I post this in another forum, I guess I can get better help here....
It all started couple of days b4 intake swap (Edelbrock intake, Aarons elbow, Wilson TB, etc)
SES came on and I scanned it with my android. Infamous P0200- Injector Circuit. The truck had a rough idle and misfired when driven. I erased the code with my android and things went back to normal…so I thought.
The day I was letting it in the shop for the intake swap it started again, this time with heavy fuel smell. We trace the fuel leak to the #8 piston….it was flooding that chamber with fuel. We disconnected that injector and idle was better and engine resume some “normal behavior”.
My first thought, Injector damage. So I took all the injectors out and send them to test and clean. Injectors where perfect. So I installed them again but this time I changed position to the one that was in #8 piston.
Turn the truck on and same issue. Injector #8 stayed wide open.
I consulted some known Gurus around here and told me my ECM injector driver was doom. So I have to replace the ECM.
Well, that sound easy, but I will have to spend $200 in HP tuner credits. I refuse that yet. I start looking for ECMs to test in my truck. All locked or wrong year. So I took another approach. I got mine reflashed and tested in a friend’s 2002 Tahoe.
It worked perfect for the 3 days test. So At this point I ruled out my ECM as the problem !
Those 3 day testing gave me time to swap intake. So the swap is done. I took my ECM, write entire again with my tune. And VOILA!!! It idle perfect. No roughness. No code, no nothing. So I start tuning my idle.
Went for a spin to test the truck and a few blocks away from the shop SES came on…monstrous P0200 attack again. Rough truck behavior now. Try to erase it with HPtuners and came back on in a minute. Took the truck to the shop and let it there sit for a while. Try to start it again and almost hydrolock. I called a day.
Now I know for a fact that when my ignition is on, the #8 injector work like all others. They all pressurize and turn off until cranking. Once the truck is running #8 stays wide open!!!
Now I hit the wall and don’t know what to do.
So guys, If you have any other test procedure, any other part I should look at, fuses, wiring (wiring was check 50% and rerouted because of intake swap), etc, let me know.