Need help
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2nd Gear
Joined: Aug 2025
Posts: 2
Likes: 1
Need help
I bought a 1998 Ford F150 XLT 4.6L as another old work truck. I have some codes pulling, a P0303, P0420, P0304, and a P0171. After getting it home I got out and heard some popping on the passenger side, I looked up under it and the pre cat and cat were both glowing red. Could this be clogged cats that are causing the misfires on cylinders 3 and 4 due to back pressure on that bank?
More Turbo
Joined: Mar 2009
Posts: 532
Likes: 92
I bought a 1998 Ford F150 XLT 4.6L as another old work truck. I have some codes pulling, a P0303, P0420, P0304, and a P0171. After getting it home I got out and heard some popping on the passenger side, I looked up under it and the pre cat and cat were both glowing red. Could this be clogged cats that are causing the misfires on cylinders 3 and 4 due to back pressure on that bank?
clogged, or a lean condition
Fleet Mechanic
Joined: Jun 2023
Posts: 1,352
Likes: 373
From: WA
Unburned fuel from a misfire ends up in the converter. So a lean misfire can actually cause excess fuel in the converters. If they were red hot they might already be ruined.
The misfires probably caused the glowing converters, not vice-versa.
There are ways to tell if the exhaust system is plugged. Good luck.
The misfires probably caused the glowing converters, not vice-versa.
There are ways to tell if the exhaust system is plugged. Good luck.
Thread Starter
|
2nd Gear
Joined: Aug 2025
Posts: 2
Likes: 1
Unburned fuel from a misfire ends up in the converter. So a lean misfire can actually cause excess fuel in the converters. If they were red hot they might already be ruined.
The misfires probably caused the glowing converters, not vice-versa.
There are ways to tell if the exhaust system is plugged. Good luck.
The misfires probably caused the glowing converters, not vice-versa.
There are ways to tell if the exhaust system is plugged. Good luck.
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