Help/Ideas Needed - 1993 Z28 - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

CM-NY · 07-27-2015, 07:28 PM

Hello. So I'm posting here hoping someone might have a clue because my mechanic (who has kept my car running wonderfully for 5 years so far) is running out of ideas. Here's the scenario.

Start it up and everything seems fine. At some point when I'm driving it, typically between 2-6 miles which depends on how hot the weather is (hotter = sooner), it will begin to have problems. Sometimes it will stall out of the blue. Sometimes when that happens, the engine will restart after a moment (instantly or even 5 seconds later). Other times it doesn't restart at all. Even when it restarts once or twice it will eventually just stay stalled out and I need to get over onto the median/shoulder. There will then be a period of 5-10 minutes where the engine won't catch at all or it will stall out again either immediately or if I rev the engine a little. Stalling is more likely the hotter it is.

Other times, instead of stalling, the RPMs appear to not increase if I'm accelerating. This happens between 1000-1500 RPMs. They will then wobble and sputter as if the car is suddenly accelerating then dropping back. It's almost guaranteed that the car will stall if I don't ease up on the accelerator and take it down to 1000 RPMs. This can continue for a few miles.

Then the most puzzling thing happens. The problems stop and it drives fine again. My commute is only 9 miles so I don't know if the problems would start again while I'm driving it but they do reoccur on the drive back. Needless to say, this makes diagnosing things difficult. The distributor and wires have been replaced, the ground wires checked, the alternator is fine. They're very competent so I'm going to assume the obvious problems have been checked.

So, has anyone ever had this happen to them or heard of such a thing? I'll try to answer questions as I can but I'm not a mechanic and don't tinker. Thanks in advance.

VTSummit · 07-27-2015, 07:31 PM

It's your fuel delivery. Have him put an in-line gauge on the fuel line and drive it.

MrChrisLS3 · 07-27-2015, 11:30 PM

The LT1 engine. You said that that the distributor was replaced. One of the other parts of the ignition system that could cause this is the ignition control module. It is located on the passenger side head. Over time, the heat sink grease on the back can wear out, causing the ICM to over heat and fail. It can be easily checked by taking it to the auto parts store and they can check it for you. Easily removed with a 7mm socket.

The fuel pressure regulator is another common culprit here. Simple check, just remove the vacuum line and look for fuel. If it's wet, it's bad.

You will probably get some more attention over in the 4th gen section, however.

CM-NY · 07-27-2015, 11:38 PM

Thanks for the suggestions. I'll mention the fuel delivery to my mechanic. Also the pressure regulator. We already tested the control module and it's fine. I'll post this in the other section then too.

07-27-2015, 07:28 PM	#1
CM-NY Drives: 1993 Z28 Join Date: Jul 2015 Location: NY Posts: 4	Help/Ideas Needed - 1993 Z28 Hello. So I'm posting here hoping someone might have a clue because my mechanic (who has kept my car running wonderfully for 5 years so far) is running out of ideas. Here's the scenario. Start it up and everything seems fine. At some point when I'm driving it, typically between 2-6 miles which depends on how hot the weather is (hotter = sooner), it will begin to have problems. Sometimes it will stall out of the blue. Sometimes when that happens, the engine will restart after a moment (instantly or even 5 seconds later). Other times it doesn't restart at all. Even when it restarts once or twice it will eventually just stay stalled out and I need to get over onto the median/shoulder. There will then be a period of 5-10 minutes where the engine won't catch at all or it will stall out again either immediately or if I rev the engine a little. Stalling is more likely the hotter it is. Other times, instead of stalling, the RPMs appear to not increase if I'm accelerating. This happens between 1000-1500 RPMs. They will then wobble and sputter as if the car is suddenly accelerating then dropping back. It's almost guaranteed that the car will stall if I don't ease up on the accelerator and take it down to 1000 RPMs. This can continue for a few miles. Then the most puzzling thing happens. The problems stop and it drives fine again. My commute is only 9 miles so I don't know if the problems would start again while I'm driving it but they do reoccur on the drive back. Needless to say, this makes diagnosing things difficult. The distributor and wires have been replaced, the ground wires checked, the alternator is fine. They're very competent so I'm going to assume the obvious problems have been checked. So, has anyone ever had this happen to them or heard of such a thing? I'll try to answer questions as I can but I'm not a mechanic and don't tinker. Thanks in advance.

07-27-2015, 07:31 PM	#2
VTSummit Consistently inconsistent Drives: 2015 2LT Summit White Join Date: May 2015 Location: United States Posts: 1,363	It's your fuel delivery. Have him put an in-line gauge on the fuel line and drive it. __________________ Thanks to MRR, I have some SWEET wheels! Thank you! 2015 2LT Ported TB, Ported intake, JACFAB intake spacer, Borla exhaust, IPF 91 tune, Complete 1/LE suspension, Brembo brakes, Goodridge lines, Elite catch can, CAI with Thermo-wrap, 275/40-20 x 10's all around, Z/28 spoiler, GM splitter, Alpine/Polk stereo with AudiControl interface.

07-27-2015, 11:30 PM	#3
MrChrisLS3 Drives: 2018 1SS M6 Join Date: Nov 2014 Location: Houston Posts: 2,617	The LT1 engine. You said that that the distributor was replaced. One of the other parts of the ignition system that could cause this is the ignition control module. It is located on the passenger side head. Over time, the heat sink grease on the back can wear out, causing the ICM to over heat and fail. It can be easily checked by taking it to the auto parts store and they can check it for you. Easily removed with a 7mm socket. The fuel pressure regulator is another common culprit here. Simple check, just remove the vacuum line and look for fuel. If it's wet, it's bad. You will probably get some more attention over in the 4th gen section, however.

07-27-2015, 11:38 PM	#4
CM-NY Drives: 1993 Z28 Join Date: Jul 2015 Location: NY Posts: 4	Thanks for the suggestions. I'll mention the fuel delivery to my mechanic. Also the pressure regulator. We already tested the control module and it's fine. I'll post this in the other section then too.