A0008 OL ECT Command Fuel Multiplier

[dc_justin]

I have a question regarding this OL ECT fuel multiplier... Should the effects of this be visible in the GM.AFR PID? Reason I ask is that I am seeing no effect from this table on my commanded AFR, causing me to be considerably lean during throttle application when cold... I've got 14.4:1 commanded and within a few seconds of startup it is already commanding that, while coolant temps say it should be commanding 12:1. Low rpm throttle blip results in a bog and 17-20:1 momentarily

[Tordne]

Should absolutely see the commanded AFR affected by the multiplier table!!! I use that table to enrich until the ECT comes up to 50*C.

I assume you are in fact in Open Loop? The enrichment you are seeing initially will/must be coming from the After-Start Enrichment tables.

[dc_justin]

Should absolutely see the commanded AFR affected by the multiplier table!!! I use that table to enrich until the ECT comes up to 50*C.

I assume you are in fact in Open Loop? The enrichment you are seeing initially will/must be coming from the After-Start Enrichment tables.

Yep, absolutely in OL. CL temp enable set to max value, LTFT Correction disabled, Commanded AFR table working like it should...

I knew that something had to be wrong there...

I might try re-flashing the entire OS and see if I've got a bug with it somehow right now...

[Tordne]

Figured I'd ask just in case. From your other posts I knew that wouldn't have been it, but you have to ask :)

Which Custom OS is it?

[dc_justin]

Figured I'd ask just in case. From your other posts I knew that wouldn't have been it, but you have to ask :)

Which Custom OS is it?

COS 3... 03190003 to be precise.

[dc_justin]

Triple and quadruple checked the tune file, then did another full flash.

Fired it up, Commanded AFR matched B3647 within a matter of 15 seconds. :(

[Tordne]

Email me the tune file if you like and I'll have a fifthruple check :)

[dc_justin]

Email me the tune file if you like and I'll have a fifthruple check :)

You've got mail. Current version of the tune and a log showing the issue.

[Tordne]

OK so I checked the tune, and all looks fine to me. Looking at the log it appears that that A0008 table is being ignored (as you say)!!!

The enrichment comes from the After-Start Enrichment and decays out as expected. The A0008 table should, in your case, hold the commanded AFR in the 12's till quite warm.

I'd PM Ross/GMPX and link him to this thread and email the tune/log to him as well.

[DrX]

I have noticed the same thing. Have tried everything to deal with cold starts in OL/SD. It's particularly bad when those cold starts can be as low as -40*C/F ECT(probably wouldn't run). Nothing seems to work well. Seems that an ECT VE multiplier might work better.

Anyway, my Commanded AFR goes straight to 14.79:1 (I have most of B3647 set to 14.7:1) and sticks there no matter what I have in A0008. I am seeing a very lean condition at idle or cruising(low airflow) until ECT warms up. IAT remains pretty steady throughout. Did seem that modifying A0008 was having some effect based on wideband AFR, although it was inconsistent.

[DrX]

Just tried A0008 again with a value of 2.0 for all ECTs up to 60*C. Ambient was -2*C. No effect on cold start AFR. Still goes lean until it warms up. I agree that it looks like this table is ignored.

[Tordne]

You can email me the tune if you like and I can take a quick look. I've used the COS's extensively and have had no issues whatsoever.. Email address is in my profile.

[dc_justin]

Yeah, they've been notified. I've tried 3 different COS versions, two for a 2003 and one for a 2004 in my truck, all with the same results.

If I have an opportunity, I'm going to try and get Ben Strader to bring a RR with him to his in-laws for Christmas, see if I can play with it and figure out what exactly will fix the problem.

In the meantime, I've come to the understanding that it will dip to 19-20:1 when I open the throttle for the first couple of minutes in SD. :frown:

[DrX]

My idle will also be lean until it warms up, then it goes rich. I have to keep the VE rich in this area(13.XX:1 AFR when warm) just to keep it from going leaner than 17:1 AFR. If I just do the AutoVE process as per the tutorial, idle is way too lean on cold starts, even in the summer. ECT seems to have a much greater effect on actual AFR than IAT when cold and at low engine speeds.

[Tordne]

How long is it staying lean for? Could you use After-Start Enrichment and extend the delay in the mean time?

[DrX]

How long is it staying lean for? Could you use After-Start Enrichment and extend the delay in the mean time?

It stays lean(gradually improves) until ECT gets to 50-60*C. Could be a while if I am starting form -20*C(0*F) or lower. We're talking minutes not engine revolutions. The normal after-start enrichment is done within 15 seconds of startup and would require a major bump to get a decent measured AFR.

Sent you my tune.

[dc_justin]

How long is it staying lean for? Could you use After-Start Enrichment and extend the delay in the mean time?

Staying lean until engine warms up a few more degrees, typically once I've made it 1/2 mile down the road or after 3-4 minutes. Afterstart enrichment doesn't last nearly that long :(