: 01 STS - Engine cutting out on accel

05-25-09, 09:37 AM
My 2001 STS Northstar is seriously cutting out on acceleration.

The engine cuts...if you let off on the pedal it runs smooth. If you hold down on the gas pedal it bucks...hard. Like the engine is completely shutting down for a split second and then back running.

No codes or dash lights are coming on.

It is at my mechanics now and he has a couple of hours into it and still does not know what is wrong.

Any known issues with similar symtoms?

I did relace the Crankshaft position sensors a couple of years ago. But that shut the engine completely down. Plus tripped codes.

05-25-09, 10:18 AM
Fuel pump maybe? Sounds like its definetely fuel related. How are your injectors running?

05-25-09, 11:20 AM
Yeah, I'd start by checking the fuel pressure. If that turns out OK, then I'd suspect ignition cassette(s) maybe.

05-25-09, 11:57 AM
He said he already checked the fuel pump pressure and that was good. Obviously it is something without a sensor. I will talk to him tomorrow and suggest the ignition cassettes. I will be honest... I have no idea what that even is.

05-25-09, 01:10 PM
Motor mount?

05-25-09, 01:30 PM
I had a car with a similar problem , the cause was when you steped on the gas the eng tourqed and pulled a groung wire that was broken inside the covering when you let off the gas the wire reconnected and ran ok, no codes were set as the computer was thinking the batt was being disconected and cleared them evertime this happened...Just thinking..I would go around and pull on every ground and see if this is not the case, you'll know when you find one..

05-25-09, 05:08 PM
I missed that the fuel pressure was tested. Pre 2000 Northstars had 4 coils mounted on the ICM (Ignition Control Module) with wires running from the coils to the plugs. If you look at your engine you will notice the lack of ignition wires. In 2000 GM went to COP (Coil On Plug) ignition. Look at the cam covers. See the insert in it? That is what is called the cassette. It is your coils & ICM.

05-26-09, 10:24 AM
Just heard back from the mechanic.

Two problems.

Front motor mount is broken. He said it is the mass air flow sensor that was cutting the engine. I am surprised that did not trip the code. He is going to do the motor mount first and see what happens.

05-26-09, 11:33 AM
Hmm, I didn't think a bad MAF sensor would take that kind of a toll.