ...Tinkerbelle

If you change your PS fluid again, after you are done, move the front wheels of your car onto 3 or4 pieces of cardboard stacked up then turn your steering wheel to move the front wheels full lock from side to side several times - this will move the new fluid through your system better.

Ps - the cardboard is to let the tires slide from side to side easier

You could do this in a parking lot if there no police around to ask you what you are doing!

I did not read your whole post, but I would replace the TPS unless it is pretty new. In my experience with 4 740s, except for wear parts, the only parts I ever replaced were a couple of tie rod ends and 3 TPS.

I would keep the old one in the car as part of my spares, like the ignition parts I keep in the car as they do not take up much space.

Hi- thanks for the tip. I did hear the tps click so I think it's good for now.I need to zero in on what's making the idle wonky. How did you get by so easy on your 740's?? I replaced so many parts on mine it's mind-boggling. Not counting brakes,alternator,etc. I do carry extra relays and a fuel pressure regulator,just in case. Gotta get back to the Dog Show- why is it the Golden retrievers and Labs never win??

Does a click prove it triggers a proper spark?

I have a very good relationship with Lovering Volvo in Nashua NH.

With 3 female drivers, including my daughter who traveled form Massachusetts to Saskechewan, Edmonton twice, down the west coast, North Carolina, and several other locations for wildlife jobs, we only suffered 2 breakdowns in all those miles.

We have driven over 700K miles in 4-740s, 3-859s and now 2-XC70s and except for wear and tune up parts, this dealer has never had to replace more than one part to fix out cars.

Years ago, I had an antilock problem in our '90 744 TI - every few days, when we hit a bump, the anti-lock brakes failed - it always reset when we started the car again.

The service writer had a tech swap my brake controller with the one in his car! they also worked under the dash and in the trunk - they had the car for several days - they never found the problem and only charged me one hour's labor - I did have to put the interior panels back myself.

As for dogs, I guess good guys finish last! My wildlife daughter and her husband have 2 labs - one is trained to retrieve ducks, and the other is trained to find birds in a field. (he won't sit still enough to hunt ducks)

It's nice to have a shop that you can feel good about. Try getting that kind of service from a dealer, right? My shop is similar,and his rates are reasonable. I bought my 740 at 130,000 miles and it was not maintained well. Needed fuel pump,brake block,and cat converter right off the bat-ouch! I was not impressed. Soon after that, harmonic balancer broke, gear shift linkage needed replacement,overdrive solenoid went out, 2 timing belts,and finally a complete cylinder head replacement due to head gasket failure.I'm sure there were more,but my brain is probably blocking them out! This is why I never got around to doing much preventive maintenance.Right now it's getting a thorough cleaning,inside and out,and even under the hood. And I'm almost done waxing and buffing. Wednesday it goes into the Shop.I t does idle a bit better now after the throttle clean. But that's the history of my 740!

Hi,

Have missed an update?
How did you come out on the other side of resolving the car with your mechanic?


Phil

Hi Machine Man! Well, the culprit was..... the crank position sensor! So, yep, Blindboy was on the right track with the fraying cps wire so I gave him a thumbs up. It didn't take long for my Volvo Guy to figure it out.He said when he touched the frayed wires with the car running(and stumbling), it began to smooth out and run nicer. So it's all better now. And on to the next problem. I actually talked to him this morning about a new quirk- a steering shudder. He suggested draining out the old ps fluid and replacing it with Lucas ps fluid. So I'll do that today or tomorrow. We are having beautiful 'resort weather' here in Missouri,but it will be back to sweltering by Saturday!--- Mary

Hi Mary!

Oh Boy! Thanks for the good news and the Thumbs up for “Blindboy” as he is quite a regular on the forum.
I agree that those proximity sensors or the wiring to them, have been responsible for weird operation problems or code lights to puzzle the mind.

As for the shudder in the steering, his recommendation is a standard thing to do first as it can only help.
The pump and cylinder the rack are very simplistic by nature of their operation.
It’s tired fluid and fine particles that can mess up the function of the rotors vanes and a variable pressure control valve on the output side. It can become a shutter valve instead!

I refresh my fluid in there every year or so by just sucking some oil out as far down in the reservoir as I can reach with a hose attached to a turkey baster or suction gun that looks like a grease gun.
I find that they are a little of an overkill for the task though.
I also treat the brake fluid reservoir with a refresher treatment on about the same interval. It saves the systems fluid from holding excessive moisture and pushes the recommended two year brake bleeding exchange out more.
My theory is the fresh fluid absorbs moisture from the lower lines by contact association. Again, it can’t hurt as it’s maintenance.

I have used Lucas steering and transmission products only! Those two seem to work fine!
The engine and fuel additive products have not intrigued me so much.
One has to be on guard with branding, as it’s like a snake tonic elixirs from a wagon drummer!
Many have come and gone!

Just a personal note for our readers.

All S.A.E. oils and fuels are made having all the additives needed to do the job correctly.
The Petroleum Institute works hard with a hand in glove approach with the manufacturers of everything!
Guess where the aftermarket vendors shop but make up their own concoctions, to do what better?
Do you think NASCAR makes oil or any car products? They sell hype!
I don’t throw my money towards that labeling at all, if I can keep from it!

Thanks again Tinkerbelle for the prompt update!
As its been said on here, feedbacks do make the forum work!
AND now, it emails results! Thanks Jarrod!

Phil

Yep, one problem goes,another comes. So I drained most of the old ps fluid out with a turkey baster! Then did a refill with the Lucas ps fluid. I haven't driven it yet so I don't know if it is better or if it takes a while. The owners' manual says that no fluid exchange is necessary but wow, that old crud was murky! You're on the right track with draining some out,and re-filling. Then it will never deteriorate to the point mine got to. But this forum is great -between you guys and my regular Tech, I can always get good advice.... Thanks for checking in!-Tinkerbelle

the turkey baster method really does not do the job. get 1 to 2 gallons of fluid. disconnect the U-shaped hose where it connects to the power steering pump. connect a ~2 foot long hose to the input to the power steering pump. place a large pan on the ground and direct the disconnected U-shaped house towards that pan. connect a funnel to the added house. you will need a helper. the helper will start the engine and rotate the steering wheel from one side to the other (to fully flush the steering rack). you will continuously pour clean fluid to the funnel. if you have old fluid, it will take a gallon or two before the output fluid runs clean.

this is also the best way to clean a trans . a trans takes 3 to 4 gallons.

Hi Norfleet- thanks for your reply. I changed out most of the PS fluid per Machine Man's advice. The main problem though was that the water pump was leaking and the antifreeze was dripping onto the steering belt,thus causing the belt to get slippery and not function well. I had my regular Volvo Guy put a new water pump in for me,because it's a tricky thing to get that angle right. So now that solve both problems!... Tinkerbelle

Hi,

It sure sounded bad! Murky is yucky as one in the same?

Keep doing that over and over, a few weeks apart, until it looks more like the stuff that comes out of the bottle.
If all works and sounds good then you can do it every year or two as a maintenance item.
Check the rubber boots down on the steering rack for splits and holes.
You don’t want dirt or water getting there.

Thanks for the compliments to the BRICKBOARD enthusiasts!
Your welcome.
Happy Motoring!

Phil

Based on all that you're now saying, you may or may not have multiple problems going on. If you want to try throwing expensive parts like a new TPS and O2 sensor at it hoping to solve things then fine. I'm sure they're getting a bit long in the tooth so it's not a total waste of money, but there is more testing and thinking you can do.

If the TPS isn't clicking and you're not getting continuity between pins 1 and 2 when the throttle plate is closed then there's a problem at the TPS, plain and simple. The engine doesn't know your foot is off the gas and that it needs to try maintaining minimum idle speed with the IAC valve. The TPS switch may well be internally worn/fouled, but there's always the chance it's just out of adjustment or the throttle plate isn't able to close all the way. That's why I suggested starting with the basics. Unlike some other engines, there's nothing overly complicated about these TPS switches, they simply detect whether the throttle is closed or wide open.

Your next step should be to loosen the TPS screws and rotate it fully counter-clockwise so there's no question about the switch being able to fully close and see if it will now click. Failing that, you could try removing it to check shaft movement and test across pins 1-2 with a meter. Although not at all standard practice, some people have had limited success trying to shoot contact cleaner in past the shaft or soak them in a solvent cleaner bath and repeatedly shaking, hoping to loosen and get some of the internal grunge away from the contacts, then throughly shaking dry. In general, replacement is recommended at that stage. If the throttle body throat and plate have a tendency to get dirty then the internals of the TPS switch are all the more likely to be dirty and needing replacement.

Now any problem at the TPS switch should be a separate issue from the fuel trim trouble code you have and a possible problem with the O2 sensor. About the only way they're related is if the fuel trim can't be maintained when the ECU doesn't know it's supposed to be maintaining idle and the engine is stumbling, rocking around and about to stall, which your comments now suggest is a distinct possibility, or when the engine is racing out of control. That's why I suggested once you've verified TPS operation, to clear the trouble codes and wait for them to come back. Also note that I only say a possible problem with the O2 sensor as there are a number of other possibilities that can affect fuel trim, such as vacuum leaks. The O2 sensor is just one of a number of inputs into the fuel trim program and is a separate engine management function from maintaining idle speed.

You need to first correct the problem at the TPS before worrying about the O2 sensor. Once you've got that dealt with, I recommend you check out the FAQ here. There are two good sections that deal with the O2 sensor: 700-900 Engine Sensors and 700-900 Oxygen Sensor Diagnosis

Once you've got the TPS sorted out, if the stumbling continues then Blindboy's thought about the CPS cable as an additional problem area is worth consideration. Inspect the cable carefully for damaged/split/worn sheathing, especially where it's near the metal tubing or other wear surfaces, at the clips, at the connector, and way down by the sensor on top of the bell housing (a common spot and usually fatal there). It's not always easy to see, though. Some days you only notice the damaged cable after you've got it removed for replacement. Wrapping damaged/worn areas in foil will only help restore the electrical shielding if it's touching bare braid or grounded to the chassis. The cables should be routed so it's kept away from wear surfaces, especially the metal tubing, but the two factory installed stand off clips on the pipes are often broken or missing at this age. I use nylon tubing and zip ties to fashion my own standoffs when needed, although cheap, small zip ties may not last all that long in the harsh environment back there -the large thicker black UV-proof industrial quality zip ties last longer.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Funny, but i have a roll of that aluminum tape around here. Maybe I'll give that a try tomorrow.I really don't love the idea of buying a $160 MAF sensor.But I will if i have to.(see my previous post) thanks for your thoughts!

Ok, here's what i found out: I turned the throttle spindle and I did indeed hear a click and another click as I turned it back. I used the core from my shop towels as a stethoscope on the tps to make sure. I did not mess with the tps screws at all. I think it's good. I ran the engine then pulled the plug on the amm and there was no change in the idle. But let me ask a stupid question:The connector I'm supposed to pull is the one that has the intake air temp sensor on the end? Was that right? Tomorrow I will remove the throttle body and clean it with the proper solvent....(And, yes my Volvo tech is a real one-and he has a known good amm in his shop that he can test with. He just can't get my car into his shop til next week.) Oh also- KGV, you asked about obd codes- still has 232,and the 243 for the knock sensor that has been there since I swapped cylinder heads.

Meanwhile, back at the wrench...... Ok, Today I took off the throttle and gave it a thorough cleaning,and cleaned all nearby hoses .Started it up and it idles nice just under 1000 rpms as before. Ran it 12 minutes while giving it no gas. Did not stumble til I gave it gas,but it recovered on its own. It really does run better now,but not yet perfect. I'm ruling out the TPS and AMM. Still shows 232 code.

Good, you’re following our suggestions and making nice progress.

You say you're still getting the 2-3-2 code. I presume you’ve cleared all codes and checked that they're clear before restarting, only getting 1-1-1 codes on both the fuel side (socket 2) and ignition side (socket 6)?

If it’s idling nice now and immediately stumbles when giving it gas, be very, very suspicious of the ignition side rather than the fuel and air intake side. If the stumbling disappears at higher revs and is significantly better when the engine is hot after a good run, be extra suspicious of simple things like fouled spark plugs and old/dirty/loose ignition wires. A worn/cracked distributor cap and rotor are another gotcha area that’s easily ignored.

Again, I’ll mention you may have multiple problems going on, so do keep an open mind and go back and re-read previous thoughts here as we’ve covered a lot of possibilities.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Thanks Dave- yes, will do. I found out today I do not have an AMM! So that's definitive. I changed the coil wire and spark plug wires about 9000 miles ago,as well as rotor and spark plugs.They're fine.I may change the spark plugs though just for the heck of it.The ones in there now are the ones IPD sent me.They're ok but I remember many years ago installing the Bosch plugs and how fantastic the engine ran after that.It was strange because i have a Regina system.But a Bosch distributor. Maybe that's why the car liked them better. So, yep,thanks for the advice. I actually have an appointment next week with my regular Volvo Tech.he can take it from here.

Hi,

Are you sure you don’t have an AMM or is someone calling it a MAP sensor? They are one in the same.
If you have fuel injection from Bosch I’m pretty sure it has an air flow sensor.
It’s located right behind the air cleaner box and attached to a snorkel tube going up to the throttle plate mechanism. It has an electrical plug hooked into the top of this round box affair.

You seem to be very up to date on how your car works or at least the maintenance things that affect its performance.
With this said, I think you have realized that the cars are fairly simple to work on by yourself.

It makes me happy that you have this kind of interest and as they say in New Zealand, Good on’ya!

Phil

Hi Phil- well, My regular volvo tech said i may need a MAF sensor. When I told him i didn't see it he asked me to send pics.then he said I don't have a mass airflow sensor after all. I have what i think you're describing: intake air temp sensor.It's on the end of the electrical plug that goes into that big honkin' black tube coming out of the air filter box. Its about as big as my thumb. I have no idea whether i have Bosch fuel system or not. But we are thinking maybe it's a fuel pump issue.I may drive it tomorrow and see how it acts. But yeah, I know more about cars than most women. Trouble is, now my kids want me to fix their cars!

Sounds like rex regina..Chk the voltage coil & clean the contacts,,

So, you have something like this?

Yep ,pretty much.

But that's a K-Jetronic, and I'm pretty sure no one was expecting that in a 92...

Yes, gotta expect the unexpected with these cars.No two are alike!

HI,

You have got that right!
It's just like what I posted to you earlier.
"The 700 series were being produced at the same time and several parts were interchangeable despite every effort to screw things up!"

I will say that the one in his photo is different than what I see on the 240's!
It has the intake manifold of the K jet system, in that, it draws air from the underside where the nineties cars have a sideways throttle plate. So, it's a side draft manifold.
Differences yes, but it still does the same thing as in conveying air.

I looked over one of the other post you made and the statement you tech man said about a temperature sensor.
Temperature is a constant physics factor used within a "contained volume" that these instrument are built around.
So is the AMM or MAP and even a MAF (mass air flow) depending on how you want to think about the intake manifold as its getting filled up or measuring it up after the fact.
One is like a tire on the car. It holds "pressure" at a certain volume but if you drive the car the tire swells due to warmth. A colder tire shrinks its volume and the pressure changes and these are on charts!
The second one is like wetting your finger and then blowing on it with different amounts.
The finger senses the evaporation factor as more or less volume changes.
The Bosch uses a hot wire or film as a heated element, for the fixed wetness, that gets cooled at a certain rate.
A change in current flow measure is related to temperature and volume charts.
Others use a flap or moving vane with an electrical reading attached. Therefore it's more mechanical and more prone to its on issues!
This type above has taught a many of mechanic to go that way despite common sense!
Sprays were made for these and have screwed up the first two types!
Don't use them on a wire meter!

Scientist or "college boys" use lots of charts to define their environments, especially if, they're involved in thesis papers and journals! (:-)
When it comes down to the boiling pot or a term used there are two or more ways to skin a cat, patents get created, but their still using the same book of earth's laws!

What worries me is a "hired" mechanic throwing parts in, at my expense, to what he thinks is the most common problem. You have one of the above!
He get to sells a part, with a markup plus there diagnostic labor equals parts.
If along the way it was something simpler, It can be Easily be excess air from someplace, but you'll never know, if he finds it at the same time!
Your term of "just letting him have it" is not a good mind set for women to have!
I have heard of horror stories done to some men, just as easily!

You truly cannot test these meters except by switching in a know good one.
I have several from junkyards for about thirty dollars or less on sales!
If and when I ever change one of these, I swap them back and forth to prove it!
I never want to give up a good core in exchange for a rebuilt one.

A business mechanic will not interested in doing the above but you can if you want to keep the old one and exchange it in a few days.
Remember "time is money" and old cars are not a source of quick money from frugal owners.
Life's Lessons come in several price ranges!
Mechanics have payments for tools and equipment to keep up with.
The latest fad of new cars with computers and electronic dash gadgets with media portals are not what "driving" is suppose to be!
As the Tappet brothers would say, many Mechanics prefer for you to make a boat payment for them or go away!

If you shop the parts stores you can get a rebuilt for $100 or less with the same warranty. This is plug and play.
If you're keeping the car for love, having a spare can end you up at the same place with an option and a bargaining chip upon selling.

Phil

Hi.- Well, I think you may need to re-read my posts. I never said of my volvo tech to "just let him have it", or anything like that. He's taken care of my 740 for years. He suggested the MAF sensor but asked me to send him pictures,and when I did he determined that I do not have a MAF sensor. If I did, he has 'known good ones' in his shop that he can swap and test with.Also has the necessary relays and stuff that he can swap out,so I'm confident he will do right by me. At this point,I don't feel like I want to much more.The weather is sweltering hot now,and I'd rather just put it in the hands of someone who knows much more than me. But I still may change those spark plugs though :)

Hi,

I didn’t mean to get in on your bad side but I was speaking in a metaphor of a mindset and I apologize for using the quotation marks.
I will have to be more careful about using those things.
You can check out your last line here, as it looked like a turnover to me.
https://www.brickboard.com/RWD/volvo/1679604/740/760/780/tps_sensor_test.html

I did also read that your mechanic uses a spare sensor, so that tells me you are in better hands than I thought! I apologize again for my over worrying, for you.

I feel far you being in the heat and if you have humidity with that can be a big hindrance to go hiking or exploring into unknown territories. I’m a bit lazy myself and it why I don’t live east of Omaha, thank you very much!

Anyway I hope that in trying to explain the lack of greater results and actual differences between these instruments.

It been a man world for too long because it a matter of conquering territories inside this big business of creating more business. We need more women minded thinking in the future.
The electric car field is wide open and just look at the many ways they want to charge batteries.
They have almost got the cords fairly standardized, now, after how many years? 20+?

I think a drive over an induction plate is going to win against vandalism.
Also, it’s effortless, using a VIN from a scan under the car to start the charger!
Drive in and get green lighted. Done!
You leave the car with everything you want to carry with you, without a second chore done out in the heat or rain and snow!

Everyone wants a piece of the action without concerns of how quick things will go obsolete.
I have waited and waited by keeping my 6 240’s running for almost nothing and haven’t worn them out yet! Just two of us?
My investment in total almost equals the medium price of one new plastic & foam car or an electric car!
A Prius, that actually still has a dash to look over or I can modify!
I saw the inside of a Tesla. It has only a computer screen and it looked so empty and sterile!
Yuck for big bucks! No thank you?

The 700 series was Volvo’s attempt to lose the old and they have been experimenting ever since!
There is talk of no more combustion engines as the gadgets are where the money is made anyhow.
Some cars offer a packaged meal service in their trunks!
Maybe their after the homeless government checks?

As you know, Hide and watch out!
An electric car might be in my near future, if it settles down to some standards, a bit more!
(:-)
Good luck to you for hanging in there, Susan!

Phil

Oh, no problem Phil! It's a long thread and things get lost in translation so to speak. It is fun to see what others think about my car issues. We'll get to the bottom of it though. BTW- It's Mary ;)

Hi,

This was copied from a table in frequent asks questions.

https://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm

2-3-2* Fuel trim (lambda control) too lean or too rich at idle }If too rich: high fuel press., leaking injector } various driving problems Fuel trim (lambda control) too lean at idle Oxygen sensor

The trouble with this code it is so generic that it’s almost worthless.
The main thing is the idle mixture is too lean and thus is most likely from a hose leak.
A vacuum hose or the snorkel tube might have a TINY crack. The snorkel tube is very susceptible to these down in the volutes or a hole rubbed into the tops.
I mentioned that as being is behind the AMM and goes to the throttle.
Try to keep the sides of the tube from rubbing anything like a strut tower.
Everything has to be air tight behind the Air Mass Meter or Manifold Absolute Pressure sensor (MAP)

The AMM is likely to be a Bosch unit and will say so, on the square part facing the engine.
The most common number is a Bosch number ending in 016 on last models of the 240’s.
The 700 series were being produced at the same time and several parts were interchangeable despite every effort to screw things up!
If it’s a rebuilt one it can have another name with a sticker saying “injection labs” that is a common rebuilder.
There is no way to test these but you should pull the connector and give the pins inside it a gander for any tiny amounts of corrosion.
Look to see that they are all up at the top and even as to show that they are properly seated in their respective holes.
Just removing it and disturbing them creates a cleaning action and might temporarily cause a fix. I have had that happen on my 240’s.

As far as an oxygen sensor goes it doesn’t usually cause a stall right when you touch the gas pedal.
It’s not that fast to react. So I’m saying it throttle related and the cleaning of the throttle body can only help!
The throttle switch has to click just as the throttle opens from being a “completely closed plate” inside!
This gives the computer a heads up that conditions are about to change.
The is a transition moment to step up power and the fuel to keep it rich enough.
All idle AIR must go through the Idle Air Control valve. IAC

If the engine is running or hitting smoothly and starting quickly there is no need to suspect ignition or fuel pumps or the AMM at this time.

Squaring away the air intake, with the gas pedal movement, is the heads up and you have done good!

I definitely understand why the kids in the neighborhood or in the family want to pick your brains and skills you have acquired!
I get that quite regularly on lots of things household running related.
Face Time gets used with my in-laws that are just handy enough to handle some tools and are adventurous!

It come with the territory of being socially capable!
(:-)

Phil

Ok, so if I just loosen the 2 screws that hold it on I will be able to rotate it? I just now started the car and did not hear a click from the tps at all when I gave it gas. How audible should it be? the FAQ said next to test it with a meter on pins 1 and 2 while running to see if the idle returns to normal. By the time the idle gets rough,the engine dies. But here's one more thing: I talked to my regular Volvo Tech and he said " Mary,just replace the MAF sensor." Then he wants me to call him on Monday. It's Ok. this isn't my daily driver anymore so it's not urgent that I get this done. I'll try as many of these suggestions as I can,then I'll post back if i have any news. But thanks to everyone! this forum is so great-when I posted about my daughter's catastrophic engine problem on the Subaru forum we got no replies even after 2 months!

The screws are in elongated slots in the TPS body so the switch can be rotated back and forth for adjustment just by loosening the screws. You of course will have to re-adjust it properly once you've turned it, but if the switch isn't clicking there's really no other choice.

You're not going to hear the TPS click when the engine is running (leastwise not without a stethoscope). In quiet surroundings, with the engine not running simply turn the throttle spindle by hand to open the throttle. Just as it's opening you should hear a faint, but distinct click from the switch and it should click again as you return it back to the closed position just before it reaches the stop. If there's no click then you need to loosen and/or remove the TPS switch for more thorough checking. If you still can't get it to click then it's at that stage you use a meter to verify the switch is indeed faulty when there's no change in continuity between pins 1-2 as the switch is opened/closed.

BTW, as you have seemingly learned, when you're all done make sure the throttle cable is properly seated in the correct spindle groove otherwise the throttle can't reach the fully closed position.

Your mechanic's thought about replacing the MAF sensor (AMM to us Volvo types) is way, way too premature. If he's actually stuck his nose under the hood and knows what he's doing then I'm afraid calling him a Volvo mechanic is being a bit too generous. Yes, a failing AMM can cause stumbling, although hesitation is usually how it would better be described, but more often than not these Volvo AMM's fail outright and cause a no-start. One proper way to diagnose a bad or failing AMM when the engine won't start or is running particularly poorly is to disconnect the AMM (with the key off) and attempt a restart. This forces the ECU into what's called "limp home mode" where it ignores sensors like the AMM. If the engine now starts and runs better than before then it's the AMM, otherwise the AMM is just as likely okay and it may well be something else. An even better way to diagnose a faulty AMM is to borrow a known good working AMM and swap it in as it only takes a few minutes. There are only a couple of different AMMs used on the old B230 engines and any decent Volvo mechanic worth his salt will have known good spares on the shelf just for such occasions. As long as we're on the topic here, and as others may be following, using special MAF/AMM spray cleaner is more often than not a worthless and perhaps even fatal attempt at trying to restore funcionality in this type of AMM with a burn off heater cycle. I've learned that lesson more than once.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Take a piece of aluminum heat tape & wrap it around the CPS,,wire,,I bet thats the problem

hello Blindboy- you were right! My Volvo Tech said that when he moved that wire around,the idle straightened out and it ran fine. He's just gonna replace the sensor since it was very frayed and the part is not expensive.Nice going!

Thank you both for your replies. I did the tps test before I did the obd test.that's why I suspected that sensor.Just now I put the connector back on and started the car. Started fine,but quickly stumbled and idled super high,so I turned it off. Maybe it didn't like me probing around in there.I tried testing it on the other 2 pins as you said but still got nothing.I suppose the obd code for the 02 sensor is the culprit.

If it's now immediately stumbling and going to a high idle condition right after a cold start then that changes things. It's suggestive that the ECU either can't control idle or doesn't know it should be trying to control idle. Perhaps your initial TPS thought is valid.

For idling and stalling issues, I always like to start with the basics:

Start by making sure the TPS electrical connector is fully seated and you can hear the click of the TPS just as the throttle is beginning to open and again just as it closes. Following that, verify TPS operation and sensing using DTM 2 as I first suggested. It should not be set on the hairy edge where you barely need to encourage it to get a click. There are specs as to the gap at the throttle stop screw for the click, how to properly adjust the TPS orientation (it's different for Bosch and VDO TPS switches), also adjustment specs for the throttle spindle linkage rod and throttle cable rest position that can all affect idle mode sensing.

Make sure the IAC valve electrical connector and hoses are fully seated. To verify that it's capable of being controlled, use DTM 3 to exercise it, listening for the indicative tick-tock or using your hand to feel for the vibration of the piston rocking back and forth hitting end of travel. The IAC valve can also be removed for inspection and a light cleaning if needed, just don't soak it so that fluid gets in the motor cavity.

If the throttle body throat hasn't been cleaned in recent memory then do yourself a favour and remove it to the bench for a thorough cleaning of the throttle plate edge and adjacent throat area, also making sure the vacuum orifices are clear and the PCV hoses aren't plugged, also the flame trap (non-turbo) as you're in the same area. As long as you remove it off the manifold slowly and carefully, the gasket normally survives -you can always make a temporary one out of cereal box board if needed. At the same time, if there's any chance someone has altered adjustment of the throttle plate stop screw (as might be evidenced by missing or broken factory paint indicator on the screw head), you can re-adjust the throttle stop position (use the preferred 1/4 turn method past when it just touches and starts to open before locking it, which you can find described elsewhwere here).

With regard to the fuel trim trouble code, it may or may not be a red herring. Sometimes the Check Engine light blinks on and trouble codes are set when the engine is rocking around during a stall, or more rarely when the engine races and quickly dies. Always clear the trouble codes and wait for them to come back before getting too excited about condemning things like the O2 sensor. There are additional tests you can do with a meter to check the voltage range of the O2 sensor and also the response (a slow response is indicative of fouling on the sensor head and a possibly failing heating element).

Vacuum leaks can easily be behind fuel trim issues, so make sure that all air hoses on the intake side are fully seated, not split and that the accordioned air supply tube doesn't have a minor split in it, such as underneath.

Now having said all that, if it can start from cold without stumbling, and it's more a matter of a steadily increasing idle while the engine is warming up heading towards a racing condition, like heading upwards of 1500 rpm, then the ECT sensor goes to the top of the suspect list. See the FAQ for more information.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Wow, Dave- you sure gave me a lot to think about-and do! Night has fallen here in MO so i will try to do all the aforementioned tasks tomorrow.I'm not great with diagnostics but I'll at least try to rule some things out. Thanks again.

Ok ,after careful visual inspection I did see that when I had pulled on the throttle linkage the other day,it didn't go back to its original place,so it was opened .I hope I'm explaining this correctly. Anyway, that's what I think led to the high-idle surge when I started it. I just started it again,and it was back to starting nice,then stumbling. So I think it's either the 02 sensor or the tps sensor. Both are probably original,so it's not a bad idea to go ahead and replace both .I've tested as much as I can. The throttle and flame trap were all cleaned a few years ago when I did the head gasket.

Hi Tinkerbelle,

I'm in Dogtown in StL now. Watch your step. Overrated.

Copy and Paste: https://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm

OBD socket 2 code 2-3-2 is:

2-3-2*
Fuel trim (lambda control) too lean or too rich at idle

At idle means (we hope) not a serious air intake or exhaust imbalance as measured by the AMM on intake and 02 sensor on in the exhaust.

Did you check socket six (ignition engine control)?

Your 1992 Volvo 740 (non turbo) is Bendix Rex ignition / Regina fuel injection with the square ignition coil?

Please advice,

Buttermilk MacDuffy's Tavern

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Beh.

Try cleaning your Idle control valve. A little spray of lubricate after your done.

Well hi KGV! Been a while-still have my gold wagon.Had been running well up til the other day.I guess it was due. Yes, a Regina ignition system,although the distributor is Bosch.I think I did test pin 6 and it had nothing to say.I'll bet this 02 sensor is original so it wouldn't surprise me if its time was up.I did peruse the FAQs and still wasn't sure if I tested the TPS correctly.That's why i reached out for advice. If I'm dealing with mass air flow issues, then: Better Call Paul! Dogtown now? That means city earnings tax-yuk. Well, tomorrow I'll look under the hood and see if I can see a loose air hose or something,but I'm thinking I'm not gonna get by that easy this time..........Tink

OBD Socket 2 (fuel) Code 2-3-2 means the oxygen sensor is encountering an exhaust gas mixture that is too rich or too lean at idle.

No other fault codes in socket 2 (fuel) or 6 (ignition). Repeat the procedure in both sockets and see if any new fault codes display.

You can test the oxygen sensor on the car. The FAQ has a procedure in the Electrical Sensors article (URL in a moment). You can use a cheapo electric digital multimeter to test the + VDC lead to the single black wire oxygen sensor output. You can also test for the two wire connector heater for the oxygen sensor to see if the heater is getting power.

Do NOT test the single 02 (green on my 240) wire connector on the wire harness side using a digital multimeter.

As you responded to Dave Stevens, you indicate the thottle linkage (and throttle plate) are not closing fully. If the throttle linkage is not closing, meaning it is binding, the throttle position switch (not sensor) on Bendix is not closed. When the throttle, and, in turn, the TPS switch is closed, the idle control system turns on.

throttle plate in the throttle pivots on two nylon (?) bushings. These can wear. Yet the linkage can bind from lack of lubrication at the ball joint that connects the accelerator cable spool to the throttle. You can gentle prise open the link or drip some oil. Maybe best to clean and lube with some kind of grease.

Do you hea the TPS click when you turn the throttle cable spool to close the throttle body (with engine off!).

When TPS failed on 240, the failure was internal to the TPS as the idle control remained on when you press the gas pedal. So the engine bogs and you need a light touch to get RPMs up enough to consume the fuel.

You replaced your cylinder head, so I guess we can rule out air intake manifold leaks.

I'd hope to help you fix it. Volvo Pauly is not $$$$$$$$ and some moar $$$$ like the stealerships. I dunno how what was Brentwood (now Dean Team!) Volvo and also West County Volvo are for repair service. Ain't cheapo!

Questions?
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Woo.

Ok, no click at the tps,and no other codes except the 232.Does this mean that the 02 sensor is bad,or that it just isn't getting the signal it wants because of some other defect up the line? If that's the case, then could the 02 sensor code show up because the tps sensor is bad? (I'm reluctant to mess with the crank position sensor just yet .It's hard to get to and i want to rule out other things first.)

Hi Tinkerbelle,

https://www.brickboard.com/FAQ/700-900/EngineSensors.htm#ThrottlePositionSwitch

Summation: Yes your TPS may be failing in the way I mentioned before with the TPS failing toward the idle control system remaining ON as you accelerate.

The TPS may need to be adjusted so you get the click on throttle close engaging idle control. Yet you need to push the TPS switch to the throttle closed position for idle control to engage.

However, idle control engages, normally, when the throttle is closed and the TPS set to click to engage idle control. The linkage that connects the may have a bind as the ball joint need some lube or is worn. You indicate the throttle or linkage does not close.

Your TPS may have failed whether it needs adjustment.

Get the throttle body and TPS revolved first.

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Now onto wandering verbosity!!!! Melatonin hangover here.

You may want to limit your ideas as to the root cause for your check engine light (I guess) and OBD socket two DTC (diagnostic trouble code) 2-3-2.

Did you perform the code check again for any additional fault codes in socket 2? No fault codes, just the all's clear 1-1-1 on the Rex ignition control.

Someone like Spook may be better practiced with Bendix Rex ignition / Regina injection.

Code 2-3-2 is set when the oxygen sensor encounters a fault code.

It sounds like, in your original post, your TPS may be faulty in the way I've encountered.

The engine control system is 'forgiving'. There is a margin of compensation engine control can do when running conditions are within the optimal range.

Yet like your Bendox engine control, the Bosch engine control on my 1989+ 240's, did not report a failing TPS. The engine bogged as you described.

The idle control system remained on as I pressed the gas pedal. No fault code 2-3-2.

Yet when idle control remains on as you press the gas pedal the engine bogs. I had to flutter the gas pedal until avout 20-30 MPH.

So yes, I believe you are correct.

Don't yank that CPS! Why would you want to do so? Your engine has spark and runs (poorly). CPS is fine!

You can find the Mitchell Service wiring diagram that include a PDF page for Bendix Rex / Regina.

See the 1992 Volvo 740 Mitchell Service wiring diagram.
http://www.v8volvo.se/mekartips/volvo/index.html

On PDF page 24 of 30 is the Bendix Regina / Rex system circuit diagram.

Of the three pins at the TPS, you check pins 1 and 3 for continuity when the switch is closed.

You use a Bosch TPS I believe. The switch not the sensor (potentiometer). Looking at iPd and Tasca auto parts is inconclusive.

If you need help in person I can help yet Volvo Pauly is not distant.
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Beh.

Ignore the 2-3-2 and CPS for now, your priority is finding out why the TPS doesn't click.

As has already been mentioned, this may be because of gunk in the throttle housing and/or of maladjustment.
Adjusting the TPS before cleaning the throttle body is the wrong order. Get that done first, THEN check again for the click and adjust if still necessary.
The procedures are in the FAQ, follow them.

An audible click doesn't necessarily mean that it's making contact. Use an ohmmeter to measure between the pins. A closed switch should read near 0 ohms.

BTW, the click is faint and can only be heard in the engine bay (preferably with the engine off). Just move the throttle by hand ever so slightly and the click should be heard.

If the OBD suggests oxygen sensor, why would you change the TPS? It seems you may need a new lambda sensor- after testing perhaps?

Ian F

If Haynes says pin 1 to 3 then it’s wrong. You check TPS operation looking for continuity between the centre pin 2 (may be labelled 18 on some switches) and pin 1 at idle stop, pin 3 for WOT. The better way to test TPS functionality is at the OBD connector using DTM 2 (diagnostic test mode, see the FAQ). That way you’re checking both the switch and all the wiring connections to make sure the ECU can see it.

In any case, if it’s exactly as you say then it’s more than likely the O2 sensor if it’s idling fine after a cold start for a couple of minutes. The OBD trouble code confirms that. The ECU doesn’t use the O2 sensor until the ECT says the engine is close to reaching normal operating temperature.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now