Trying to diagnose what might be wrong with a significant hesitation with quick acceleration. Car is put away for winter storage and will soon be replacing factory injectors with Bosch III's from Southbay. Below are the items that I've already had replaced.


IAC (Standard Motor Products AC1T)

ICM (GM Genuine Parts D1943A)

Ignition Coil (Delphi GN10048)

CTS (ACDelco Professional 15-51107)

PCV Valves (ACDelco CV774C)

Fuel Pressure regulator Diaphragm (Standard Motor Products PR10)

Air Filters (Spectre HPR3915)

Fuel Filter (Purolator F33144)


Nothing triggers the SES light, but it has a rough idle and smells very rich.


Any help or previous experiences would be greatly appreciated.

 

I'd start with the basics, verify fuel pressure and get a datalog. I'm suspicious of vacuum leaks, maf, and injectors in no particular order.

 

I found a vacuum leak on the drivers side PCV hose to the intake and replaced it. Did another vacuum test with starting fluid and no longer have a leak but the engine still bogs when giving throttle. Took a fuel pressure reading at 35psi and 45psi at WOT with the vacuum hose removed from the pressure regulator. After shutting off the car the pressure originally held but dropped to 15psi in 30 minutes. I have another video of what it sounds like with a noise coming from near the air cleaner box when giving throttle.

 

Removed the CTS to keep in open loop and did not get the same hesitation. Tried the Actron CP9690 scanner but would not communicate with the ECM. Replaced the ECM and the scanner now works and the cars runs fine again.