Power problem!!

[iamdub]

Engine load (measured in part by the MAP sensor) is calculated in determining the injector pulse width/duty cycle. Free-revving in neutral/park is a low-load condition so the amount of additional fuel needed is much smaller than when under load. What about if you sharply stab the throttle in park/neutral after it's been driven and is acting up, does it stutter for a split second before it revs?

Do you have access to a scan tool that can show real time data?

 

[oldsman003]

Unfortunately my scan tool only reads freeze frame at the time of a code. I have always noticed it does not act up in parking regardless the quick stabs of throttle. The flashing check engine light appears more and more often and now will flash most of the time it gets driven.

 

[iamdub]

Sounds like it's getting worse. If it is a lean misfire and you continue to drive it, you could kill your motor.

 

[oldsman003]

I wish it would just throw a code so i know whats going on but its not, and I hate throwing parts at it, money spent that it doesnt need.

 

[iamdub]

^^^ That is another odd element in all of this- that you have no cats but no "Catalyst Inefficiency" codes.

Checking the fuel pressure shouldn't cost you anything but time. A scan tool for live data would probably pinpoint the cause right away.

 

[oldsman003]

Yes I thought that was very odd that no codes were thrown after the cats got opened up. I will hook it up to my scanner tomorrow and see if anything is in there. I hope I can figure this out because the truck runs great otherwise aside from when it wants to fall on its face.

 

[rockola1971]

Unfortunately there isnt a bad fuel pump code but there are some that can point to a bad pump. Lean condition type codes being one of them. I once had an older camaro that would run fine in the driveway but as soon as I got it on the road it ran like it had a partially plugged up fuel filter. Guess what else it did? Flashed the check engine light. This was an early OBDII system.