colder IAT's result in Hanging Idle possible?

[carlrx7]

Since the temperature has dropped from the 90's down to the 60's, my idle has started to hang.

i recently raced a z06, and have noticed it since.

should i be go back and retweak my RAF table? or should i start looking for a vacuum leak?

i haven't put a scan on it yet to look for some out of wake fuel trims.

i go wot from 2k rpms and my wide band doesn't got stupid rich to indicate any positive trims.

just would like to know if its required to retune the RAF in the winter time.

i tried to find an IAT vs raf idle table but can't find it.

Thanks

-Carl

[IDRIVEAG8GT]

Sounds like your Minimum Idle airflow tables are borderline. If not, what's your Engine Coolant Temp? Could be referencing a table with an odd value for that particular temperature? My vehicles constantly range from 60 to 100 with no issues, unless, your IAT Modifier table is adding spark when it drops too low. The resulting timing increase may add too much table for the ECM to command the correct idle at. Yes/No?

[carlrx7]

Just checked the IAT map and all the multiplyers,

not adding any timing for cold weather conditions in the lower g/cy and lower rpms range.

[carlrx7]

Did some tuning last night and it took about 10 tunes before i got the idle to come down and go directly to idle without hanging.

here is how much airflow i had to remove to accomplish this.


please note, the last time i tuned the raf table was in august when it was ballz hot out and the idle never hung then,

but now its in the 60's and it started hanging. wtf.. i thought running a MAF i could set it and forget it.

attached is the table for the amount i had to take away. and also is the last scan i did with a quick drive around the block, and bills config i used.

-Carl

[carlrx7]

bump

[IDRIVEAG8GT]

Bump bump, so wait s sec? Does that mean you will have to go back and forth between tunes from season to season??

[carlrx7]

i hope not. FML

[IDRIVEAG8GT]

Just throwing this out there, but wouldn't a properly tuned MAF be able to reference the table with low and high enough numbers to correct all future "Screw ups" like this? I thought that's what EFI was all about....

[carlrx7]

maybe its a mechanical issue.. im gonna take a look to see if the tb needs cleaning..

-Carl

[IDRIVEAG8GT]

maybe its a mechanical issue.. im gonna take a look to see if the tb needs cleaning..

-Carl

That brings me back to a point, if your TB comes back clean, then maybe you Minimum Idle Airflow is Bd'd for your idle speed.

[IDRIVEAG8GT]

Wait you're calling RAF what I call Minimum Idle Airflow. Now I feel stupid. Oh well, shouldn't the values look like the attached thumbnail I posted?

[carlrx7]

mine is the comparison between the previous tune which was fine in the hot weather but had issues with hanging idle and cruise control(aka car doesn't slow down when you take your foot off the gas. and the tune i just did to correct it all.

also your is in lb/min and mine is in g/sec

[IDRIVEAG8GT]

mine is the comparison between the previous tune which was fine in the hot weather but had issues with hanging idle and cruise control(aka car doesn't slow down when you take your foot off the gas. and the tune i just did to correct it all.

also your is in lb/min and mine is in g/sec

Yeah I gotcha now. Sorry I had a Brain fart. But anywho, I see that. Why the hell is yours a different value?

[Gh0st]

It's your RAF. Had the same issue long time ago with my GTO.

[carlrx7]

funny, its 83 degrees in charleston now, and trying to stall again. WTH! Now I need to go back and bump up the RAF again? theres got to be another table to adjust..

-Carl

[IDRIVEAG8GT]

You need to adjust both the ETC multiplier and also Baro Multiplier to correct the issues. I did alot of research over the winter.

[carlrx7]

do what to what?