[Z06] new intake do i need a tune????
Melting Slicks
Joined: Apr 2000
Posts: 2,920
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From: North Bend WA
Le Mans Master
Joined: Dec 2005
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From: Communist Colorado
Hey you guys that had the CEL come on, .....How long did it take to come on? Was it immediate or days, weeks??? I just put my Halltech on yesterday & took it for a 14 mile or so drive with no light yet. I let it warm up real well also. (had'nt started it in a few days prior) also no light during warm-up.
Le Mans Master
Joined: Jun 2001
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From: Admit Nothing, Deny Everything, Make Counter Accusations.
The only way to correct this situtation is with programming. Changes in ambient conditions can also cause a shift in LTFT and STFT. This may turn the CEL on or off if you are close to throwing a code.
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Melting Slicks
Joined: Apr 2000
Posts: 2,920
Likes: 2
From: North Bend WA
Great explanation! 
However, the reason I ask is that numerous C5Z owners have reported allowing their PCM to re-learn and the codes stop showing up over time. This has been reported for the Stinger and also the Honker CAI's. I was just curious whether or not you had attempted that first.
However, the reason I ask is that numerous C5Z owners have reported allowing their PCM to re-learn and the codes stop showing up over time. This has been reported for the Stinger and also the Honker CAI's. I was just curious whether or not you had attempted that first.
Le Mans Master
Joined: Jun 2001
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From: Admit Nothing, Deny Everything, Make Counter Accusations.
That is not something that will be "learned out" The learning is basically STFT moving over to LTFT, with STFT trying to head back to zero. LTFT causes the codes in question. STFT is always jumping around, long trends in STFT cause a change in LTFT.
The learning process does not take too long to happen. Key cycles and run time determine the learning time. Ambient conditions can cause a shift in tuning and that might be why some airbox equipped cars see codes come and go.
The learning process does not take too long to happen. Key cycles and run time determine the learning time. Ambient conditions can cause a shift in tuning and that might be why some airbox equipped cars see codes come and go.
Last edited by RussBt; Mar 15, 2007 at 02:58 PM. Reason: Grammar
Melting Slicks
Joined: Apr 2000
Posts: 2,920
Likes: 2
From: North Bend WA
Thanks again for the information. It's definitely something for me to keep in mind as I consider CAI for my own Z06, and not wanting to invite trouble regarding PCM reprogramming and what that may mean for my GMPP warranty.
Le Mans Master
Joined: Jun 2001
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From: Admit Nothing, Deny Everything, Make Counter Accusations.
A stock Z06 in average 65 degree weather runs with about +1 to +5 LTFT in most load cells. LTFT is highly dependant on ambient conditions so this will vary. Change the airbox and you will most likely have undetected air sneaking by the MAF. The undetected air mixes with the initial fuel supplied by the PCM, which causes a temporary lean condition and may actually result in a slight power gain. O2 sensor closed loop feedback will report the lean condition while cruising and the PCM will attempt to fatten the mixture with more STFT. If the change in STFT hangs around long enough it will cause a change in LTFT. Changes in LTFT are designed to move STFT back near zero.
Your stock car that averaged +5 LTFT in most load cells may be up around +18 LTFT or more in most load cells after learning completes with the new airbox. The learning process will richen you up, which may take away some of the extra power you got right after you swapped airboxes. If the learning process causes LTFT to approach +20 you will get a trouble code. Additional airflow provided by the airbox at WOT and high RPM may give you more power if your tune (even the stock tune) is pretty good.
Your stock car that averaged +5 LTFT in most load cells may be up around +18 LTFT or more in most load cells after learning completes with the new airbox. The learning process will richen you up, which may take away some of the extra power you got right after you swapped airboxes. If the learning process causes LTFT to approach +20 you will get a trouble code. Additional airflow provided by the airbox at WOT and high RPM may give you more power if your tune (even the stock tune) is pretty good.
Melting Slicks
Joined: Jul 2006
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From: The 7th layer of hell - Western Washington
I went from stock to VaraRam to Honker and never got a CEL.
After I did full exhaust I got the typical O2 CEL cause of the high-flow cats, but that was expected and I have since tuned out the light...
After I did full exhaust I got the typical O2 CEL cause of the high-flow cats, but that was expected and I have since tuned out the light...
Safety Car
Joined: Sep 2003
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From: Hayward CA
