84 misfire issues
Thread Starter
Heel & Toe
Joined: Jun 2012
Posts: 22
Likes: 0
84 misfire issues
Hey all. Have a 84 corvette with crossfire injection still. Just recently completed some internal upgrades in the motor and tracing down a strange misfire.
List of mods:
1. renegade performance intake
2. comp xe249 Cam
3. comp lifters
4. summit valve springs, pushrods, retainers, and keepers
5. new fuel pump, new knock sensor, new map sensor
6. roller tip rocker arms
Timing is set at 6 degrees btdc
Ive put about 600 miles on the set up and been trying to track down the misfire it has. I have no cel on. It runs very rich and smells of it. In the morning cold it will have a rough idle until it warms up. Some really cold days it wont idle by itself without feathering the gas for a minute or two. Runs fine at idle once warm and starts easily. Runs great at wide open throttle and takes off. Just daily typical driving cruising down the road is when i get my misfire. it can range from light to extreme. Taking off from a light about half throttle yields a definite skip and shake. Other times you will be driving 50mph and running great and all of a sudden it will backfire through the throttle boys and out the exhaust like a machine gun, let up on the gas and ease back into it and its good to go. Any thoughts on what i have going on? The problem is very intermittent and driving me nuts. My fuel mileage is terrible and the car is definetly running rich. Cam was broken in correctly and by watching all the springs all seems well there. Thanks for any suggestions you guys might have!
List of mods:
1. renegade performance intake
2. comp xe249 Cam
3. comp lifters
4. summit valve springs, pushrods, retainers, and keepers
5. new fuel pump, new knock sensor, new map sensor
6. roller tip rocker arms
Timing is set at 6 degrees btdc
Ive put about 600 miles on the set up and been trying to track down the misfire it has. I have no cel on. It runs very rich and smells of it. In the morning cold it will have a rough idle until it warms up. Some really cold days it wont idle by itself without feathering the gas for a minute or two. Runs fine at idle once warm and starts easily. Runs great at wide open throttle and takes off. Just daily typical driving cruising down the road is when i get my misfire. it can range from light to extreme. Taking off from a light about half throttle yields a definite skip and shake. Other times you will be driving 50mph and running great and all of a sudden it will backfire through the throttle boys and out the exhaust like a machine gun, let up on the gas and ease back into it and its good to go. Any thoughts on what i have going on? The problem is very intermittent and driving me nuts. My fuel mileage is terrible and the car is definetly running rich. Cam was broken in correctly and by watching all the springs all seems well there. Thanks for any suggestions you guys might have!
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Is the cam you installed close to stock? If not, you should probably have a new chip burned. Sounds like your getting too much fuel and it is build up (unburned) until it is ignited and backfires.
Next I would double check the valve to be sure that they are set correctly. One valve a little too tight would allow the burning fuel to escape up thru the intake and backfire other fuel to the cylinders.
Check the plugs next to see if they are fouling. Then I would OHM the wires to be sure that they are good.
Next I would double check the valve to be sure that they are set correctly. One valve a little too tight would allow the burning fuel to escape up thru the intake and backfire other fuel to the cylinders.
Check the plugs next to see if they are fouling. Then I would OHM the wires to be sure that they are good.
