King Salami
20+ Year Contributor
- 170
- 4
- Jun 27, 2002
-
Oklahoma City,
Oklahoma
I'm having a heck of a time tracking down why my fuel trims are all maxed @ 139 while the car seems to be running rich. My exhaust smells pretty rich (when the engine is warmed up), my exhaust pipe is carboned up, and I get a burble when I decelerate and an occasional pop out the exhaust. My idle occasionally drops off enough to stall when the engine is hot. It only happens when the ECU is in closed loop – the car runs better before the O2 sensor warms up & starts talking to the ECU. I suspect an exhaust leak, but I can't find it.
I looked at my plugs, but they seem to indicate a lean condition (very light grayish tan).
The O2 sensor is brand new and cycles just fine.
I've checked for boost leaks – no major leaks.
The ISC and EGR are operating properly.
My adjustable FPR and fuel pump seem to be OK. Initially assuming I was running lean, I bumped up my fuel pressure, but that seemed to make matters worse.
I looked around my exhaust manifold, turbine housing, and downpipe for leaks by running Seafoam through the engine and by plugging the exhaust pipe while the car is running, but I could not locate any leakage (after I fixed a leak between the turbine housing and manifold).
After the Seafoam, my knock count (initially around 20-25 counts at 15 psi) went down considerably. I'm assuming the carbon from running rich was cleaned out by the Seafoam. But after about 2 weeks, the 20+ knock count at 15 psi was back.
I reset the ECU, and the car ran better until all 3 fuel trims inched back to 139.
Another odd indication is that the range of my O2 trim under normal driving is from 38 to 167. While cruising on the freeway, the O2 trim oscillates from 102 to 124, with an occasional peak to 140-167.
Any ideas?
I looked at my plugs, but they seem to indicate a lean condition (very light grayish tan).
The O2 sensor is brand new and cycles just fine.
I've checked for boost leaks – no major leaks.
The ISC and EGR are operating properly.
My adjustable FPR and fuel pump seem to be OK. Initially assuming I was running lean, I bumped up my fuel pressure, but that seemed to make matters worse.
I looked around my exhaust manifold, turbine housing, and downpipe for leaks by running Seafoam through the engine and by plugging the exhaust pipe while the car is running, but I could not locate any leakage (after I fixed a leak between the turbine housing and manifold).
After the Seafoam, my knock count (initially around 20-25 counts at 15 psi) went down considerably. I'm assuming the carbon from running rich was cleaned out by the Seafoam. But after about 2 weeks, the 20+ knock count at 15 psi was back.
I reset the ECU, and the car ran better until all 3 fuel trims inched back to 139.
Another odd indication is that the range of my O2 trim under normal driving is from 38 to 167. While cruising on the freeway, the O2 trim oscillates from 102 to 124, with an occasional peak to 140-167.
Any ideas?
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