Programming out fuel composition sensor?

[camy]

First, let me say that while I've purchased EFILive, I've not yet used it. I bought it (got a combo deal with WB O2 sensor) for an '98 LS1 swap into an old Corvette, but I'm not to the tuning point yet.

I've also got an '02 Yukon with the 5.3l flex fuel fuel engine. I'm getting the P0178 code indicating a potential bad fuel composition sensor. After pricing the sensor ($500ish), I'm wondering two things:
1) Can I tune it so the E85 maps aren't used?
2) When this code is detected, what maps are used? Could I tell by scanning?

It seems to run fine, and I assume that it uses the regular gas maps since E85 isn't too common. OTOH, the E85 needs a richer mixture, so maybe it's safer to default to the E85 tune??

[vatman02]

you should be able to just unplug the sensor and turn of mil light for the faulty sensor. mine is p0177-p0179 change them to not reported in the mil enablers and processesing enablers tabs. once the sensor is unplugged, even if it's faulty, it can't make can't cause changes and the truck should run fine.

[Aint Skeered]

I am doing this on my brothers Suburban since we dont have the e85 here in Louisiana except for a few places. I tuned the whole b3601 table to 14.63 and unplugged the sensor. Problem is the burb has been running rich for so long that it is in serious need of a tuneup and still runs like crap.

We scanned it last night and the bank 1 ltft is staying 25% while cruising while the bank 2 shows around 2-5%.

My guess is bad o2 sensors and fouled out plugs but instead of commanding 12.2/1 af it is now commanding 14.63 untill pe kicks in. When he floors the pedal, the truck just noses over with no power at all. even cruising he is having to give it lots of throttle.

Just to make sure , we are going to check for vacuam leaks on the intake today by shooting carb cleaner around the intake and watching the ltft and o2 sensors .

Any other tips?

[nevinsb]

There is a default ethanol % value in one of the tables, but I don't have the software in front of me, so I can't look up the number. If removing the sensor, you should set that to 0% or 10% or whatever your fuel is.

[Aint Skeered]

any one know the table?

[nevinsb]

Not sure what year Suburban you have, but on the 2004 S10 PCM:

B5947: 0.0
B3660: 0.0
B3601: 14.681005
B3101: NO
B3103: 0
B3104: 155
B3105: 45

[Aint Skeered]

thanks, I am also thinking of turning off his o2's and running open loop to see if it is his o2's screwed up causing it to run 25% ltft on the drivers side. Is this going to cause anything else that i need to watch out for?

I set b3801 to disable. Without the o2's correcting , Will it get lean if the problem is elsewhere?

[nevinsb]

If this is happening on just one side, I think you have something else going on there. Maybe a leaking intake manifold gasket or fuel pressure regulator, bad injector, bad catalytic converter, bad 02 sensor, or exhaust leak.

[dfe1]

Before you spend a lot of time chasing O2 sensor problems, check for mechanical problems-- vacuum leaks, faulty injectors, bad fuel pump, etc. On a number of vehicles, I've seen big differences in left- to right-side LTFTs caused by these types of problems. It almost seems like the PCM is altering fuel trims as a means of diagnosing the problem, or maintaining reasonable drivability. I specifically remember a few situations when fixing a manifold leak (which would have affected cylinders on both banks) brought side-to-side fuel trims back into alignment.