adj. TPS lost power

[dpmeeks]

My idle was acting kinda funky so i decided to reset my TPS and base idle. It idles perfect now, but, i noticed it seemed like i lost boost pressure. I checked my stock gauge and it was about 11psi which was a lil less than i had it set ( i have a MBC ), so i turned it up to about 15lbs and it feels like its boosting just not going anywhere.

Prior to the above change the car would pull hard all the way ( shouldnt have messed with it )

If i go into it slowly it pulls good, if im in second gear for example and mash on it, when i hit 15lbs it seems like it just stands still a that point .

[svobud]

That doesnt make sense. You make adjustments to an electrical item (the TPS) which is now properly set and a mechanical device (the manual boost valve) starts producing less actuation of the waste gate? So, you have to readjust your boost setting .. and now you feel you're down on power?

Just a thought, you might want to check your timing. It might be a bit retarded.

[Alex L]

Just a thought, you might want to check your timing. It might be a bit retarded.

didja plug the spout back in once you reset the base timing and confirmed it advanced properly?

[dpmeeks]

i know it doesnt make sense.. thats what happened though..

I had another vam laying around and hooked it up same issue, unplugged my knock sensor, still same isssue.

I checked the fuel pressure, ( i did install a new fuel filter yesterday ) at idle its 32psi, unplugged the fpr- 42 psi, and at 15psi boost its about 52psi so i dont think its a fuel issue..

I havent messed with the timing at all, Im thinking its my TFI or timing is off, occassionally i get a small back fire or hiccup and it acts like it wants to cut out at low rpms ( sometimes ).

Like you said bud, i think its a timing issue, its hard to explain but the engine revs up great, boost is there, just seems like the power is gone..

[NavySVO]

I checked the fuel pressure, ( i did install a new fuel filter yesterday ) at idle its 32psi, unplugged the fpr- 42 psi, and at 15psi boost its about 52psi so i dont think its a fuel issue..

The rule of thumb is 1 psi fuel for every pound of boost. 42 + 15 pounds of boost does not = 52.

[dpmeeks]

yeah its a lil short i guess.. but, it was boosting fine yesterday and im fairly confident the fuel press. was the same.

[svobud]

dpmeeks .. what Kurt might be suggesting; it might be lean, which causes detonation - and IF the knock sensor is still hooked up, it will pull power down (timing) to counter the possible engine damage from the detonation. It's a thought.

[dpmeeks]

I tried it with the knock sensor unhooked and still no change.

[dpmeeks]

I checked the timing its 10deg spout out and 24deg spout connected

[dpmeeks]

I installed a new fuel filter yesterday, if I installed the filter backwards could that cause the problem with the above fuel pressure readings

[BrianO]

easy enough to check.. crawl under and find the arrow...

if backwards it won't filter as well and will plug up faster.

[dpmeeks]

yeah but i dont think its gonna cause my loss of power issue, since my FP is in good shape

[dpmeeks]

the fuel filter is installed correctly.. i decided to go back where i started and mess with the TPS. I can adjust it one way and when i mash on it the hesitation gets worst. If i adjust it the other way and mash on it, i get a very slight hesitation. If i accelerate slowly no hesitation at all and pulls hard like it use to.

bud, if i read correctly the TPS is what tells the eec how much fuel to add as the throttle plate opens, so, if its a bad TPS then i could be running lean and causing the loss of power and hesitation. What makes me think its the TPS i can accelerate slowly and it doesnt do it. The fuel pressure stays steady when i mash it so i dont think its a fuel problem. I checked over the ignition system today and everything looks good.

[svobud]

Yeah, the TPS sends a signal of how far the Throttle Body butterfly plate is open/closed. Have you checked/tested the VAM? Do a search for VAM test or VAM Test Procedure. It's a thought.

[dpmeeks]

i have a spare vam and tried it with no luck