2009 Aveo, oddity runs at 0 RPM at idle not dying???

[grizz13]

Hi there,
I recently bought an 09 Aveo from a guy that had put a new head on, they guy claimed to know what he was doing and claimed he "checked the timing 4 times." He worked on trying to get it running randomly over a 3 year period, unable to get anything going correctly. When he ran the car when I went to look at it I immediately knew the timing was off. When diagnosing this is what I found: Timing on exhaust cam was advanced, guy used old timing stuff to save a few bucks, throttle body needed replaced (ACDelco), gas pedal with sensor replaced (ACDelco), valve cover replaced due to bad PCV, both VVT solenoids were clogged and replaced (ACDelco), both needed new wiring harnesses, cleaned fuel injectors and replaced the O-rings, and replaced intake tubing before and after the MAF, due to cracked tubing causing false air intake. Currently the car runs, at idle below 0 RPM?!?! Hit the throttle stays below 2500 RPM at WOT, as in limp mode, no power, per the code being set. Only code set is the P2122, checked voltage on accelerator harness, all pins reading voltages at 3 pins read at 4.75ish and 3 other pins reading .08ish volts. I know one pin is supposed to be .17-.19 volts, but I don't know which one. The car runs ok at idle after playing with the throttle as it acts like starvation is happening randomly, then after running for 30 seconds at idle it runs fine, but shows under 0 RPM on the dash the car does not want to quit except when having the hiccups. I think I am correct that the wiring needs fixing between the accelerator pedal to the ECM, but I am lost on the problem with the 0 RPM problem?!?!

[grizz13]

Battery and alternator check out ok, until the hiccups as the alternator is hesitating too. Alternator runs at 14.15volts, when hiccups happens the alternator drops the output.

[Eg.h2o]

I’d start with looking at the TPS sensor, also check the wiring and pin fitment. A failure in that circuit will give you the symptoms you have.

[grizz13]

I’d start with looking at the TPS sensor, also check the wiring and pin fitment. A failure in that circuit will give you the symptoms you have.

The TPS is new. I did try to do the relearn, but the code is set so maybe I can't do the relearn? I try clearing the codes by my scan tool 20x, tried pulling ECM fuse and disconnect battery way, and also did the disconnect the battery and connected the pos and neg cables to clear the code. No luck to get it to cleared.

Any who, I decided to run some more tests after searching more on random tech stuff on this forum, the conclusion I have come to is the fuel pump sock is clogged and the pump isn't providing enough fuel causing the hiccups. I banged on the top of the pump with a mallet a couple of times, and the car now can hit 3500 RPMs, but now won't idle even with fresh gas in it. So now I have that one solved. Back to the pedal, which since I disconnected it at the upper harness under the dash instead of at the pedal I now get a better response to revving the engine, not near as delayed and as I said now get up to 3500 RPMs. Oh, and the idle (when it could), was at about 500ish RPMs so maybe a fluke with the fuel starvation? I am totally entertained with this one at the moment...

[grizz13]

Oh and the P2122 was set before I did any work on the car, I decided to replace the accelerator pedal and sensor early on, then the code was still there, so I put a new throttle body on it. With no change on how the car had run.

[grizz13]

Oh, I guess it doesn't have a sock at the pump. EDIT: interesting, no parts stores or online shows that it even has a fuel filter??? HOW?!?!?! This is so stupid...

[Eg.h2o]

Well….at least the fuel pump is easy to change. Just pop out the bottom of the back seat.

i still think you need to perform the idle relearn again, or have a shop do it with their shop tools.