Hello all, I just bought a 1989 volvo wagon and it seems that it has a problem that the previous owner did not mention. I first noticed this problem while driving, but it happens when I am parked in neutral as well, so I am assuming its not the transmission. The symptom is as follows.

-the car is parked in neutral (its a standard).
-I press the accelerator down a bit.
-the car begins to idle higher then it looses power, then goes back to idleing then looses power, and back and forth.
-its as if I am pressing the accelerator and releasing (like reving the engine), as in Power-No Power-Power-No Power. But I am holding the accelerator in the same position the whole time. I actually made a little movie of it that I can send or even post here.
-first I took of the distributor cap and cleaned it all out, then used an erasor (as per a mechanic) to get rid of any traces.
-this worked for a while, then the same thing.
-got a new distributor cap and wires installed ($180).
-good for one day and then, SAME THING AGAIN!
-the only thing I noticed is that at night (cooler) the car did not have this symptom, but during the day (hot NYC august sun) the car stops working.

any clues would be great. I don't really want to go back to that garage, cause I think the overcharged me. and Phil at VolvoLand (the nearest garage recommeded on this site) is on vacation for 2 weeks. I don't want to take it to just anyone if I can avoid it. any help?? thanks Dag.

Thanks to everyone who responded! Looks like I have a lot of stuff to check. If you are a fellow Brooklynite/Volvo owner, send me an email.

Was the AC on or off? How fast were you idling with your foot on the gas? How many seconds does the cycle last? If you want, try holding the rpm up from the engine bay - that way you can listen for any clicks indicating a load somewhere.
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95 854T, 88 780, 88 245

My bet is that it's either the air mass meter, the thermal sensor in the air box, or both.

The problem sounds like the fuel injection system is doing what they call "hunting". One of the many sensors your engine has may have failed or is sending the wrong information to the computer. Is the service engine light on? If so there's a computer code that can help to isolate the problem. You mentioned it runs okay when it's cold so it may be the temp sensor on the engine block or it may be the common O2 sensor that's on the header pipe under the car.

Good Luck...
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Volvos4me4ever 1989 245 271K miles still going strong

There are a couple of things to check, and hte first would be whether the fuel pump is getting the proper ground when the ign is first on and then look at hte ground when the car has been running for a while. It could be the fuel pump relay itself or the ground from the ECU to the relay that can cause what you describe. The relay is under the glovebox, so check this from the pin on the ecu to the relay. If the ground is weak, not zero ohms, then you have the very notable xxx-561 ECU ground problem. Look at the ECU behind the lower kick panel on the passenger side to see what the Bosch number is.
I've had both go bad on my '89 w/ 5-speed trans. The ecu froma scrapyard for $100 fixed mine, and $40 for the relay.
Does the upshift arrow light go flakey or intermittent when this happens? It could also be a bad or degrading rpm sensor on the flywheel (top behind the head), but most likely it's the ground problem.
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'89 245 Sportwagon, '04 V70 2.5T Sportwagon