Fuel or ignition?
Thread Starter
Race Director
Joined: Jul 2000
Posts: 16,499
Likes: 2,384
From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
2022 Corvette of the Year Finalist -- Modified
2021 C6 of the Year Winner - Modified
2020 C7 of the Year Finalist -- Modified
2020 C6 of the Year Finalist - Modified
Fuel or ignition?
98 convertible stock LS1 with 135xxx miles. After a long drive and then shut down for 30 minutes or more, the car starts fine and idles fine. Once in gear and attempting to accelerate, it will bog down to near stall. Can put it in neutral and blip the throttle a few times and all goes back to normal and will stay normal for return home. Can let it sit and it will start back up with no issues. This has happened twice. The second time was after a 113 mile trip and after refueling. The fuel pressure is a steady 58PSI at idle and with throttle open. There are no codes. All of the plugs look even with no fouling and all of the plug wires ohm out ok. The fuel filter was replaced at the dealer last year after the shift cable was replaced.
I had a similar issue with an 89 with a TPI L98 and it ended up being a fuel pressure regulator.
I'm stumped on this one as neither I or the tech at the dealer can get it to duplicate or find an issue. Is it possible there could be crud in the tanks or lines? Would something in the ignition system cause this? It clears up when the throttle is blipped a few times. Should I just let it stall completely the next time and see if codes are thrown? Thanks for any and all help.
I had a similar issue with an 89 with a TPI L98 and it ended up being a fuel pressure regulator.
I'm stumped on this one as neither I or the tech at the dealer can get it to duplicate or find an issue. Is it possible there could be crud in the tanks or lines? Would something in the ignition system cause this? It clears up when the throttle is blipped a few times. Should I just let it stall completely the next time and see if codes are thrown? Thanks for any and all help.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,552
Likes: 4,025
From: Cape Coral, Florida
HAPPY LABOR DAY !!
This issue of yours can be a few things but without some pinpoint diagnostics you’ll probably just be firing the parts cannon...had ANY recent maintenance been performed prior to your issues ??...any current codes ??...do you maybe have a scan tool so we can maybe look at some data PIDS to get some direction ??...yes, it can be fuel delivery, TPS, ignition...have you checked the coil ??...you can try disconnecting the MAF sensor first and take it for a ride and stomp on it again and see if it bogs down ...your CEL light will come on but we know why it did...having a scan tool and looking at fuel trims and some MAF data would be golden !!...looking at fuel trim data we can see if it’s possibly MAF related or fuel delivery related depending on what we see with the fuel trims !!...with your DVOM I can probably help with some of the diagnosis if you like !!...good luck !!
This issue of yours can be a few things but without some pinpoint diagnostics you’ll probably just be firing the parts cannon...had ANY recent maintenance been performed prior to your issues ??...any current codes ??...do you maybe have a scan tool so we can maybe look at some data PIDS to get some direction ??...yes, it can be fuel delivery, TPS, ignition...have you checked the coil ??...you can try disconnecting the MAF sensor first and take it for a ride and stomp on it again and see if it bogs down ...your CEL light will come on but we know why it did...having a scan tool and looking at fuel trims and some MAF data would be golden !!...looking at fuel trim data we can see if it’s possibly MAF related or fuel delivery related depending on what we see with the fuel trims !!...with your DVOM I can probably help with some of the diagnosis if you like !!...good luck !!
Last edited by C5 Diag; Sep 3, 2018 at 07:38 PM.
