Live Data TPS % Stuck at 86% - No Start

Hello fellow Aveo enthusiasts,

I have a 2005 Aveo ls hatch auto, 158k, all new timing components, new exhaust and intake valves, new head gasket, new oil pressure switch, new crank sensor, new cam sensor. Brand New Battery, holding good charge.

Bought car not running with broken belt and bent valves.

Performed repair. Started car several times. Car ran great. Idled very nicely had plenty of power. no overheat and no codes, no blow by.

Suddenly after parking car overnight the car would not restart the next morning.

Checked live data with OBD reader. Appears Relative and absolute TPS values are very high, 86 and 91%. Everything else appears to be ok. Fuel pressure sits at 52psi with key on. Recall nearly 60 when the car ran. Good fuses all around, no chewed up wiring harness. Have tried unhooking the battery for several hours at a time (as to "reset" ecu) with same results.

I've checked the voltage at the TPS. Appears to gradually move from .5v to 4.5v as expected. Unplugging TPS does not change values shown on OBD reader. The values don't change at all actually TPS plugged in or not. Throttle blade at any position the values do not move on the reader.

I believe the car is in a clear flood mode. I do not hear clicking at injectors. Spraying just a tag of starting fluid in throttle body will start the car.

I've been pondering this for about a week, and multiple times now it has had this issue for a day or two, then randomly started once or twice, then back to this again. When it runs it runs good.

Any assistance will be greatly appreciated! Thanks in advance!

BigRigButters

a shot in the dark, but check the oil pressure switch on the back of the timing cover area, oil pump. If it is unplugged, clogged, or anything, it cuts fuel iirc.

Not sure about the 86% on the TPS. The you sprayed starting fluid in it, was the throttle body stuck open? Very often the aveo throttle bodies need cleaned (or replaced).

Quote:

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Originally Posted by BigRigButters

... The values don't change at all actually TPS plugged in or not. ....

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If I'm understanding correctly, you're saying that the OBD reader relative throttle position remains high, even if the TPS sensor connector is unplugged? If so, that's a really helpful and revealing piece of diagnostic information! Disconnecting the TPS sensor connector should result in an OBD reading of close to zero relative throttle position, and also set a P0122 (signal too low) DTC.

So, if the value remains high with the connector unplugged, it must mean either a sporadically shorting signal wire, or (less likely) a problem with the ECM. Is the white signal wire (C) pin at the connector showing 4+V? If so, the short is probably right there in the connector. But if that wire at the connector is showing 0V, then check the continuity of that wire (to ECM connector pin #6). If there's no continuity, then there must be a short of the signal wire to reference (or some other power source)

But if there is continuity between those wire end points, it would then appear to be an ECM issue. But before replacing the ECM, I'd try to get a jumper wire into ECM pin #6, just to confirm that it really does read 0V at that point. My guess would be a short somewhere.

Thank you both for your input,

Sorry for the delay in response time, I know its been a while but it was in fact a short in the signal wire. Thanks to your help I was able to get it sorted out and ran a new wire and it started and ran great every time!

Shout out to avguy!! appreciate it!! Enjoy your Aveos all!!