Return to Closed Loop?

[WeathermanShawn]

Brad:

My brain is working again. I recall a similar problem on my 2002 Z-28. I had closed-loop enabled, but an O2 sensor read bad (too high) and by default it went into open-loop.

The difference was I got a DTC. I also have the front O2's set to 2 trips, Emissions-Related on all the Engine DTC Processing Enablers. In other words, all my C6001 Enablers are still stock.

I bet you are not getting a code since a lot of yours are set to 'Not-Reported'. I am 99% sure that a bad O2 will put you into Open-Loop Fault..

Anybody else have any ideas?

[DPS]

I was just reading through C6001 and stumbled across P0170 and P0173 (Fuel Trim System Banks 1 and 2) set as Not Reported.

Is that normal? Seems like this could be a problem.

The entire C6001 section might be effed for all I know. The initial tune wasn't based on a stock file. It's tough to find a stock tune for an LT1 car with a 0411 PCM.

-Brad

[WeathermanShawn]

I was just reading through C6001 and stumbled across P0170 and P0173 (Fuel Trim System Banks 1 and 2) set as Not Reported.

Is that normal? Seems like this could be a problem.

The entire C6001 section might be effed for all I know. The initial tune wasn't based on a stock file. It's tough to find a stock tune for an LT1 car with a 0411 PCM.

-Brad

Thats probably why there are no LTFT's plotted...

Seems like you have 2-3 options.

1. Keep it in SD Open-Loop. Reset B4205 to Max Temp (140C).
Set B3801 to Disable..

2. Keep it SD Closed-loop. Replace 1 or both Front O2 sensors..We could easily configure C6001 to operate normally..(I.E. my C6001 Tune would probably work..)..

Personally if this car will see some street, I would pick Option (2). Since your Table B3605 is already primarily set to stoich (14.63)..it would be an easy option.

I am sure with Joecar and crew, C6001 could be straightened out. It still looks like from your Log that the O2 sensors are not acting 'normal'. I assume that is mechanically-related and not because of the Tune (C6001). I think that just made the DTC not appear.

I would wait to see if you get some more reader/tuner feedback. Its an educated guess on why it won't go to closed-loop..but like I said I am pretty sure it involves C6001 and the O2 sensors..

We will get you some more feedback..

[DPS]

Thanks for the help.

Since the owner is picking it up today I've decided on Option 1. I'll just have to inform him that if he wants to drive it on the street he'll need to get a new O2 and an unmolested MAF and bring the car back.

Assuming he decides to do this, have you guys had any luck doing a MAF tune with a Granatelli or a stock descreened MAF? I ask this in case the owner hesitates at buying a new MAF.

-Brad

[WeathermanShawn]

Brad:

I have found the good ole stock GM MAF produces a fairly consistent and reliable frequency vs airflow (g/s).

You can get into massive Internet debates over 'de-screened' and "ported' MAF's. Some have big time problems, others seem to avoid them. I have tried all 3. I am back to the stock MAF. I just find it easier to tune for my application.

I will let others comment, but so far I have not found the stock MAF limiting my HP goals....

Good luck..

[mr.prick]

I've got a milled out stocker and have no problems.
I'm not sure what problems one would get from a non stock MAF,
you can always make adjustments to the MAF scale.