At idle OL AFR good, CL 16 AFR

[Beer99C5]

I have a LC-1 WB and am messing with EFI Live, I have been expierencing a lean at idle for quite some time (factory tune), at first I thought the WB was off, but it has proven to be pretty accurate (testing based on bidirectional controls and commanding a 12.5 and a 14.6 and it tracking to w/i a .1).

I swapped to 42 lb injectors and was pleased to see it start it up and see it idle at 12-14 AFR in Open Loop (it is w/i .1 to .5 commanded AFR in OL). After it warms up (assuming the O2 sensors are whats warming up) it goes to CL and pretty much climbs to and maintains a 16 AFR, despite the Commanded being 14.X

Being CL relies on the O2's is it safe to say they are the problem? The car has 50k on it and is stock (other than the 42# injectors). If it is the O2s, should I start with the front ones to see if that cures it? The car is not setting any codes.

The other option I see is the O2's are using the STFT, maybe disabling those with help?

Here is the log if anyone is interested (frame 620-650 is where it transitions from OL to CL and climbs to 16 AFR)

http://www.retrorelics.net/jim/Boards/EFILive/10_16_2006Stock42sOLtoCLAFRissue.efi

[Black02SS]

This is one of the reasons I do not like O2's. I would tune the car in open loop, get some new o2 sensors if you want, and then throw it in CL to see how it does.

[SSpdDmon]

You could try setting 4105 to 550 across the board and see if that helps any??? Also, try setting B3607 to 14.7???

[Beer99C5]

Thanks I will give it try tommorrow, wife put me to work today so I could not play:frown:

[dc_justin]

Is your wideband calibrated properly? With it spiking up to 20:1, I would expect your RPMs to stumble a bit more than what we're seeing.
Example, when my engine is cold in SD mode, (OL Multiplier not working properly), and I blip the throttle, my rpms will actually DROP before raising as AFR sails up to 20:1.

[Beer99C5]

You could try setting 4105 to 550 across the board and see if that helps any??? Also, try setting B3607 to 14.7???

Seems 4105 set to 890 or so, brings it down to low 15's.

Is this OK or should I try some new O2's?

Is the center of the narrowbands (14.6) the mid voltage of 550?
By putting them at 890 to force the idle to low 15's is that OK?

Should I leave it at 16 for the AFR at idle and not worry about it?

[dc_justin]

Seems 4105 set to 890 or so, brings it down to low 15's.

Is this OK or should I try some new O2's?

Is the center of the narrowbands (14.6) the mid voltage of 550?
By putting them at 890 to force the idle to low 15's is that OK?

Should I leave it at 16 for the AFR at idle and not worry about it?

550 sets you a hair on the rich side... 450mv is the switch point from lean to rich.

[Beer99C5]

Hooked up a Predator to check my fuel trims (laptop was in the house) and was watching the O2's and noticed that Bank 2 sensor 2 was not updating like its counterpart, Bank 2 passenger side sensor 2 the one behind the Cat? Is this likely the culprit???

[dc_justin]

Hooked up a Predator to check my fuel trims (laptop was in the house) and was watching the O2's and noticed that Bank 2 sensor 2 was not updating like its counterpart, Bank 2 passenger side sensor 2 the one behind the Cat? Is this likely the culprit???

AFAIK, rear O2 sensors are never used for fuel trimming...

Do you free-air calibrate your WBO2 frequently enough?

[Beer99C5]

I am satisfied that the problem is not the WB.

What I said was I noticed the one sensor not functioning like its twin, it was sensor 2 bank two. I was not attempting to use that sensor to monitor the trims, I was looking over everything the Predator scans and the one O2 stuck out like a sore thumb. Funny thing is there is no code being thrown for it.

Let me reprase the question, would a bad rear O2 sensor cause me to run lean at idle CL?

[TAQuickness]

nope. BxS2's are for measuring catalyst effeciency.

[BACKinBLACK]

where is your wideband sensor located at? down line of the cat or before the cat

[Beer99C5]

Before the Cat, just behind the fwd factory O2, passenger side

http://www.retrorelics.net/jim/Boards/Corvette/LC1c.JPG

[98SS2836]

Are you running the MAF by any chance?

[Beer99C5]

Yes, what I would like to do is keep the MAF, as I want to spray a 100-150 Dry shot from time to time.

[98SS2836]

Yes, what I would like to do is keep the MAF, as I want to spray a 100-150 Dry shot from time to time.
Thats probably why it's lean the MAF needs to be corrected.

I cant even run a maf on my car. Car hates it no matter what I do. I made the same exact power with MAF CLSD OLSD. Same power curve everything. It drives better in OLSD.

[Beer99C5]

Is the car using the MAF at idle in CL?

[Bruce Melton]

I am still betting on an exhaust leak. You have the same symptoms I had and it was a tiny leak which when fixed brought everything in line--

[98SS2836]

Is the car using the MAF at idle in CL?

Un plug the maf and see what the A/F Is if the car doesn't use the maf at idle it shouldn't do anything when you unplug it right?