98 XC 70. Had problems about a year ago - changed fuel filter and pcv system - car ran fine for 6 months or so after changing pcv system. Had problems again a few months ago. Changed front O2 sensor - car ran fine for a few weeks. Car began running rough again, finally stranding me by the side of the road. Got it towed home- would crank but would barely pull itself around the yard. Replaced the mass airflow sensor. Now it does fine for the first 3 or 4 minutes. Once it warms up, it stutters and hesitates under acceleration, especially on inclines. You can ease off the gas and then press again and it will surge forward while emitting smoke from the exhaust. Seems to get gradually worse as it gets warmer (haven't driven that far or at very high speeds since i don't want to have to get stranded again). It doesn't appear that I have any vacuum leaks, but i'm not positive. Would greatly appreciate any suggestions! My wife is Swedish and is now on the verge of hating Volvos - and I don't want that on my conscience! :-)

 

Thermostat ok?
ECT ok?

 

Thanks for the response tech. I don't think i have an ETC - Is there a way to check the thermostat, or shouldI just change it?
I've just been out driving again and it does fine for a bit, then when accelerating or on an incline it stumbles - you can either ease off the gas or floor it and it runs fine, but if you floor it tons of black smoke comes out.

 

Yes you have a ECT that is the coolant temp sensor.
If the thermostat is bad you will usually see it when you open up the housing.
Does the check engine light ciome on at all?

 

I just had to replace the ECT on our 95 850 and it exhibited similar problems. Granted they are different cars but basically the same engine. Agree with Tech, is the Check Engine light on or are there any codes stored in the computer?

Glenn

 

Thanks again a ton for the advice. And my apologies for my relative stupidity when it comes to working on cars. When i replaced the mass airflow sensor i disconected the battery for a half hour or so - the check engine light hasn't come back on since then, but i don't think i've driven the car enough for it to do so - only three or four miles. Is it ok to reset the codes this way, or is it better to have them cleared with a scanner? The temp gauge inside the car reads about 1/2 way up, which is the same as it's always been - not sure if that makes a differenence or not. I'll look at the thermostat and check on the sensor also.

 

Light came back on and I had the codes pulled again.
1. P0131 - Front O2 - low volts (just changed it)
2. P0108 - MAP/BARO - (Just changed Air Mass Meter)
3. P0243 - Turbo/Sup Wastegate - Solenoid A Malfunction
Thanks again!

 

Did you clear them before disconnecting the battery?
If not then clear them. Just disconnecting the battery won't clear the codes.

 

Thanks again for posting. I had them cleared - seems to be the same. I've been busy, so i haven't had time to check anything - but I have some time off at the end of the week so i'm hoping to work on the thermostat and the etc. In the meantime, I have been told that it wasn't good that i used an aftermarket O2 sensor. Is this a real problem?

 

I've used aftermarket O2 sensors on cars before. Some are ok, and some are not. While I have not tried it, I have heard that Volvo's do not like the aftermarket sensors and work best with the OEM type.

Glenn