Random Misfire After Mac Header Install
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Teching In
Joined: Jun 2003
Posts: 11
Likes: 0
From: Fresno, Ca
Random Misfire After Mac Header Install I just installed Mac Headers and catted y-pipe, and changed spark plugs (Bosh Platinum 4's) and I am getting a code p0300 (random misfire).
When I start the car up it takes about 10-20 second before the service engine light turns on. The misfire is very obvious, the car even backfires. The car runs poorly throughout the rpm range, it is so bad that if I put it in sixth gear the whole car shakes badly. When I accelerate the car stumbles.
I checked to make sure the spark plugs were in tightly and the plug wires were properly attached to the plugs and coil packs. I also checked to make sure the oxygen sensors were all screwed in tightly. I used the Predator and it had a list of 30 error codes, but none of them set off the service engine light. Some of the codes were odd : speed sensor off, engine coolant too cold for close loop, etc.
I am all out of ideas, and I would appreciate any help thanks in advance.
When I start the car up it takes about 10-20 second before the service engine light turns on. The misfire is very obvious, the car even backfires. The car runs poorly throughout the rpm range, it is so bad that if I put it in sixth gear the whole car shakes badly. When I accelerate the car stumbles.
I checked to make sure the spark plugs were in tightly and the plug wires were properly attached to the plugs and coil packs. I also checked to make sure the oxygen sensors were all screwed in tightly. I used the Predator and it had a list of 30 error codes, but none of them set off the service engine light. Some of the codes were odd : speed sensor off, engine coolant too cold for close loop, etc.
I am all out of ideas, and I would appreciate any help thanks in advance.
I don't know anything about your Bosh plugs but if you are able to check the gap do that first. Maybe you could of cracked a plug or something putting your headers on. They can easily break. You probably paid alot for your plugs but alot of people use NGK TR55's and they only cost $2 each. Just recheck everything again. I know it sucks just hang in there. Also did you have any codes before the header install. Good luck. Maybe change plug wires too.
TECH Regular
Joined: Nov 2001
Posts: 450
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From: Texas
misfire
Originally Posted by Braun
I just installed Mac Headers and catted y-pipe, and changed spark plugs (Bosh Platinum 4's) and I am getting a code p0300 (random misfire).
When I start the car up it takes about 10-20 second before the service engine light turns on. The misfire is very obvious, the car even backfires. The car runs poorly throughout the rpm range, it is so bad that if I put it in sixth gear the whole car shakes badly. When I accelerate the car stumbles.
I checked to make sure the spark plugs were in tightly and the plug wires were properly attached to the plugs and coil packs. I also checked to make sure the oxygen sensors were all screwed in tightly. I used the Predator and it had a list of 30 error codes, but none of them set off the service engine light. Some of the codes were odd : speed sensor off, engine coolant too cold for close loop, etc.
I am all out of ideas, and I would appreciate any help thanks in advance.
When I start the car up it takes about 10-20 second before the service engine light turns on. The misfire is very obvious, the car even backfires. The car runs poorly throughout the rpm range, it is so bad that if I put it in sixth gear the whole car shakes badly. When I accelerate the car stumbles.
I checked to make sure the spark plugs were in tightly and the plug wires were properly attached to the plugs and coil packs. I also checked to make sure the oxygen sensors were all screwed in tightly. I used the Predator and it had a list of 30 error codes, but none of them set off the service engine light. Some of the codes were odd : speed sensor off, engine coolant too cold for close loop, etc.
I am all out of ideas, and I would appreciate any help thanks in advance.
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Originally Posted by Braun
Well guys, the verdict is in there was 1 very cracked plug. Again thank you all for your help. What makes it even better is now my clutch is broken in so I will be 
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