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Discussion Starter #1
I have a '96 4runner with a 2 gen S/C with URD pulley and fuel upgrade kit(not 7th injector). I am having a problem when I am driving around city, highway, or trail, and I let off the gas, the truck will run super rich, in the low 12's on the air/fuel ratio gauge. It gets too the point where I can smell the fuel going through the exhaust system, probably destroying the inside of my cat. Sometimes, I will get a P0172 CEL, which is a rich mixture reading code. And If I am going down a hill, while in gear, the truck will go right into open loop and run lean like it should, but as soon as it goes below a certain RPM, and the motor goes into closed loop, it will be rich again, untill I give it gas. Is this a problem with the tune? Maybe an 02 sensor? The motor has maybe 5,000 miles on it.

Live data from the scanner, at idle

ECT 195 degress
short term fuel trim -2.3 to 2.3
Long term fuel trim -18.0
O2 sensor 1 0.130 to .795
O2 sensor 2 0.065 to .870
TPS @ idle 12
Load % 14.1

My long term fuel trim is really fat, but why? Under WOT A/R is between 11.8-12.1, depending on load. Its only when I am idling down the road, like coming up to a stop light, when the truck running rich, like 11.2-11.8. If I put it in neutral and roll to the stop light, it will be very rich, then slowly lean itself out to 14.7-15.1.

No CEL.

I emailed URD and Gadget said I need a custom tune. But at the moment I am not wanting to drop 380 bucks an hour for dyno time on a truck that is mostly used and trailed to the trail.

Any ideas?
 

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Discussion Starter #3

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Need to tune. You tune in closed loop so the computer doesnt work so hard to maintain 14.7 AFR and to avoid engine lights.
 

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Have you opened and looked at your fuel table on the FTC? It sounds like you need to reduce the value of the cells to the extreme left of the table so that your are not dumping fuel into the engine during heavy vacuum. This is a trick I did on my blown Taco to help save on fuel. If I remember correctly I had mine set between 9.4-9.5, you don't want to them turn off completely ("0" values) because the ECU freaks out when you accelerate again and tries to compensate by dumping extra fuel.

RJM
 
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