98 S70 t5 missing after replacing cps., P0300 etc

[jblackburn]

A bad mass airflow sensor can do weird things.

We had one on our Buick that would run like crap under 1/2 throttle, but was fine above that. The low RPM stumbling may very well still have to do with that.

[BRONCMAN]

Still havent made it back to check the codes again. Earlier today I drove it about 8 miles & when I went to leave it wouldn't start. It would act like it would try to run, & then just stall as it did the one time before. It was acting like it wasnt getting fuel so I cycles the key a couple times & cranked it & floored the accelerator & it fired up & seemed to run fine & only cut out a couple times on the way home. Also now I can't get it to cut out in park anymore around 1800rpm. Could this possibly be a fuel pressure regulator issue??

Also when i scan it & it has any MAF codes i will replace it. Just beginning to think this could be a fueling issue.

[steve850]

My 840 did exactly that, was a vacuum line off the air intake next to the airbox.

[erikv11]

Unplug the mass airflow sensor (engine off) and see if it runs any better.

I know this was suggested over a week ago, but what happened when you tried this, do you remember?

[BRONCMAN]

Runs fine with the MAF sensor unplugged. Just reduced power. Looks like I need a new one. I'm actually surprised it runs as well as it does without the MAF plugged in. Just drove it 550 miles today.

[erikv11]

It runs fine without a MAF because the ECU is running the default air:fuel mixture. I wouldn't run 500 mile days without a MAF, you are guaranteed the car is either running rich (not so bad) or lean (potentially very bad) all the time. Not a good solution for long-term.

Get a Bosch or Volvo MAF, don't waste your time with any other brand.