I have a 90 model 740 turbo sedan, car runs fine unless you get into traffic and do a lot of stopping and going, for example, I was in rush hour traffic and after about 4 miles everything opened up and traffic was flowing good but about 10 miles later my car acted like it was vapor locking and would not accelerate, it would idle though, when it finally quit it would not start and when it did it would run rough, I popped the hood and waited about ten minutes and it cranked and went home fine, I also shut my ac off when I was in traffic, the other time I let it Idle for about 15 minutes and drove it about 2 miles and it did the same thing, it has been around 100 degrees here but I would not think it should matter none of my other cars do this, also I did not think a fuel injected car could vapor lock. Also car is not showing it as being too hot gauge stays in the middle, any help would be appreciated, thanks in advance I am replacing my exhaust right now hoping I had too much backpressure.

 

I've had similar problems, and for some reason a new set of plug wires fixed it everytime. I had that problem with an 01 neon, and my 88 240. For some reason, I kind of doubt that is the case here. I would check the ignition module( I think I saw Tech refer to it as a "Power Stage"), that has been a common culprit of problems like that. I'm not sure of your particular model/equipment with regards to the ignition module, but I think it does have one. Just a thought. Good luck, friend.

 

Hey, i had a slightly smiller problem the other day. I was driving and boom the car just turned off. I stoped and it started right back up and it hasent happend since. My guess is...the fuel pump relay....maybe it gets hot and shuts off. But its just a guess. Good luck.

 

I would also look at the powerstage and speed sensor.

 

I appreciate the information, the car ran real good after a new exhaust, but the problem came back, this time though it happened while I was driving about 45 mph, no stop and go traffic, I was driving the car as normal running the speed limit and I started seeing my turbo gauge go hay wire I would accelerate and the gauge would jump around, I also noted when I pulled over the coil was very hot, our temperature has been in the lower 90's but when this happened it was up around 95 +, when it is cool I haven't had any problems, I am going to check the coil and the power stage out, hopefully I will find the problem, and after I let the car sit for about 15 minutes it started and went home fine. Its been a nice car but this intermitten problem is frustrating. Thanks for all your help. What does the power stage do on these cars. New to volvo's thanks

 

The power stage controls the spark/ignition system on these cars.You can also look at the back of the engine and see if you have a engine speed sensor.If so it would be in the top of the trans area.It looks like it is mounted in the trans but is actually mounted in the engine.If you have one and the outside sheilding is broke/missing replace the sensor.It could also cause the problem.The speed sensor controls the injector pulse and sometimes the spark as well.

 

matthewensey,
I am having the same problem with my '93 940 Turbo. I replaced the Ignition Module located in the left ftont fender near the battery. The problem still occurs. I will look at the speed sensor.



Ken

 

Alright, let us know what happens with that. I wish I/we could give more definite info, without being in a garage with tools. Keep plugging, let us know what you get.

Matthew

 

Still having a problem with the engine shutting down. I am SCARED to DEATH to drive this thing. The car just quits without warning, at any speed from idle to highway speed. What is killing me (if the car doesn't) is actually identifying the problem. After the car shuts off, it ALWAYS re-starts, making it impossible for any mechanic to trouble shoot. Again, I have replaced the ECU, speed sensor, ignition module, fuel filter, fuel pump relay, radio noise supressor relay, and cleaned the throttle body too. All connections from the harness to the ECU seem solid...no bent contacts. I cannot with clear conscience sell or trade this car in its present condition. I have exhausted all possibilities. Local Volvo dealer offered no help in addition to the parts I have already replaced. If anyone has any other ideas, I would appreciate it.

Thanks

 

Pillow, my 94 940 non turbo is doing similar. Reading the above I notice that my speed sensor plastic shielding is broken off for about 6" above the bottom. Im also guessing that it has been this way for a long time but my shut down problem has only been for the last week. If suggestions here say replacing is necessary I'll do it

It usually takes about 10 miles of driving for the first shut down and then every few blocks until I limp home.

Today I noticed 2 things; the rpm drops to zero immediately, even when coasting in Drive; I didnt pay attention to that symptom before. The other is that the fan came on in the driveway just as I got home. In about 15 seconds the engine died and the fan immediately stopped. It acted as if I disconnected the battery.

Also when it dies and Im coasting the dash warning lights dont come on right away like if I had shut off the key.

So far Ive pulled FP relay and burnished the contacts. Reseated the 25A FP fuse. No signs of overheating on the fuse block or the relay. Ive read elsewhere that the relay or the relay socket should be resoldered. There is no solder inside the relay and I havent been able to figure how to get the relay board out yet. A dealer tech said there are no solder points on a 94??!!??

Replaced fuel filter, it was original with 171K miles.

Replaced the coil (Bosch ignition) it was getting hot.

Soldered the 3 small wires attached to the + battery terminal. Soldered all connections on the radio suppression relay. Reseated all fan relay connectors. Removed the 4 prong grounding terminal on the RF inner fender just behind the ABS and wire brushed as well as DeOxit on the wire lugs. I concentrated in this area as the problem seems to have occured after I dipped the battery terminals in baking soda/water to remove acid residue. Flushed with plenty of garden hose water and put felt washers over the terminals. Coincidence?

I refuse to take it to a dealer, they have been of no help and are downright arrogant when I ask for suggestions. Also not enthused about a 15 mile trip into bad traffic areas.

Where is this power module located?

Ive reached all around the distributor and can find no wiring, how does it get its power/signal?

Are there any computer codes that can be accessed without an expensive analyzer? Im an electronic tech and have a wide range of test equipment from DVM's to digital scopes available to use.

HELP!!! Im about at the end of my rope and my wife wont get near "her" car until I can prove 1000% that it is fixed. Oh, yeah, she got towed home twice!

 

How does the engine harness look by the engine?
A massflow sensor and TPS sensor could also cause the stalling.

The power stage is located on the inside of the left side fender under the hood.
The speed sensor triggers the coil and the Dist. Is just like its name in this instance.It only transfers spark to the cylinders from the coil.

 

ZR,

I have an almost new power stage (ignition module). I replaced my with a new one (at the insisting of my mechanic). I wanted to get a used one...new one was $127.00. It was in the car less than a week. The car continued to shut down with the new part, so I put the old one back in. Of course, the part is NOT returnable. Make me an offer! I've replaced all the parts that could have been suspect. I have not replaced the fuel pump. Keep me posted on any progress you make.

Ken

 

Sounds like your mass airflow sensor is faulty. This has happened to me, too. These are expensive, but you can try to get a used one in your local junkyard or on the web. They are easy to replace. Good luck!

 

I have a 1988 740 Volvo that seems to do the same thing. When hot in stop and go traffic it will ether shut off entirely or run very poorly. I notice when it does this that the tach immediately drops to zero even when the engine is still turning. I have replaced the ignition module on the drivers fender with no improvement. My year triggers off the distributor and I am thinking that this may be causing the problem (the pickup in the dist). Someone else mentioned the air mass sensor. Our cars will go into limp home mode if you unplug the airmass sensor. It is an easy way to check a non functioning air mass sensor. So the next time this happens I will depress the wire clip and unplug the airmass sensor to eliminate this as a cause. Someone else mentioned that the intank prepump could be causing this. I cannot think how the in tank prepump could shut off the tach signal. Can it? The fuel pump relay is another possibilty too as it seems connected to the tach circuit. If anyone figures this out please let me know. I am the only one brave enough to drive this car although I tend to do it on cool days. I have also seen this problem posted in a UK forum, they haven't figured it out either.

 

Did you check the engine speed sensor?

 

I do not think my 1988 740 has a speed sensor I think that came the next year. I think mine has the distributor pick up. I did look around the engine compartment and in doing this I found a loose groung next to the distributor on the back of the head. The other ground near there did not inspire much confidence either. So I cleaned and retightened. It couldn't be that easy? I will be one happy camper if it is.

 

The easy way to find out if you have a speed sensor is to look at the back of the enigne where the trans meets the engine and see if there is a sensor on the top.

 

I found the problem with my 1988 740 thanks to this and other volo forums. It was the impulse sensor inside the distrubutor. I bought a new one from fpc groton with the two o rings and seal for the distributor. I was not going to replace the seal at first because I couldn't figure out how to get to it. With careful prying the 'washer' came off and I went to pry out the seal. It just crumbled so I am glad I replaced it. I then removed the old impulse sensor (drilled out rivits) and rivited in the new one. Car runs great no more shut offs or running poorly. I should be good for another 234k now!

 

Cool I was heading in that direction next.Then you don't have a speed sensor in the back of the block.

CONGRATS.

 

check your fuel pump relay!!