well i have a weird problem, the car has no power below 1700 revs......i mean i step on the pedal and nothing......it will stutter and shunt until it hits around between 1500 and 2000 rpms.......then it runs perfectly. this happens in all gears all the time......hot, cold, rainy, dry. i am baffled... i took it into the shop for a tune up.....plugs, wires, and all that entails. still does it. there is no air mass so please don't suggest that. my wife won't drive it...and i dont know what else to do. thanks

 

Check engine light?
Could be a timing issue.

 

Sounds likea low speed misfire which may be caused by a vacuum leak or even a burned valve. I'd check for the leak, and take a compression test. What did the shop tell you re the tune up?

 

You may also want to check the throttle linkage.

 

at the shop they said it didn't happen..... now i did notice that i have a serious lack of heat coming through the vents and it take a long time to heat up......i was wondering if this might be related..... where should i look for a vacuum leak? around the throttle body or where? and how would i know if i have one.....i don't hear any whistling.

 

oh and there is no check engine light

 

Theslow heat may be due to malfunctioning vents which may be vacuum related and supports a leak somewhere theory. Hard to say where to look for it... Anywhere where there are vacuum hoses, sound of air escaping.
When you say NO ENGINE LIGHT, you mean what? Never comes on at all? Or it's not triggered on by what's going on?

 

I agree to the vaccum leak. I would also check the exhaust for bad cat convertor. Check fuel pressure, the fuel pressure regulator could but sticking until it gets so much pressure built up that is finally lets go.

 

the check engine light works....it just doesnt come on for this particular problem...and by no heat... i am talking about the fact that the engine don't seem to warm up...i look at the gauge and it stays down towards the bottom of the gauge....

 

update...............replaced fpr and the car is fine........still have very low temperature air coming through the vents though......

 

after replacing the fpr....... and driving it for about an hour and a half..... i brought it home and parked it.....well guess what.....its doing it again... its like the damn pump keeps sending gas and filling up the intake.....i don't know what to do..... i thought i had it licked and now its back ... i am ready to just light the thing on fire, and when i call my volvo guy he just says its weird and he will have to think about it.....any ideas..?? why would it be fixed then a few hours later...rear its ugly head? please help....

 

Next time it does it, pull the brake booster line off. If the engine smooths out and increases revs, you're running rich. If it dies, it's lean and you have a serious vacuum leak.
If its lean, check all your vacuum lines and squirt some WD spray around your intake gaskets, air line connections etc. Once the WD spray finds teh leak it'll smooth out a bit.
If you replaced teh FPR the pump can run all day and pressure in the fuel rail will not increase above the set value, it just returns excess fuel and pressure back to the tank.

Regards, Andrew.