Misfire
Thread Starter
Heel & Toe
Joined: Mar 2015
Posts: 23
Likes: 1
From: Dubai
Misfire
Ok so i'm new to the forum and new to corvette's in fact new to american cars full stop (or 'period' as you crazy yanks say).
I got my 1991 L98 a couple of days ago and its awesome, don't know why I wasted so much time with 4 cylinder FWD European cars!
However I have a misfire problem, I have searched the forum and read various posts but i'm hoping to get more of a specific answer/most likely cause.
The cars runs great with plenty of power when cold but 5-10 minutes of driving and it starts to warm up, that's when the misfire starts! I'm guessing its when it changes from open to closed loop? Due to the fact that it runs great when cold i'm thinking its more of a sensor problem than plugs/leads/injectors etc
Any ideas of what to check first? any common sensor faults? Hoping you guys can save me some time and $$
Thanks in advance
I got my 1991 L98 a couple of days ago and its awesome, don't know why I wasted so much time with 4 cylinder FWD European cars!
However I have a misfire problem, I have searched the forum and read various posts but i'm hoping to get more of a specific answer/most likely cause.
The cars runs great with plenty of power when cold but 5-10 minutes of driving and it starts to warm up, that's when the misfire starts! I'm guessing its when it changes from open to closed loop? Due to the fact that it runs great when cold i'm thinking its more of a sensor problem than plugs/leads/injectors etc
Any ideas of what to check first? any common sensor faults? Hoping you guys can save me some time and $$
Thanks in advance
Melting Slicks
Joined: May 2014
Posts: 2,888
Likes: 590
From: New Port Richey FL
Ok so i'm new to the forum and new to corvette's in fact new to american cars full stop (or 'period' as you crazy yanks say).
I got my 1991 L98 a couple of days ago and its awesome, don't know why I wasted so much time with 4 cylinder FWD European cars!
However I have a misfire problem, I have searched the forum and read various posts but i'm hoping to get more of a specific answer/most likely cause.
The cars runs great with plenty of power when cold but 5-10 minutes of driving and it starts to warm up, that's when the misfire starts! I'm guessing its when it changes from open to closed loop? Due to the fact that it runs great when cold i'm thinking its more of a sensor problem than plugs/leads/injectors etc
Any ideas of what to check first? any common sensor faults? Hoping you guys can save me some time and $$
Thanks in advance
I got my 1991 L98 a couple of days ago and its awesome, don't know why I wasted so much time with 4 cylinder FWD European cars!
However I have a misfire problem, I have searched the forum and read various posts but i'm hoping to get more of a specific answer/most likely cause.
The cars runs great with plenty of power when cold but 5-10 minutes of driving and it starts to warm up, that's when the misfire starts! I'm guessing its when it changes from open to closed loop? Due to the fact that it runs great when cold i'm thinking its more of a sensor problem than plugs/leads/injectors etc
Any ideas of what to check first? any common sensor faults? Hoping you guys can save me some time and $$
Thanks in advance
I have found in the past that as engine temps go up that a weak plug wire will show, take a digital volt meter do a resistance/continuity test on each wire they all should be plus or minus the same with longer ones being a bit more. if 1 or 2 is super high or open that may be your problem. also look for signs of arcing.
Last edited by s carter; Mar 12, 2015 at 12:35 PM.
Burning Brakes
Joined: Apr 2012
Posts: 888
Likes: 4
From: Ridgecrest Ca
It also wouldn't hurt to perform a resistance check/voltage check of the coil both hot and cold as well. But the plug wire check is most important as s carter stated. Also consider checking for vacuum leaks around the intake plenum too when hot. Sometimes things open up a bit when hot but in open loop is compensated for. Check the distributor cap for cracks as well.
Safety Car
Joined: Aug 2009
Posts: 3,745
Likes: 275
From: Melbourne, Victoria, Australia
Hi
Check the ignition leads, coil and make sure the injector harness is connected securely to the injectors.
Spark plugs are the usual culprit, high mileage engines tend to foul the plugs. Heat is another killer, replace the spark plugs.
Have you checked the EGR valve is not sticking open? that will cause rough idle and stalling.
Good luck
Check the ignition leads, coil and make sure the injector harness is connected securely to the injectors.
Spark plugs are the usual culprit, high mileage engines tend to foul the plugs. Heat is another killer, replace the spark plugs.
Have you checked the EGR valve is not sticking open? that will cause rough idle and stalling.
Good luck
