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I recently purchased a 'slightly used' Siemens built ignition coil/amplifier (Volvo P/N: 1367438) to have as a spare for my Bendix built ignition coil/amplifier with the same Volvo P/N. When I installed it on the car to test it out I found that the engine would not rev over 4000 rpms, it just cuts out as if there was a governor installed on the engine. It does this whether the engine is under load while driving or just revving in park.
I then removed the recently purchased Siemens IC/A and reinstalled my old Bendix one. I found that the engine is still cutting out at 4000 rpms, just as it did with the Siemens one. I have never had this problem until I installed the replacement Siemens unit and there are no codes showing when I checked the #2 & #6 sockets on the OBD. Besides the engine cutting out @4000 rpms it runs and idles just fine.
Is there a 'learning curve' for the computer to adjust to a 'new' ignition coil/amplifier on a Rex/Regina system or is there something else going on? Thanks! (The vehicle is a '90 740 GL with the B230F engine)
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4000 RPM? That's far out, are you building a race car?
There are RPM limiting or governor functions in the Bosch engine management
systems.
From Volvo's ignition manual TP31397-1:
All control units are programmed with some type of speed limiting function.
EZK The ECU uses the power stage to interrupt every other plug. Usually becomes active over 6200 RPM.
On Bendix systems the ECU normally commands the power stage to reduce the ignition coil charging period, producing a weaker spark, which reduces the engines output.
Aging ECUs are likely to act up without robust filter caps, that can crap out
with old age. The ECUs must be protected from the high radio noise / RFI from the ignition.
Bill
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Having replaced the CPS 3 weeks ago and having no issues I now have a no-start condition. The engine cranks and there appears to be sufficient spark at the plug but no fuel. The fuel pump relay is good and so are the fuses and the one in-tank fuel pump on the Regina system. The no-start condition came on suddenly with no advance warning - the car was running fine, was turned off and wouldn't restart just a few minutes later. A good spare CPS & ICM were installed with no change in the condition. The FCP is good - just a few months old - and there is adequate fuel pressure on the fuel rail, just no fuel being sprayed into the cylinders. Any thoughts/suggestions? Thanks.
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I sure would suspect the radio suppression relay since you have fuel pressure at the rail. It seems that the injectors aren't pulsing
A quick way to check that on the 1990 cars is to switch the two relays (identical) on the coolant reservoir bracket for each other. If it runs than the RSR relay is not working properly to open the injectors. Reflowing the solder on the circuit board usually restores it.
You can also simply bypass the relay by removing it and inserting a jumper wire in the connector. The jumper is placed to make a connection between the two heavier gauge wires on the connector.
Randy
--
Any twenty minute job is just a broken bolt away from a three day ordeal
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Hi Heyu,
Will the engine fire with some starter spray in the intake?
Maybe the RSR failed?
The injectors get the +12 volts via the RSR
and the ground side (Switching) is via the ECU.
The Fuel relay has two separate functions:
One is to power the fuel pump via Fuse 11
Two is to power the ECU and RSR.
You can check with your meter to see what is wrong.
The Green/Red wire from the RSR pin 3 to the injectors should be a steady +12V
if that's missing
Check for +12V at RSR pin 4 (brown wire) and RSR pin 2 (blue/yellow wire)
If either relay socket has a loose pin it can become intermittent.
The Bullet connector for the RSR can fail where the neoprene or whatever
spacers disintegrate with old age and then the connector doesn't mate up
right.
Check and service connectors carefully.
Don't use solvent on bullet connectors, you can destroy the spacers.
Good luck, Bill
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if you want to try, you can open the ECU, note the capacitor values and orientation, there is a black line on them indicating which side is negative.
I'd ignore all other caps , just focus on the electrolitic ones, the ones in tiny aluminum cans. these are really cheap parts.
you can clip the capacitor just above the board and bend the new leads around a pin so they look like tiny springs, and insert them over the little wires you have left, then crimp and solder there. normlly they are pushed through the PCB and soldered from the backsde but that may require breaking the heat sink putty and replacing it. my thoughts are if you do this from the topside it may be easier. if you clip the capacitor can with snips about 1/8" above the surface of the board there should be enough left there above the circuit board to solder to.
No guarantee that will improve things but the caps can fail , they are cheap and I think if you carefully replace those it may help things. they can be checked in place using a ESR meter
https://en.wikipedia.org/wiki/ESR_meter
that may help you not need to remove the ECU from it's aluminum heat conducting case. I'm assuming they are similar to other ECU's.. If you like you may be able to get a reconditioned one from Rock auto.
The rev limiter is a new one one on me, and I'm not familiar with this rex/regina system.
The original notes indicated that the issue began with the replacemt of the transistor or power stage or what you like to call it, so trying to "fix the ECU" may be just leading the OP off in a different direction. Difficult to guess if there could be more than one issue involved in the cause of the problem.
I think if I was ready to order a rebuilt ICU you may try and if if it helps great, if not successful and things do not go well, then proceed with the order and eat that cost then. It may save a few bucks if you are successful .
possibly opening it could affect the core charge?
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Hi Amazonphil,
Thanks for your reply. I'm afraid that messing with the ECU is WAY above my paygrade! As Dirty Harry said in 'Magnum Force'; "A man has got to know his limitations." lol
If I can eliminate everything else as the cause of this problem then I will just go ahead and order a replacement one directly from Volvo. I've checked, and in the case of mine, it is still available and not much more than a remanufactured one. (Volvo calls it an 'ECM' and unfortunately it is not available through RockAuto.) Plus, my Volvo dealer owes me a discount on my next order. So, with that it will work out to be about the same as a reman one. Could be the best way to go.
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Hi,
If you have never changed the Crankshaft Position Sensor I would advise doing that first.
The ECU requires a very discrete signals. They need to of an appropriate signal strength called amplitude.
A CPS works on circuit fluctuations caused by metallic mass changes.
The flywheel has a spot that doesn’t have a hole or two so it can cause an interruption of a steady pattern.
This gap or drop out triggers out a pause or space of a “timed chain reaction.”
This varies the programed circuits that is actually firing on it own speed of repetitions of its program.
A small tweak here causes a ripple effect there, if you get what I mean.
An Input changes over the program lines, that have many specific codes within them.
These can being running simultaneously by the way.
The whole adaptive idea, is just that, reading and moving to different program lines to suit conditions based on sensors.
Most importantly as in a case of any degrading amplitude, the comparator circuitry will not recognize what might a “white noise.”
It’s a default limitation circuit that “Dirty Harry” speaks about. (:-)
This is one area that Capacitors are being used as filters to cut off erroneous or unstable frequencies.
In the signal section the use of Ceramic and Mylar capacitors are sophisticatedly the more stable component. Drying out with age is eliminated.
That little metal can is ultimately CHEAP and YES, it can be a Bane in electronics.
The speed limiter can be a programed code line, that’s easy enough, or a safety default code, tripped by
design.
So many of these units have a proven track record of reliability but the surrounding components that can receive or sends signals, are not so good are more likely to be considered
So you are right not to jump to any conclusions and stay out of that world or pay grade as you put it.
I have use that “Dirty Harry line myself or even a few of the 1960’s song lyric.
I Sure have enjoyed sharing the likes of Burt Bacharach works too!
Phil
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I traced the problem to a bad aftermarket - Beck/Arnley CPS - that I had installed in late Dec. I removed that CPS on Sunday and replaced it with an old spare Volvo CPS and the engine revving issue was immediately resolved. I have already ordered a new Volvo CPS and I should have it in a few days. Until then, I will keep the old Volvo CPS - that caused a no-start issue after only 2 1/2 years of being on the car - on the car. 'Volvo For Life'!
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the way I got ECU's to troubleshoot was to buy a 400 dollar 740. I then learned that my 88 has a different ICU than the 1990 I bought so I did what seemed reasonable to a volvo addict and bought a 1988 volvo 740 for 400 dollars.. ;-)
I took one all apart , thee 1988 so I have spares for my 88 740 wagon. the other looks good enough to fix, headliner fell , windshield cracked up but I got a windshield. it pukes oil up the dipstick. maybe plugged flame trap or oil separator. I did ok with it all Ive used lots of the parts and I like having spares to troubleshoot. it seemed like they actually went up in value over covid so I'm thinking about fixing the 1990 740 up. the headliner seems like the worst part of it. I have a 1990 240 , all that stuff is similar to the one I kept intact. problem with that is it blew the head gasket. I think Ill fix that in the springtime. the 740 developed a rather serious oil leak so I'm basically running myself in circles. Instead I'm driving my 88 ford van and it's been ok.. such is life ;-)
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The 740 I have I have owned for almost 25 years and it is near mint. I know it inside out and am not afraid to spend whatever money I need to to keep it in top condition. Most everything on it is original - including the ECU - or a Volvo Genuine part. The best way to go!
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Hi Phil,
Your email address was permanently failed, try again.
Avoid cheap electrolytics like the Plague.
See Amarin's nice write-up with details about his ECU rehabs.
You need the best long life caps you can find for ECU's.
I hope to do my ECU's later this year.
Spook has a good idea about servicing connectors.
Check the impulse sensor (They don't call it a CPS) above the flywheel.
It provides the engine RPM signal to the ECU with a pair of wires shielded and a ground. see if the harness looks OK.
I use a stiff toothbrush and 90% isopropyl alcohol to scrub out connectors,
then blow out with air, add a little dielectric silicone. Beware using strong solvents with connectors, I think that can damage bullet style connectors, such as the OBD port connectors.
I'm still wondering you have an RFI problem:
Try wrapping aluminum foil around the shield of that sensor harness and see if it changes the RPM limit. The foil will cut unwanted RFI pickup to the harness.
Service the knock sensor connector too, you don't want corrosion in connectors. That's another key input to the ECU. If you lose the knock sensor signal the engine timing is retarded 10 degrees.
Good luck, Bill
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Hi Phil,
Your email address was permanently failed, try again.
philmillwright at gmail.com
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Hi Bill,
I'm working on the premise that the problem began when I installed the 'used' ignition coil/amp yesterday because that is what happened. Until I exchanged the original IC/A with that one there were no revving issues with the engine. The crank position sensor - Volvo does call it that - was replaced just last summer. At the same time all connections were cleaned. Connections have again been cleaned today.
I'm thinking that the 'used' coil/amp was faulty and somehow messed up the ECU causing the present problem.
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Hi Heyu,
You have an odd problem.
Try the foil on the CPS harness and see what happens.
Insure that the two grounds (Brown & Black wires) on the top of the intake manifold are shiny clean, greased, and not loose in their crimps.
If you look at night when it's dark, do you see any corona or arcing in the ignition high voltage components with the engine running?
What do the plugs look like?
Good luck, Bill
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Dear heyu,
Hope you're well and stay so. To clear any transient problem, disconnect the negative battery cable clamp from the battery's negative battery terminal. This cuts power to the car and clears any transient malfunctions. NOTE: you will need the four-digit radio "code" to unlock the radio, if the radio is the factory-original item.
Wait 20 minutes and re-connect the negative battery cable to the battery. Tighten.
I'd guess that after this re-set, the engine should run as smoothly as it did, before the coil/amplifier swap.
If not, clean the wiring harness connectors to the coil/amplifier. An invisibly-thin layer of corrosion can disrupt a circuit. Corrosion acts as a resistor. So, the connection might allow current to pass up to a point, beyond which too little current passes, to maintain operation.
An aerosol corrosion-removed (Deoxit) will get into tubular wire terminals. Otherwise, take some very fine sandpaper form a tube, with the abrasive on the outside. Insert this sandpaper tube into the connector and twist a few times. That should remove enough corrosion to restore proper operation.
Hope this helps.
Yours faithfully,
Spook
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Hey Spook,
Thanks for your reply. So, I disconnected the negative cable last evening for about 30 minutes. After reconnecting the cable and starting the engine it still had the same issue. I then disconnected the negative cable again and let the car sit overnight. This morning the engine is still exhibiting the same problem. The engine idles fine and runs fine except for the fact that it won't rev beyond 4000-4500 RPMs.
On 'The Volvo Owners' Club' website they write that one of the symptoms of a bad/failing ECU is that the engine won't rev higher than 3000 RPM. They also write that when work is done on the ignition system or the negative cable is removed from the battery that it can sometimes take a while for the ECU to reset to the proper control settings. I'm hoping that that's the case here.
Before I swapped the original ignition coil/amplifier with the newer one I had no issue with the engine not revving to the normal 6200 RPM limit. All of the wiring harness connections to the coil/amp were cleaned this past summer - so that shouldn't be the issue - but I will check and clean them again later today.
If giving the ECU time to reset or cleaning the connections again doesn't solve the problem than the only thing that I can conclude is that the newer replacement coil/amp somehow messed up the ECU to the point that even removing it and reinstalling the original one cannot restore the engine to it's proper and previous running condition. What are your thoughts?
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I'd replace the TDC sensor / crankshaft position sensor or what you like to call it.
the engine shakes and the wires flex and there it a lot of oil there. I had some bad experiences with that sensor after my ladyfriend tried moving the car , reved it with the starter enguaged and bent up the thing it reads, its called the flex plate.
I straightened the flex plate with much mucking about. You can get to that by removing the aluminum brace under the bellhousing. I drilled a large hole there as well so I could see it and tweak the thing back into shape. it led to issues wiht no start and finally I found the bolts that stick out of my coil were rusty and that caused no spark. so it was two things.
once upon a time I rebuilt an engine, all went fine until I started it and it wouln't rev past 3000 or so.
I called the volvo shop I dealt with he was great. over the phone even he said straight away I know what you did, you bolted the flex plate on and got it on the wrong bolt holes. I had to pull the tranny or the engine to fix that and I was exhausted from fixing it all and frustrated so I had him pull the tranny , two hours later it was fine, I had marked it but made a mistake and got it on wrong.
I remember the same tech saying I should replace that crankshaft sensor because he said well they do fail so I' d change that for reliability.
it might be a bad ECU or ICU but the thing with those is they are expensive so if you buy one and it doesnt; get you further it can be an expense for not. If you know of a shop that fixes volvos or others with the same car that are nice it would be cool to swap theat but people may feel they dont wan tot lend theirs because it could get damaged.
usually with boards they come in a n anti static wrapped package and you can wear a static wrist strap to keep yourself grounded. what you dont want is to apply a shock like if you pet thekitty or scrub your feet in the carpe and make yourself charged then touch something and give off a zap of static. Boards can fry from that happening. you cna use a hunk of wire and ground that if you dont happen to have the right type of anti static wrist strap. Il often just consciously touch some nearby metal, doing the same. discharging myself.
quality of caps. I go here for my caps for radios he should have any you want.
https://www.justradios.com/
otherwise I get them from lee's electronics in Vancouver. the best are probably military spec. Im not sure where you can order those but maybe. mouser might have them.
In my van's ECU they were rated 16V you might put ones with a higher voltage rating. i doubt you'd see much difference , but they can fail. in old radios I use about 16V rated ones for common table sets from the 50's but other old radios with transformers use higher voltages so usually Id use 450V rated caps. most of the non electrolytic caps I use are the mylar ones I think they are rated 630 Volts but those are non electrolytics I replace anythign in a paper tube with that basically, usually hide them inside the old tube to keep it authentic looking.
in general the electrolytic are in metal cans and you have to pay attention to polarity, the non electrolytic dont really mind being hooked backwards. , electrolytic will blow up if you put them backwards and subject them to higher voltages. a bang, a puff of smoke nothing too serious but that's what happens. if you do that just look for a black line ont he outside of the can that's the negative lead.
If it were me I'd change the TDC sensor and if it's nothing with that at least it's done. also just for fun and since i have the issue maybe give the coil terminals and not just the spade connector tabs a good scrub. Id examine wires to the coil and ones you messed with , it could be that you have a spade connector and green stuff there and it's hanging on by 1 strand and moving it might cause the "last straw" issue.. I like to just use the crimp on ones but solder them and use heat shrink instead of just trusting the crimp method. often I might clip a bit of wire off and get to fresh wire and switch them then you know it's not an issue there.
rev limiter, new on me. maybe the coil can only charge so fast so they switch from two pulses to 1 pulse because then there can be more dwell time between and it's all happening pretty fast at several K RPM.
Id clean the plugs or put new, since that's not expensive , check the cap , I like to wash them in alcohol. you might find carbon tracks. plug wires are suspects too Id replace if they look origional and maybe not if they look ok I doubt it's tht but Ive seen lots of them break often near where the wire connects to the plug connector.
pull the wires out of the distributor cap look for green sometimes I find one full of green. easy to check.
if you have a timing light I;d connect it and point it into the car tape down the button so you can see it flashing.. and then watch when it dies, does the spark die too? can you see if it's happening in sync with the issue?
it sounds like an electrical issue, not fuel but i wouldn't exclude the injector pulse there are things called "noid lights" basically little lamps that ou can plug in between the injector and it's connector so you can watch them flashing , that might not be expensive , you muight just need one. others will know more about those things.
if you rev it at a standstill the motor may also rock , maybe it is a wire getting tugged not because of the RPM but maybe if the motor rocks further it's physically causing the issue then , a wire rubbing or being tugged, something like that might be the cause?
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By the way, when I thought the problem MIGHT be being caused by the ECU I contacted Chapman Motors on Vancouver Island and they said that they had one on the shelf for $175CDN. I also contacted Voluparts in Atlanta and like most times Bill Eidson replied to me. He said their price was $95USD. When I asked him what year and mileage vehicle it had come out of he said that he didn't know that. When I asked him if he could at least provide me a photo to see how it looked he said he wouldn't do that. So much for buying used electronic parts from him!
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I read above that you solved it by changing the crankshaft position sensor, That's great. I must have got the posts out of order, but anyway. we have good news.
if you like comparing things you can do a resistance check through the sensor and compare that to the new one you get and your old one.
You can also hook the leads to a meter, put it on volts and maybe with the analog feature if you have it or use an analog meter.
If you wag a screwdriver in front of the sensor and you should see it pulsing without being connected to anything else.
the flex plate has something close to 50 or 60 holes in it , then there is a space where there are no holes. the ICU might count the holes to see if it reads the right number to know if it's reading correctly. I've worked on machines that do similar with encoders, they count the pulses and there is normally an index pulse. if the computer counts the wrong number the machine goes into a fault mode. I'm not sure if a volvo computer does this, maybe.
with mine the gear on the starter has 5 teeth, it went up following the flex plate and bashed the sensor, then I had two problems , one was a bad sensor and the other was a bent up flex plate, to make things more confusing I also had that bad coil connection. all the gear bits were scattered about the flex plate area or had fallen out. I had a starter so that was quickly solved. Im starting to work on my 85 porsche 944 , it has two of these crankshaft position sensors. I dont know why it would need more than one but it seems to have 2
in a volvo I figure it really could not sense the position at all until the crank makes a revolution to see the blank section and yet they seem to start firing without needing to complete a revolution. I think maybe there is some way it pulses the injectors and sparks without having that reference during initial cranking otherwise how could it fire that soon? I did have a situation where i had solved the TDC sensing issue and the flex plate issue but it would fire at the beginning of my cranking but would not continue to run. this seemed to confirm the above theory. maybe the computer recognizing it's cranking and gives some random pulses even not knowing the position of the crank then when it sees the pattern it latches in and continues reading the sensor each revolution.
when I had a disconnected coil lead due to rust on the terminal I had this symptom. It would fire on first rev but would not start or run. i figured since it fired it must have spark but I think it only got a spark for the first revolution.
i remembered being a kid and working on cars with points style distributors, and seeing the same symptom but in that case it was something called a ballast resistor. If it blew it would fire when cranking but not run.. I dont know if earlier volvos had this ballast resistor or not. it might have been there to protect the points from sparking, or something similar. I think in those, the crank position , in reference to the key, had a bit different wiring than the run position.
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It turned out to be the new Beck/Arnley crank position sensor that I replaced on Dec. 31. I took it off a couple of days ago and reinstalled my old Volvo CPS that had caused a no-start problem a week earlier and the car now runs fine - revs right up as it should. Problem sol-ved! lol I have a new Volvo CPS coming! 'Volvo For Life'!
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