running rough
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Joined: Nov 2015
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running rough
just finished installing complete exhaust. headers midpipe and mufflers. went for a test driveand it sounds great and ran perfect for about a mile then started running like it was on 4 cylinders. shut it off then started it back up and ran perfect for about the same distance. restarted in the garage and runs perfect then I just shut it off. any ideas on the cause. It threw no codes
Burning Brakes
Joined: May 2013
Posts: 1,249
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From: Lynn MA
You added headers, when I did I ended up with two wires that got burnt through. Had to pull them all off to find the bad ones. My car was doing the exact same as you described.
1/4 mile/AutoX
Joined: Jun 2014
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From: Buffalo Texas
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I changed the plugs and wires. started it up and it runs perfect for a minute or two then rough as can be. I turned it off and restarted it and it runs perfect for a minute or two. so i turn it off and restart immediatly and it runs great so i just shut it off. i have no clue whats going on
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Joined: Nov 2015
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I cleared all the codes. started it after a minute it began running rough . I left it running and there are no codes. the starter is good for sure. Its hard to tell about the other grounds but they appear to be ok
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I had the exact same issue after a header install. All looked fine BUT,,, once you dug a little deeper, THIS is what you could fine:
You do NOT have to have a TUNE but,,,,,,,, you will NOT get all the HP/Tq that is on the table from what the header install has to offer and you will loose a little fuel economy until it tuned.
When the engine starts running rough, LOOK at the Check Engine Light. See if it is FLASHING. If its flashing, that indicates a cylinder or multiple cylinder misfires. IF,,,,, you pull up the DTCs "WITHOUT turning off the ignition, you will or SHOULD see a P-300 (misfire DTC).
Bill
You do NOT have to have a TUNE but,,,,,,,, you will NOT get all the HP/Tq that is on the table from what the header install has to offer and you will loose a little fuel economy until it tuned.
When the engine starts running rough, LOOK at the Check Engine Light. See if it is FLASHING. If its flashing, that indicates a cylinder or multiple cylinder misfires. IF,,,,, you pull up the DTCs "WITHOUT turning off the ignition, you will or SHOULD see a P-300 (misfire DTC).
Bill
Last edited by Bill Curlee; Jul 12, 2016 at 09:44 AM.
Burning Brakes
Joined: Oct 2014
Posts: 874
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From: Detroit MI
When I installed my headers, I replaced the plugs and wires. It was running about as you described, and I started to panic. So I pulled all the wires off and sure enough, I managed to crack one of the brand new spark plugs. Replaced it and it was fine. It's absolutely worth double checking that they're all ok, and heat socks on the wires are a great idea as previously mentioned.
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I put on new exhaust because I was having trouble with leaks and rattles. It is tuned for headers. I replaced the new plugs and wires with even newer plugs and wires. what I don`t get is why it runs perfect for a short time then runs bad I shut it off and immediatly start it and it runs perfect again. no codes or check engine light
