98 XC V70 Loss of acceleration

[Pdxgurl1989]

The Volvo is at 150k miles,I have read this may be a failing fuel pump. I have also read that if the fuel pump was failing the car wouldn't be driving. No fuel pressure test has been done as of yet. At first we had an idle issue where the car would stall at idle and die out (Dropping from 900 rpm to 500 rpm then die). It would also do this going about 30 mph. Having foot steady on the gas pedal and accelerating at a regular pace then loosing acceleration completely. The rpms drop from 2,100 to 900 rpms even with your foot still on the gas pedal. The only way to keep it from dying is if you pump on the gas pedal. Which then it seems like engine will 'catch up'. The first thing I replaced was the MAF sensor (aftermarket) the car was reading a p0103. The car still has a loss of acceleration issue when going 35+ mph the engine would want to die out, it seems to loose acceleration while your foot is on the gas.

I did a full tune up, replacing cap, rotors and all new bosch plugs that were properly gapped. The fuel pump relay has been replaced, and the fuel filter has been replaced it was the original 1998. Before doing the fuel filter replacement the car had problems starting - as if there was no gas reaching the engine. Ever since that's been replaced the car will start up no problem, but is still having acceleration issues at moderate and high speeds ( I Cannot take it on the highway because when I got 55+ it doesnt want to accelerate ).

Earlier today driving about 30 mph it was having the same acceleration issues. Where I had to keep pumping on the gas pedal. The check engine light came on and the code was p0103. Any insight ?

[scot850]

It does sound like a fuel pressure issue, but there are a few other things that can cause issues. But my first check would be the fuel pressure. You can check this at the schreader valve on the injector rail. You should get 42psi minimum when running. Once you have done this let us know what the result is and we can go from there.

One question the other guys will ask is what brands did you use for the replacement parts. These Volvos are very particular on what you use. Bosch cap and rotor, Bougicord plug wires, Bosch MAF. Plugs shoulf be gapped to 0.028".

Neil.

[Pdxgurl1989]

Neil thanks for the reply! I still haven't had the pressure tested on the vehicle, for what it's worth I parked the car today and came back to it about 10 minutes later - it wouldn't start. It would crank and rev up but it wouldn't turn over. Luckily I was parked next to a shop and a mechanic took a look at it. He opened the hood and he also tested the fuel release pressure valve (By releasing fuel from the golden tip next to the motor) and said if it was a fuel issue nothing would be coming out. Then he asked if I had any check engine lights that came on. Of course I said it was the MAF sensor and he said that is what needed to be replaced.

With that being said, I tried starting the car with the MAF sensor plugged in and it still wouldn't start. So I though maybe I will just unplug the damn thing. And sure enough it started. I was able to drive it for about ten minutes and the engine felt really rough but it never sputtered or died. How important is this part? Do you have to drive with it plugged in all the time?

The MAF I just replaced was aftermarket so perhaps this is the culprit.

[RussB]

The MAF is extremely important. If you just replaced it perhaps you can return it, and get a proper Bosch MAF?

[Pdxgurl1989]

Unfortunately I bought this from O'Reileys auto parts, I'm sure they would take it back. Had no idea these cars were so freaking piccckkkyyyyy!!!!

Will purchase a Bosch or Volvo and keep you guys updated. Guess I should probably return the after market fuel relay pump as well lol!

[Pdxgurl1989]

Been driving for the last week and a half - NO ISSUES!!! It's insane how much these cars rely on the MAF sensor. My mind is literally blown. Thank you for all of your help and advice!

[RussB]

Good to hear!