Misfire code p0308 only in overdrive
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2nd Gear
Joined: Dec 2024
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Misfire code p0308 only in overdrive
1997 ford f150 4.6l with a 4r70 transmission fully stock from factory including transmission fluidbut fluid color is still red/pink it has around 75000 miles on it.
So last weekend I took my truck to Kansas about halfway there it got a lot of transmission shudder and it threw the code p0308 which is a misfire code on cylinder 8 replaced coil pack and spark plugs, wires tested fine. Still threw the code after all of that. Then I took it out cleared the codes once again and it didn't throw the code tell I hit about 45-55 mph with alot of transmissions shudder. Cleared the code again this time and took overdrive off and it drove just fine over 3 hrs back to my house never threw the code never had transmission shudder. This is the most confusing fix I've been trying to chase down for the last 5 days. I'm about to do a transmission service on it to try and see if it's worn out/old transmission fluid.
So last weekend I took my truck to Kansas about halfway there it got a lot of transmission shudder and it threw the code p0308 which is a misfire code on cylinder 8 replaced coil pack and spark plugs, wires tested fine. Still threw the code after all of that. Then I took it out cleared the codes once again and it didn't throw the code tell I hit about 45-55 mph with alot of transmissions shudder. Cleared the code again this time and took overdrive off and it drove just fine over 3 hrs back to my house never threw the code never had transmission shudder. This is the most confusing fix I've been trying to chase down for the last 5 days. I'm about to do a transmission service on it to try and see if it's worn out/old transmission fluid.
Last edited by Zaquiri; Dec 24, 2024 at 04:14 PM.
Hotshot
Joined: Jul 2020
Posts: 10,456
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From: Near Salt Lake City
His 97 will have plug wires
Hotshot
Joined: Jul 2020
Posts: 10,456
Likes: 2,630
From: Near Salt Lake City
I'd sure check the plug wires, and inspect the #8 plug (it's a Motorcraft spark plug, correct?)
The plug wires should be roughly 7500 ohms per foot
The coil packs like to fail
Maybe switch those two coil packs as a test (look closely for carbon tracks around the #8 coil terminal first)
Take a photo or use google to make sure and get the wires back on there correctly if swapping coils to test
The plug wires should be roughly 7500 ohms per foot
The coil packs like to fail
Maybe switch those two coil packs as a test (look closely for carbon tracks around the #8 coil terminal first)
Take a photo or use google to make sure and get the wires back on there correctly if swapping coils to test
Hotshot
Joined: Jul 2020
Posts: 10,456
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From: Near Salt Lake City
Visited Maine in September this year, beautiful place to say the least, got a lobster roll from Reds. We visited "the end" and the little lighthouse up the road, also Bar Harbor. Marvelous, just marvelous
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Cross-Country
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We love it here ! Maine has so much beauty.
The locals hate Red's because it's too successful and causes traffic problems LOL. Best place to go, imho.
The locals hate Red's because it's too successful and causes traffic problems LOL. Best place to go, imho.
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2nd Gear
Joined: Dec 2024
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So sorry I've been Hella busy with work but I check the wires by swapping 7 and 8 plug wires and the code stayed on 8 so now I'm about to swap 7 and 8 injector to see if that's the problem. BTW checked for vacuum leaks around the intake and there wasn't any from my checks but if you guys have any other test or suggestions let me know thank you all for at least leading me away from the transmission
Last edited by Zaquiri; Dec 29, 2024 at 04:25 PM.
Fleet Mechanic
Joined: Jul 2019
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Just pull the plug and “read” it.
ETA: I guess you didn’t do that with the last set. I guess you can swap injectors, but a compression test should go in as well. If that truck has 75,000 miles on it, cool. But, 27-year old engines need love, too.
ETA: I guess you didn’t do that with the last set. I guess you can swap injectors, but a compression test should go in as well. If that truck has 75,000 miles on it, cool. But, 27-year old engines need love, too.
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