I'm desperate and broke at this point. I have a 1991 940Turbo volvo and I have had nothing but problems for the past 7 months. First, had trouble starting and one garage replaced the fule pump, did not fix and the distributer was replced as well as the throttle positioning sensor. That seemed to fix that problem a lot of $$$ later. One week later the car would not hold an idle and the fuel regulator valve was replaced. Then immediately following that the check engine light came on which indicated a knock sensor problem which I eventually replaced myself and the car ran great for 2 days. It is not falling on its face. No check engine light, no pick up, difficult idle at times. Any help would be appreciated....very frustrating!

Probably unrelated but at the same time the overdrive arrow is staying on and will not engage when the button is pressed.

at least on my old 83 GLT,when-ever the exhaust down pipe where it attachs to the turbo would get loose,the idle and accelleration would suffer, how are your exh. manifold gaskets? apparently any exhaust leak before or even after the turbo caused drivability issues on mine anyway.
--
83 242 DL -132k, 92-965-201k, 94-965-208k, 84-242 GLT-Gone, but not forgotten,83-245GLT-1'st brick (the 1'st 3 currently on the road)

Fuel, oxygen, and spark

Have you tried to run the car without its air cleaner? The air box has/had foam rubber to deaden turbo noise, it makes quite a mess when it craps out and clogs the air cleaner.

When I bought my '90 744 TI, I had some problems because one of the turbo hoses had a problem and someone with some knowledge had tricked the engine to run. It was getting enough fuel to run about 4000 RPM after the hose was repaired.
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96 855R, 95 855,854, 90 744 Ti - 343,000 Volvo miles put on 7 bricks

I haven't checked the air cleaner recently but checked it about 1 month ago during routine maintenance. I will check it again..good idea! What type of problem did you have with a turbo hose?

Thanks!

Here's the latest!

I went to the salvage yard and was able to find an overdrive relay which seemed to fix the overdrive problem or at least the arrow light is acting in accordance with the switch. Can't get the car fast enough to test overdrive yet.

I cleaned the IAC and have had a strange idle ever since. The car will have a high idle and then lower to about 500 rpm then back to about 2500 rpm then back to 500, etc.. I took the vacumm hose off of the intake that goes to the IAC from the large hose that goes into the throttle body and restricted the airflow out of the hose with my hand. I could cause a steady idle at about 750 acting as the air flow controller. Do you think the IAC is bad after cleaning?
Maybe the Throttle position sensor should be re-adjusted?

Car will still not accelerate at all? Any other ideas? I've checked and checked the hoses for leaks and a small leak may make the car run a little rough but not totally destroy the acceleration. Could it be the fuel injector relay? What does that control?

Thanks again!

Either you've killed the idle motor (unlikely) or you need to readjust the throttle valve and TPS. It's all in the FAQ.

--
alex

Thanks for everyones suggestions, keeps me thinking of things to try and sooner of later the problem will poke its head up.

I'm not sure how but the car ran lake a champ for about 1 hour of drive time yesterday and then failed with the no acceleration symptom (had to pull off the road and hobble home).

To get it to run decent I disconnected the IAC electrical connection and, although it ran rough, it did accelerate. After that I connected it back again and it ran for a while with no problem except for a slight high idle in park only. The idle in gear was spot on. After about an hour of drive time I stopped at a friends for a moment. Got back in the car to leave and sure enough the problem resurfaced. Hobbled back to his house, disconnected the IAC and the car ran fine all the way home (about 14 miles).

If the timing would have slipped, would the car miss frequently? When it runs well as above, there is no miss.

I'm electrical fittings on the harness and IAC look fine. I wonder if the ECU is going bad.

Oh yeah, the ABS light is now intermittently coming on. This started after I installed the overdrive relay....ugh!

Thanks folks! you guys are getting me smarter about this.

I don't think the garage ever cleaned the throttle body although the did put a throttle positioning switch on. Should I clean the throttle body?

Thank you very much for the input. I will replace the OD solenoid and clean the valve. This is a fantastic web site...people helping people..that's what it is all about!

Dear jjb,

Good p.m. The idle problem is almost certainly related to the Idle Air Control Valve (under the intake manifold). It needs to be cleaned. See the FAQs above, under FEATURES, for how to do this. If you are handy and have basic tools, you can do this.

The "overdrive" arrow is likely the result of a failed relay. It is likely located behind the front center console ashtray. To get at it, remove the ashtray (life up on the release bar). Remove the storage tray above the ashtray (plastic bezel around lighter pops off when pried gently on the right side). Two screws loosen the storage tray. Remove electrical connectors to the lighter and the light bar. Overdrive relay is in second row, on the right (passenger) side. It is marked VOLVO 3523804. You can get a replacement for a few $$ at a salvage yard. If that doesn't cure the problem, then the problem is in the wiring and/or the overdrive solenoid itself. Usually, a replacement relay does the job.

You need to find an independent Volvo Master Technician. The average garage does not see enough Volvos to get really expert in their repair.

Hope this helps.

Yours faithfully,

spook

Spook,

I also have the symtom of poor acceleration / power if I don't keep the speed increase very slow and steady and at around 50mph. Do you thing that is due to either the idle valve or OD relay?

JJB

Dear JJB,

Good p.m. If the overdrive relay has failed, you'll have difficulty getting past 50 mph. A dirty constant idle valve will make the car hard to start and at an extreme will cause very inconsistent engine operation.

If you have further questions about the doing of these things, keep posting. I, or someone else, will walk you through the process of fixing these things.

To do the constant idle air valve, you'll need basic socket tools (3/8 or 1/2 ratchet handle, a short extension, and metric sockets). Two hex head bolts (12 mm if I recall propertly) secure the valve. You'll need to loosen two hose clamps (requires a screwdriver), and one electrical connector (no tool needed).

The part of the IACV that you clean is the part at the other end from the electrical connector. You spray carburetor/choke cleaner (available at Wal-Mart or similar store). You'll see dark grey liquid running out. That's dirt being removed. Stop, when the part of the valve that moves, is clean. You can use a cotton swab, to accelerate the cleaning. Be Gentle!

The relay is a simple remove and replace. Any salvage yard should have one or two of these, for small $$$. If possible, go to a yard that let's you remove the item. That way you can pick a donor car with lower miles.

Hope this helps.

Yours faithfully,

spook

Spook,

Will the IAC and Relay also cause acceleration problems at low speeds. Acceleration will break down if not done very slow and smooth.

Thanks again, JJB

Dear jjb,

Good p.m. I don't think so. How many miles/Kilometers on this vehicle?

Does your car occasionally not start at all, or does it stop when running? If so, that might mean the crank/RPM sensor - on top of the transmission bell housing - is failing. This, too, is not hard to change. The part is about $30. This part should NOT be gotten at a salvage yard, unless you find a very low mileage car.

There are many possile causes of slow acceleration:
(a) transmission may need a flush
(b) fuel filter and/or pump may need replacement
(c) fuel injection relay may be faulty
(d) fuel regulator may have failed.

Hope others will comments.

Yours faithfully,

spook

Once you start the car you have to manually throttle it to keep the idle until you put it in gear at which time you don't have to manually keep the idle. While running, the car doesn't stall but it will lose so much power that it is crawling. If you try to accelerate, even moderately quick it will die and once it starts to die it seems to go straight down hill. You can quickly pump the throttle and that doesn't help the speed but the turbo boost gauge and the rpm indicates the increase but the car performs worse. If you then place the car in nuetral and pump the gas to get it "normal" and put back in gear it helps but will re-occur quickly when trying to accelerate moderately.

JJB

It has been starting although taking a few cranks to do so.

The fuel regulator / fuel filter and pump have all been replaced.
One garage check feverishly for vacuum leaks and said they fixed a number of them.

Where is the fuel injection relay?

Ugh...touch problem.

The 940 turbo has 169M miles on it.

Thanks, JJB

Throw in some leaking turbo plumbing also---

dick

The second garage said they check the turbo hoses....

I've had this to 3 garages within the last 6 months...

Thanks, JJB

Don't be afraid to get in there with a light and pull, poke and prod a little. The hose from the turbo takes a lot of abuse and some times both intake and outlet turbo hoses are totally connected. I use a mirrow and light to get behind them. Vacuum hoses at the manifold are another source of problems. The one to the fuel pressure regulator may be cracked. Also the port to the intake manifold can be coked up with carbon. Take a wire and poke and prod. Fortunately, these cars generally have a little thing that seems to cause a big problem.

Good luck and do not trust only mechanics---do your own looking and evaluating.

dick

Thanks Dick, I try to do that but I'm a bit dangerous. A little knowledge is a dangerous thing but because of folks like you, spook and others on this web site I am learning fast.

the ODB indicated a 2-3-2 code. I'll have to look that up but in the mean time I cleaned the air intake and made sure of the torque on the knock sensor.

the idle seems to be doing okay now although haven't driven it much, but any acceleration, except a gradual slow acceleration causes loss of power.

Thanks again, JJB

just take all the hoses off, wash in degreaser and inspect like your lif depnds on it...

be real carefull proding that manofold nipple its brass (so soft) and you dont want to open it out any!

better trick is to wind it out of the manafold (gently does it!) and soak it ina solvent..(zylene, tolurine, acetone whatever) then to get a twist drill of the right size and GENTLY holdign the drill in your fingers ream it out..be gentle your NOT aiming to remove any metal...)

Dear the kick inside,

Good p.m. and hope you're well. The best general purpose cleaning solvent is methyl ethyl ketone (MEK). This chemical cousin of acetone can be used safely on all metals. It will, however attack paints and most plastics, so do not use it near painted surfaces or on plastics!

It is very flammable, so should be handled just like gasoline/petrol. No open flames or sparks nearby.

It is carcinogenic, so one should wear gloves, while handling it. It is also important to ensure that there's plenty of ventilation (do not use MEK in enclosed spaces).

All this said, there are few things that cut through grease, oil, and crud, to leave an absolutely clean surface.

Hope this helps.

Yours faithfully,

spook

Here's the latest!

I went to the salvage yard and was able to find an overdrive relay which seemed to fix the overdrive problem or at least the arrow light is acting in accordance with the switch. Can't get the car fast enough to test overdrive yet.

I cleaned the IAC and have had a strange idle ever since. The car will have a high idle and then lower to about 500 rpm then back to about 2500 rpm then back to 500, etc.. I took the vacumm hose off of the intake that goes to the IAC from the large hose that goes into the throttle body and restricted the airflow out of the hose with my hand. I could cause a steady idle at about 750 acting as the air flow controller. Do you think the IAC is bad after cleaning?
Maybe the Throttle position sensor should be re-adjusted?

Car will still not accelerate at all? Any other ideas? I've checked and checked the hoses for leaks and a small leak may make the car run a little rough but not totally destroy the acceleration. Could it be the fuel injector relay? What does that control?

Thanks again!

Dear jjb,

Good p.m. Good going on the overdrive relay. I'm pretty sure you've solved that one.

The idle air contro valve may simply be shot. However, it may also have a weak connection. Check the connector for signs of corrosion. If you spot same, you can use an aerosol to clean the contacts. If you don't want to spring for that, a bit of fine steel wool will remove oxidation. If, after cleaning the contacts, you still don't get a stable idle, the IAC may be bad. You might be able to get one at the junkyard, with which to test your car.


The fuel injector relay - more formally known as the radio suppression relay - controls power to the injectors. If the relay starts to go, one would expect the engine to run rough. On many 940s, the radio suppression relay and the radiator cooling fan relay are of the same design. I am not sure where the radio suppression relay is found on your model year. Perhaps someone else will know and advise.

It is also possible that the fuel regulator (the small cylindical device mounted at the front end of the fuel rail, has failed. Here, too, one from a junkyard - if it is good - might enable you to troubleshoot the problem.

Hang in there: you're making progress.

Yours faithfully,

spook

I cleaned the IAC but not the throttle body that the throttle switch is connected to. The throttle positioning switch was replaced but don't know if they cleaned the throttle body of not.

Still have not gotten the overdrive relay but don't think that could cause the severe acceleration problems that I'm seeing even at low speeds.

Any other suggestions?

Thanks

jjb, Has anyone checked the cam timing? I had a 89, 740 that I bought at a yard sale and the timing belt was off 2 notches. When I got the cam timed, I then found a hole in the turbo hose (over 200.00) replaced that and cleaned throttle body. Still drive the car every now and then, but those two things really cured the no pick up. Just a thought. Pauli

I had the timing belt changed about 8M miles ago. I haven't had the cam timing rechecked but I think I can do that myself. When the car does have acceleration, it doesn't miss at all which is not consistent with a slipped timing belt or bad timing. Had another car that slipped a timing belt and it was an obvious miss all the time. Thanks for the suggestion and I will probably check the timing myself to make sure. thanks for the suggestion?