Why are LTIT's locked at -0.01?
07-13-2006, 10:51 AM
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Why are LTIT's locked at -0.01? I don't see how this is possible really, but I'm trying to help a guy figure out his idle problems, and his LTIT's are all at -0.01. His STIT's seem to be adjusting to help compensate, but the LTIT's never budge. Is this an indicator of something mechanical or is there something with the tune that I'm not aware of, that can effect this? The adaptive idle airflow settings are all stock, so the LTIT's aren't disabled or anything like that.
Any insight here? I'm kind of at a loss. My next plan of attack is to try a Complete Reflash and then upload the calibration again, as I can't really think of anything else to try.
Any insight here? I'm kind of at a loss. My next plan of attack is to try a Complete Reflash and then upload the calibration again, as I can't really think of anything else to try.
07-13-2006, 11:31 AM
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They were considerably negative at first, but they're much closer now after basing the RAF tuning off of them. So from the STIT indicator, RAF SEEMS to be pretty close now.
Idle is very erratic though with considerable surging, and the RAF values are much lower than what I expected. They're even pretty close to the stock range at warm temps, so I can't help but think there's a vacuum leak somewhere... But this has been gone over several times, and no leaks can be found.
This is on a 408 car with a mid 240's duration cam, Fast intake and NW TB.
Idle is very erratic though with considerable surging, and the RAF values are much lower than what I expected. They're even pretty close to the stock range at warm temps, so I can't help but think there's a vacuum leak somewhere... But this has been gone over several times, and no leaks can be found.
This is on a 408 car with a mid 240's duration cam, Fast intake and NW TB.
07-13-2006, 12:33 PM
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To get my friends' cams to idle, I had to reduce the IAC's control over idle once I got it in the ~70 count range at warm idle. I'd try dropping 20~25% out of the three airflow tables. In EFI Live, they're called:
This worked on both 232/234 .595/.598 112 cam'd cars. No more surging at idle.
- Filtered RPM Airflow Correction (B4512) - Adds/Subtracts air based on RPM rate of change.
- Learned Airflow Correction (B4514) - Correction to learned airflow when engine speed is high/low in P/N or D.
- Direct Airflow Correction (B4515) - Correction to direct airflow when engine speed is too high/low in P/N or D with or without A/C.
This worked on both 232/234 .595/.598 112 cam'd cars. No more surging at idle.
07-13-2006, 01:04 PM
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There's values that sound similar to those in the adaptive idle airflow section of HPT, but the problem is that most of them are based off of LTIT's, which on this car aren't reporting like they should. It all kind of compounds together and causes a trainwreck of an idle.