Running rich, wont boost, misses and bucks like crazy - need a savior

[Tweek711]

My car has been running shitty for a month and a half. There are no mods, it runs ridiculously rich under boost (throws black smoke out), it bucks real hard and wont move under boost, and starts missing (probably due to rich mix). Anyway, Ive had it to several mechanics and 2 dealerships, all not being able to find anything. The one thing I found was when using a scan tool the TPS values were erratic jumping from 8-11 at idle and 80-100 at full throttle. When tested on my friends car they were dead on, not jumping around. Replaced the TPS with 2 different ones and problem persisted. I am at a wall no one can figure this out! I need the DSM gods here to give me advice

 

[bling5tatus]

Is your tps properly grounded?
Have you boost leak tested your car?
What do your plug wires/plugs look like?

Sounds kinda like a bad ground to me though.

 

[Tweek711]

thats what im checking as soon as i get the car back is the TPS ground, my buddy and i thought of it when the mitsu dealer just told me that they wouldnt work on it. its good to hear that idea though so i know its a possibility. I replaced the Coil, plugs, wires. The plugs have carbon build up on them from the rich mix. Yeah the car was boost leak tested, that was my original thought when it first occurred

 

[bling5tatus]

Well good, make sure after you check it and fix it, post back here so we can have that info for future people having the same issue.

You did say that the same tps that was acting all jacked on your car was fine on your friends? Or you just checked the tps that was on your friends and saw that it moved smoothly? If your tps works fine on your friends I would definitely say it's a problem with the wiring harness not being grounded properly. good luck... and let us know what you come up with.

 

[Tweek711]

we checked my friends and it was fine, then my friend grabbed 2 he had from his parts stash and swapped them on my car and they had the same effect. Yeah i get the car back tomorrow and ill make sure to post back up

 

[oldman]

Yeah the car was boost leak tested

Describe in detail the method, process and results of the boost leak test.

 

[Tweek711]

a dealership did it, said they primed the intercooler and piping to a certain psi (cant remember how much) and left it sit while they worked on another car and came back and it hadnt dropped in pressure

 

[bling5tatus]

Correct me if I'm wrong, but should it drop in pressure anyway, like even if the "boost leak" test is good, over a certain period of time the pressure should drop right?

 

[oldman]

a dealership did it, said they primed the intercooler and piping to a certain psi (cant remember how much) and left it sit while they worked on another car and came back and it hadnt dropped in pressure

1. We require our members to use proper grammar, punctuation and capitalization, please comply.

2. Dealers or most shops doesn't know how to perform boost leak tests because it's a PITA job and takes too long, perform your own test and post back results.

 

[Tweek711]

sorry they did say it dropped 1/2 a pound

 

[oldman]

a dealership did it, said they primed the intercooler and piping to a certain psi (cant remember how much) and left it sit while they worked on another car and came back and it hadnt dropped in pressure

sorry they did say it dropped 1/2 a pound

They're lying to you.

 

[Tweek711]

I guess that's a possibility, but I would hope not because it was a friend of mine who worked at the dealer that did the work. Ill do my own and see what the results are

 

[oldman]

I guess that's a possibility, but I would hope not because it was a friend of mine who worked at the dealer that did the work. Ill do my own and see what the results are

It would suck if a friend lied to you but I have done many many .......boost leak tests and the situation he described doesn't exit, unless he only pumped 2 psi into the system.

 

[bling5tatus]

Haha, glad I didn't respond, I was like, who's lying to me.... and yes, .5 of a pound is not much and really sounds like some bs.

Oldman - would a boost leak have anything to do with his wild tps readings?

 

[Tweek711]

It shouldn't cause crazy TPS readings because readings were done with car running and just to the "on" position both times it was the same result. So if the result was the same with no air running through the system it shouldn't interfere in any way

 

[toyotaturbo]

I would check the ecu and the fuel pressure regulator.

 

[scottyp]

I would check the ecu and the fuel pressure regulator.

I definitely have to agree with possibility of an ECU problem, I've heard of more than a few first gen. ecus that have had the internal battery leak onto the circuit board and melt connections. Some of the first signs are erratic idling, bucking and the like, followed shortly by cranking but not starting. I've had it happen to me and a few friends have had it happen to them so it's worth a check. But you have the right start by checking the TPS then work your way back. As far as the FPR, I would check it just as an avenue to investigate.

 

[redeclipse7782]

Also the ground for the tps on 1gs is on the back side of the tb, its not in the tps sensor or harness. Its on the back side of the tb and is connected to the adjuster that adjusts where the tb stops. Its a single wire, make sure its connected, and has a solid connection. If its your friend who did the boost leak test, make your own boost leak tester, costs $5. or so with home depot parts, and bring it to him and have him boost leak test it infront of you up to around 15-20psi. Even on a good pressurized system all of the air is going to leak out in 15-30 seconds, your job is to hear if there is an air leak anywhere from the turbo to the intake manifold, intake manifold included. Also get a boost/vac gauge to see how much boost you are building and what your vac is at idle.

 

[oldman]

ecus that have had the internal battery leak onto the circuit board and melt connections. Some of the first signs are erratic idling, bucking and the like, followed shortly by cranking but not starting. I've had it happen to me and a few friends have had it happen to them so it's worth a check.

No internal batteries in our ECUs, you're talking about capacitors.