Open Loop with Electronic Throttle and IAT in MAF

[deezel]

I have seen many of the posts about how to setup open loop with ETC and IAT in the MAF. I really didn't want to pull the wires out of my MAF, so I tried to setup open loop with the MAF still connected. Here's what happened...

First, I did all the stuff in the Autotuning tutorial - disable MIL for P0101,0102,0103 codes, set MAF fail to 1, and so forth. I started running the tune, and everything seemed fine at first. I took it easy for a few blocks, keeping an eye on the AFR and KR readings. When I got to a freeway access road and gave it some throttle, the engine went into Reduced Power Mode. This was a little scary because it was unexpected. Turns out I set the P1514 code for ETC airflow not matching the "actual" airflow being commanded by the VE table in open loop. My VE table was off far enough in a few spots to cause this.

So, my next step was to disable the P1514 code, the MAF codes (0101-0103), and the B4206 "Use O2s with Open Loop" setting. This fixed the Reduced Power Mode, but caused another problem. By turning off the MAF codes (disabling by setting to "not reported"), I prevented the engine from dropping into full open loop. It was still using the MAF reading, even though my intention was to run open loop. So, I ran a bit lean for a tune or two until I realized this because my VE changes were not changing the fueling.

Finally, I found a combination that worked. I had to turn the MAF codes back on, but leave the P1514 code turned off. Now it goes into full open loop mode without setting the P1514 and without using the MAF. I can still see the MAF reading, but now it is definitely fueling based on the VE table and the commanded AFR table. It still sets the P0103 code for the MAF fail frequency (which is what puts the PCM into open loop), but I still have the MIL turned off. I left B4206 diabled.

For those with ETC, keep the P1514 code in mind (table C6101).

For those with the IAT in the MAF sensor, it does seem possible to run full open loop without cutting/pulling the wires for the MAF signal. I suppose this might apply to non-IAT MAF's as well.

Now I just need to finish this autotune and verify my BEN factor so that I can fix the crappy MAF calibration...

Happy tuning.

[bink]

Or...........set both the MAF High Freqency Fail 1 {C2901} and the MAF High Freqency Fail Limit {C2902} to "1". This insures that it drops into SD at the 1st failure.

And..........multiply C6101 by 200%.
Leave the MAF alone and you should be good to go.

Cheers,
joel

[deezel]

I did set the fail limit to 1, that was part of the "and so forth" ...

I think I will increase both the C6101 and C6102 for good measure. I'm about to go flash the closed loop SD tune now...

cheers