I was thinking of a couple other mech. problems I have had. Rarely when I am driving on the highway, the engine won't accelerate. Sometimes I get a pulse in the acceleration. 1 or 2 times, the car just dropped to idle and pressing the gas pedal did nothing. I have been told it may be something with the electronic throttle control. once the car actually shut off. I was cruising down a long driveway. I tried to restrt several times and it would only run for a sec or two. I then put it in neutral and revved it up when I started it. it revved up and dropped down to idle. I then put it in gear and fine ever since. I noticed once or twice it also wouldnt accelerate at high speed. Goin 60 I tried to accelerate and the rpms climned up, but no accel.

 

I am assuming you have an 850 so you don't have an electronic throttle system.But sounds kinda like the transmission is slipping.Do you have any check engine light or trans arrow flashing?

 

no trans light. What about the fuel filter?

 

I forgot to add that it doesn't seem to me that it would be the trannie with the loss of power and the throttle not reacting with it remaining at idle. i do agree that it sounds liek tranny with the revs and no pull.

 

You said in your last post the rpm's would go up but the car would not accelerate.That is why I say the trans might be slipping.

 

I agree, but i think there are two seperate problems. Sometimes the car will be driving and will just drop to idle and when I step on the gas nothing happens. And the pulse I referred to is the same thing only very fast and repeated. When I have the other problem with no available power, i step on the gas and it reacts with higher revs, but know increase in acceleration. Does it sound like they are both caused by the trans.

 

The no throttle response might be a bad mass flow sensor or fuel pressure dropping after the pump gets hot.The trans slipping is another problem.

 

Ive had to replace the air flow sensor before, but how do I fix the fuel pressure drop if that is the problem? Will these problems show up in code if I hoked up a diagnostic check?

 

The fuel pressure will not show up with a code.Sometimes the mass flow sensor will.If you have a fuel pressure guage hook it up and try to set it by the bottom of the windsheild.drive the car like normal and when the problem comes up look at the guage and if the fuel pressure is not where it is supposed to be it will need a new fuel pump.

 

Makes sense...... I just went to the grocery store and my check engine light and service light were on, but my abs and trac light were not. As I started drivin, I felt the abs kick in and make a noise then the lights came on. After goin about a mile or two, the service light went off, but check engine was still on. It looks like a Christmas tree in my gauge cluster.

 

Now you still have 2 diffrent problems.The check engine light.The ABS light which is probably a bad ABS module.The check engine light you have to pull the codes to see what is wrong.The service light is just an oil change reminder.If your car is 95 or newer you will have to find a scanner to pull codes.

http://home.earthlink.net/~vicrocha/...vo_V70_ABS.htm
follow link for ABS module rebuild company.

I just noticed in another post your car is a 1994 follow this link for engine codes and how to pull codes.

http://www.troublecodes.net/Volvo/

 

The problem ended up being a bad o2 sensor and knock sensor. steering was bad tires, bad tire rods, and bad stabilizer end link.Not too bad. Easy 1 day project

 

Glad to hear you got it fixed.