Hot Startup: Very Lean for a few minutes...

[mattster03]

Just a very general question. Yesterday I was working through my VE table in openloop for the very first time. Basically using my wideband error histogram trying to get a decent tune for 0-4000 RPM portion of the table. After using the multiply by % function I would reflash my tune and start up the car. My wideband would read extremely lean (like 15.5-16.0) for what seemed to be 4 or 5 minutes then suddenly it seemed everything would go back to normal and I would continue to tune my VE table.

Has anyone else experienced this? I did a little searching and really haven't couldn't find if this is normal or an explanation as to why. The car would only sit for 10 minutes or so and I let my NGK AFR wideband warm up for the 20 count before starting. Any help is appreciated

I know that I haven't posted my tune and log, but I am hoping this is just more of a general question. The reason I don't have the log is because I didn't start logging until everything "normalized".

[mattster03]

I am beginning to wonder if it's because my IAT is getting heatsoaked? I was thinking that if my car was truley in open loop my tune shouldn't be affected by IAT's?

[domestic rice]

I know my nb or wb dont work worth a crap at idle. My car also leaned out a bit when the IATs got up there until i messed with the BIAS settings a little. No problems since.

[wokaz]

Im seeing the same thing doing the same thing! Once a quick squirt, idle floats around commanded. At startup it's meant to be richer (in my tune anyway) but it reads leaner! Im starting to dig into it so interested in this thread also...

[LSXstang94]

anyone ever solve this?

[bradw18]

old post. any body ever solve it??

[lwrs10]

its caused by heatsoak, and is very common on OLSD cars. You can add a bit to the hotsoak enrichment table to help out with it, or fix it correctly with a mix of cyl bias and hotsoak tables. One easy way to help out is bias the cyl bias table closer to ECT, and farther away from the IAT. There is a few more tables in the PCM HP Tuners does not have that are related to this too.