Konstantine16

I ordered a ECU off ebay that was matched to my VIN for a 2000 trans am and then took it to a tuner who supposedly put a tune for my cam and 42 pound injectors directly on the computer while it was still out of the car. I then had the computer ECU installed on my car and hell broke loose. The car started but blows black smoke when you give it gas and blows white smoke when idiling and constantly tries to stall out and die. Tried putting original computer back in but now the car runs very rough and only starts when you give it gas and still blows white smoke when trying to die. PLEASE HELP I have no idea why its doing this

LS6427

iTrader: (2)

First.....check all connections. Check the PCM to engine ground also. Black smoke is PIG rich, which means the tune is WAY WAY off.

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wssix99

iTrader: (5)

Talk to your tuner and see what they did. I wonder if you have to take the car for a drive so it can go through the "learn" procedure and properly set the parameters. Each time you cut power to the ECM, it needs to go through this procedure.

Konstantine16

They think its a short in a wire in the wiring harness some place now. This is gonna suck.

LS6427

iTrader: (2)

Did you check the 4 or 5 ground wires that attach to the back of both heads. 2-3 on the drivers side head and 1 or 2 on the passengers side head. ((depends on year)) Reach back behind them and feel the bolts, make sure they are all tight. When mine came loose my engine barely ran, passengers side wouldn't fire and raw fuel was shooting out the exhaust pipes.

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Konstantine16

My mechanic says he checked those grounds first before anything else but I think I'm gonna just grab a flashlight and feel around in there with my own hands to make sure at this point. getting pretty desperate to get this thing running properly

LS6427

iTrader: (2)

You should also check the 3 grounds in the wiring harness leaving the PCM. You can get the exact location of the 3 grounds from the dealership, or maybe someone here can provide them.

There's 3 ground connections in the wire bundle within 10 inches of the PCM......

Also....start the engine and grab those wire bundles and move them back and forth, side to side......see if the engine runs better at times. Thats a tell tale sign its something in the wiring harness.

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keliente

iTrader: (22)

Did you install the cam & injectors at the same time as you bought the PCM and have it tuned?

keliente

iTrader: (22)

Disconnecting the PCM/battery can cause a funny idle but there is no relearn that would fix black or white smoke. That is either a tune problem or a mechanical problem.

Konstantine16

I think it is a loose ground or some kind of wire because the problem comes and goes randomly. My friend told me his school has a diagnostic program that locates loose disconnected grounds and says where they are. Seems like dealerships would have this diagnostic system also. Should I try and take the car and have this done?