Very lean Idle with ATI SC
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Very lean Idle with ATI SC A friend just installed a ATI SC on his 99 C5.
Installed SVO 42 injectors and PCM tuned.
Few weeks ago he went to the drags and only ran like 12.4 ETs at like 110 MPH. LTFTs were -3% rich. WOT timing at 17 degrees at 7 PSI boost.
After that the car surges all the time, at idle the LTFTs are 25% yet at part throttle they are close to zero. O2s at idle are around zero but trip no DTCs and seem to report correct mVolts at part throttle.
He gets AIR pending DTCs on right head.
IAT is like 150 degrees when it is 75 degree weather.
So what would cause idle to be so lean when SC I assume is doing very little at idle RPMs ?
Thanks,
Installed SVO 42 injectors and PCM tuned.
Few weeks ago he went to the drags and only ran like 12.4 ETs at like 110 MPH. LTFTs were -3% rich. WOT timing at 17 degrees at 7 PSI boost.
After that the car surges all the time, at idle the LTFTs are 25% yet at part throttle they are close to zero. O2s at idle are around zero but trip no DTCs and seem to report correct mVolts at part throttle.
He gets AIR pending DTCs on right head.
IAT is like 150 degrees when it is 75 degree weather.
So what would cause idle to be so lean when SC I assume is doing very little at idle RPMs ?
Thanks,
Adkoonerstrator
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From: Deep in the seedy underworld of Koonerville
Re: Very lean Idle with ATI SC It may be from the MAF location with the ATI kit.
See this thread for a little info. I'll try and find some other threads about this.
https://ls1tech.com/ubb/cgi-bin/ulti...;f=20;t=000475
On my car the idle Ltrims were like 18% but, they got even worse at part throttle. His may be going to zero at part throttle because of the programming and big injectors???.
I changed the MAF location and BLAMMO everything was perfect. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
John
See this thread for a little info. I'll try and find some other threads about this.
https://ls1tech.com/ubb/cgi-bin/ulti...;f=20;t=000475
On my car the idle Ltrims were like 18% but, they got even worse at part throttle. His may be going to zero at part throttle because of the programming and big injectors???.
I changed the MAF location and BLAMMO everything was perfect. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
John
Re: Very lean Idle with ATI SC Forced induction is WAAAYYY harder to tune for than n/a or n20. You have to start slowly and work your way up as we generally dont get a second chance with tuning
