1990 740 turbo, auto trans, 153k

Items recently replaced: injector seals,mass air meter, main fuel pump, fuel filter, vauuum hoses.

Here is the problem (and it does not happen all the time); When driving the car and I mash the gas peddle, it won't go over 3500 rpm..it acts like it has a governor and tends to bog a little bit. If I throw it in neutral and restart the car, the problem goes away (some of the time). The problem happens if the car is hot/cold. From time to time, the problem starts at 2500rpm. All vacuum hoses replaced, no "service engine light"..this volvo starts, idles and generally drives perfect except for the above problem.

I can't help thinking its the mass air sensor I recently replaced (rebuilt from FCPgroten). The old one was definantly bad and had to be replaced......

Any ideas out there??

thanks in advance!
Mike Mulhern
Scottsdale, Arizona

Check the timing. Your t-belt may have jupmed a tooth or two. This happened to a 240 that my mechanic services. Took him a long time to figure out the problem. The timing light showed everything was normal. He had to remove the covers and manually check the timing. That engine would rev fully on the first couple tries in neutral, then it would bog out. It would also bog when attempting to accelerate. I hope this helps!
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Chris. Halifax N.S. '91 745Ti, 274K km.

Intake hose failure is common. The hose will open during boost and allow air measured by the AMM to blow out instead of into the intake manifold. Usually happens on bottom side where you cannot see it. If you look carefully when it happens, you may see a light trail of black smoke behind you. Sometimes engine twist will cause the tear to open more at some times than others, making it seem intermittant. It wasn't until I took all the hoses off and found a little blister on the inside that I realized there was a cut on the outside too, just where the clamp holds it. All hoses after the turbo are suspect.

Airbox thermostat sticking will cause failure of the mass air flow sensor. See FAQ 700/900 section for more details.


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David Hunter