I have posted twice about the issue not starting with no responses, so I guess people are as stumped as me. Now the vehicle has several other additional issues. I think the ECM is going bad but wanted to get other opinions. Here are the codes that are now being triggered.

P0607 Control Module Performance
P0336 crankshaft position sensor A circuit range / performance. (sensor has been replaced twice)
P0305 cylinder 5 misfire detected

Symptoms: trouble starting, no spark then all of the sudden it will start after 1 - 20 times of trying to start it. I checked the spark buy checking the spark on the plug. When the plug gets spark, it starts. When it starts, it use to run perfect. But now it has a Lack of power, this symptom this just started. It has to be the misfire of the 5 cylinder.

The dealership could not determine why it won't start. They replace everything except the ECM. They wanted to do that too but I had them hold off because they could not guarantee that would fix the start problem. Now these other issues have surfaced and I think it is the ECM.

What is your opinion?

Thanks for your thoughts.

JB.

 

What exactly they have replaced or tried to replace?

 

They have replaced the following.
(2) crankshaft sensors
Starter
Battery
Key batteries
Ignition switch
Timing belt ( it was time )

 

I'ts good to get signal recording for crankshaft sensor using oscilloscope.
Because such behaviour can be caused by faulty flywheel. Also check the crank sensor mount. + Can be noise because of starter motor.
+ Not proper ground between engine and transmission.
Misfires are detected using crankshaft sensor signal. So that is additional prove that there is some issue.

 

I spoke to a technician and he said it sounds like the ground between the bell housing and the engine.
That since I had the transmission replaced it sounds like they didn't sand the bell housing which will cause a ground fault.

Anyone else ever heard of that happening?

 

i dont think the ground would be the cause. the reason he said that is because when you replace the 5cyl transmissions with an aftermarket transmission, they usually come painted black so thats when you have to sand the area where the ground cable would go. on the 4t65 transmission, the engine does not come painted so there would be no reason to sand it down

 

He thought it was the ground because when I try to crank it the TAC jumps up. He also said the ground could cause the misfire issue. The transmission was re-built so I tend to agree with you on the ground between the engine and tran. I think is is either the ECM or the a fly wheel issue. Tomorrow I am going to check the tightness of the bell housing bolts to the engine. I guess if these came loose over time it could cause these types of problems.

I'm still interested in hearing any other theories.

 

Update. It turned out to be the grounds on the frame under the hood on the driver side. There are 3 grounds there. When I took off the grounds to look at them I noticed that the fender had been painted and the contacts under the bolts had paint on them. After scraping the paint off and reconnecting the grounds the car starts every time. The cylinder misfire was the coil pack.

 

I'm glad for you it wasn't the ECM! Been there, done that + 16 relays @ $23.00 each, total repair on that ran just over $1700.00