ECMlink Bad front O2 sensor? Logs.....

[jjw205]

Do I have a bad front o2 sensor? The car is perfect on cruise. but very lean at idle, and for some reason it randomly shoots to 14-15 AFR at WOT! The WOT log shows the front o2 voltage wacky, but why would the cruise log be perfect?

Pretty confused on this one...

Any help would be great.

 

[DeadlyScone]

The o2 should only see .40 and .80 might be worth it just to replace it, those voltages are funky. Your car goes into open loop so the car does not use feedback from the o2 in WOT or open loop

 

[jjw205]

The o2 should only see .40 and .80 might be worth it just to replace it, those voltages are funky. Your car goes into open loop so the car does not use feedback from the o2 in WOT or open loop

I know, that's why I can't figure it out. Cruise is perfect. But when the front o2 voltage goes wacky, my wideband starts reading 14's and 15's at WOT. That's the scary part. I didn't think the front o2 had anything to do with open loop.

 

[snowborder714]

I didn't think the front o2 had anything to do with open loop.

It does. Check out the bullet points under 2g open loop mode.
fueltrimupdatepoints [ECMTuning - wiki]

It is cycling, but isn't going high enough to seem like it's working properly. Just get a new one and throw it it and see if it is better.

 

[jjw205]

It does. Check out the bullet points under 2g open loop mode.
fueltrimupdatepoints [ECMTuning - wiki]

It is cycling, but isn't going high enough to seem like it's working properly. Just get a new one and throw it it and see if it is better.

Thank you.

OK, just ordered one from RockAuto. Only $33 from them for a Bosch, beats $57 locally at Advance Auto!

I actually forgot I had the CEL for the O2 disabled in Link, thats probably why that didn't come on

I don't understand why I wasn't getting any knock at WOT running 14-15 AFRs though....

 

[jjw205]

I ordered an O2, but in the meantime I tried to simulate the front O2 with my wideband. It still does the exact same thing... you can see it go lean at about 4600RPM. I have no idea whats causing this. If it was a bad front O2, would it still do this while simulating with the wideband? Could it be something else?

 

[c2ypt1c]

Have you checked for pre-sensor exhuast leaks?

 

[jjw205]

Yes, double checked everything. Like I said, its fine at idle, cruise, and its OK at WOT until about 4600 rpm and then it just goes straight lean. Maybe an ECU issue?

 

[snowborder714]

Seeing your log and how the wideband just goes lean, I'd guess either a boost leak at higher psi or a fuel delivery issue. Or maybe some issue/setting with the meth controller that's causing it to go leaner than anticipated.

 

[jjw205]

Seeing your log and how the wideband just goes lean, I'd guess either a boost leak at higher psi or a fuel delivery issue. Or maybe some issue/setting with the meth controller that's causing it to go leaner than anticipated.

Yea, I can't figure it out. I checked for boost leaks, but wouldn't that make me run rich instead of very lean? Even if something happened with the meth controller (controlling thru Link), i would assume it would run what the target AFR is in the map (12s) regardless.

Not sure what to try next.

 

[snowborder714]

Have you done a pull without the meth enabled just to see what happens? I feel that this is a mechanical issue and not an ECU/tuning issue. Nothing looks weird in the logs to me.

 

[jjw205]

Have you done a pull without the meth enabled just to see what happens? I feel that this is a mechanical issue and not an ECU/tuning issue. Nothing looks weird in the logs to me.

No I haven't, I will try that next. Thanks.

I was thinking about doing that, but when it goes lean, I like the meth in there as a safety factor. But I guess I can let off right when I see it go lean.

It's worth a shot at this point, I'm running out of options.

 

[snowborder714]

If you see if go really lean, obviously get off the gas.

 

[jjw205]

Yea, that's the scary part. I didn't even notice it until I looked at one of my logs. Idk how I wasn't getting any knock though.

It's just strange that it happens right at 4600rpm every single time.

The methanol turns on at 3500, and you can see by the AFRs that its flowing.

But I'll give it a shot without it enabled and report back.

Thanks again.

::::::EDIT::::::

I just realized, my FPS is set to be enabled at 4500rpm, and at >86% TPS, right where my problem is happening. Idk how it got changed, but I think this is my problem.

I will take it out for a drive tomorrow to confirm.