hard time cracking this idle issue

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10-02-2013
bjlindell

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hard time cracking this idle issue

I am currently tuning a H/C 1999 Trans Am

It is a SD tune i am working on. I have spent a couple hours without a WB trying to get this car to idle and even rev.
it has been doing some very weird "revs" on its own to about 2000rpm while monitoring IAC being at 0 counts...
the biggest concern is that is hits 0 dyn cylinder airmass. you can hear it when it does that and inj pulsewidth is near 0 when it happens...

I dont know what is causing it to do that.

(i understand my throttle position is at the .75 volt mark and that i should be using a WB...)

attached is the log and tune and a picture to point out what im looking at

THANKS for any input

Attachment 41260
Attachment 41261

Attachment 41262
10-02-2013
Ben Charles

Fueling is off and the IAC is zero most likely due to the TB open up too far, plus you need to be scanning much more variables for idle.
10-02-2013
Russ K

Ok, your not in SD mode as there has to be a Maf DTC to be in SD mode. Plus your Maf table is zeroed, I'm surprised that the engine will even start.
Change the Maf codes to 2-no mil.

Russ Kemp
10-03-2013
bjlindell

Quote:

Originally Posted by Ben Charles

Fueling is off and the IAC is zero most likely due to the TB open up too far, plus you need to be scanning much more variables for idle.

Ill have to get the throttle voltage below .75v
Thanks to Russ K I would usually be using his config and a little extras for scanning variable such as WB or what not...
any extra variables you think I should be looking at to help? I feel lost on tuning idle spark...

Quote:

Originally Posted by Russ K

Ok, your not in SD mode as there has to be a Maf DTC to be in SD mode. Plus your Maf table is zeroed, I'm surprised that the engine will even start.
Change the Maf codes to 2-no mil.

Russ Kemp

I guess i never understood that there had to be a MAF DTC for it to be in SD mode. Makes sense now. but should P101, 102 and 103 all be set to 2-no mil?
I zeroed my maf table to ensure the maf failed and wasnt ever looking at that table for fueling.
I make sure the maf table isnt zeroed out now and make the DTC changes and go from there.

Thanks for the input guys!
appreciate it