'91 740T. This has been an onging problem for months now. The car will run fine for a few weeks, then the idle stars fluctuating at stoplights and when the wife warms it up in the morning. The next day it will be back to normal and might run fine for another couple weeks before acting up again. She says it will occasionaly surge or stumble at speed as well but I haven't witnessed this problem.

I had the whole intake off about a month ago to replace the engine temp sensor, I cleaned the TB at that time and all the vacuum hoses looked fine. Also installed a new intake gasket. TPS switch clicks, but I haven't verified the switch with an ohm meter. I also put in a used power stage module at this time, since the car stopped dead on me once or twice but would immediately restart. This symptom hasn't returned.

I tried swapping an 016 AMM off a good running car today with no change. I started the car a half dozen times this afternoon and the idle was screwey every time. Unhooked the battery to clear the codes and immediately after that, the idle came back to normal? Does that 2.4 computer try and compensate for set codes? Perhaps there's no cause-and-effect there but it sure seemed like it.

I'm thinking of trying a fuel pressure regulator next. There's no fuel spilling out of the port into the intake but on perusing the FAQ this afternoon, maybe the pressure is too high?

Ideas?
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Volvo Farmer:

21 Volvos '58-'91

445-544-122-144-1800-240-740

sorry, no FWD