Cam surge--used search
12-16-2007, 07:47 PM
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Cam surge--used search Ive tried alot of the methods in search like increasing timing in gear and in park. I have LS1 EDIT.
222/222 .566/.566 112 LSA Cam, heads, LS6 intake, MMS Maf.
Idle is fine, driving is fine, fast stops is fine, i have finally gotten all that smoothed out. Its when I come to a stop and shift to park it gets all out of whack.
Any suggestions, maybe I added to much timing? I think i have it set to 35* and higher. Have my idle set at 850 in park and 1000 in gear. I dont have AC.
Thanks
222/222 .566/.566 112 LSA Cam, heads, LS6 intake, MMS Maf.
Idle is fine, driving is fine, fast stops is fine, i have finally gotten all that smoothed out. Its when I come to a stop and shift to park it gets all out of whack.
Any suggestions, maybe I added to much timing? I think i have it set to 35* and higher. Have my idle set at 850 in park and 1000 in gear. I dont have AC.
Thanks
12-16-2007, 09:59 PM
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Too me it just sounds like you need to do some idle tuning. Have you done anything different lately like change a throttle body and/or intake? I'd go to hptuners website, download the RAF tuning configuration and log your PCM using that configuration, then go from there...
12-16-2007, 11:24 PM
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I'm not familiar with LS1edit, but I imagine so. Just read the PCM, make your changes, and upload back into the PCM. There is a write-up either here or on hptuners.com on RAF tuning.
12-16-2007, 11:26 PM
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Oh, as far as the configuration file goes, I'm pretty sure it can't be used with LS1edit. As a matter of fact, some configuration files cannot be used with different versions of hptuners. LOL.
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12-17-2007, 08:43 AM
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An overly rich idle mixture is a prime reason for idle surge, the
motor responds too slowly to air-steps and spark-steps so it
is always late and overcorrecting. Even if the airflow is somewhat
off base it ought to correct eventually (STIT, LTIT) but if it is
surging nonstop that's not the air loop. Fixing the airflow stuff
is good, because it minimizes the perturbation that has to be
taken out to hit idle speed, but the airflow targets are not the
cause of instability, only an initial error.
If your idle MAP is above 40kPa then you are well outside stock
tune for open loop enrichment (cold starts) and probably need
to work over the VE table some, until you see idle O2 sensor
voltages in open loop, hot, start to produce crossings (0.5V)
randomly meaning the mixture is pretty close to stoich. Then
the adaptive spark should be able to keep it pretty tight without
even bothering the IAC.
motor responds too slowly to air-steps and spark-steps so it
is always late and overcorrecting. Even if the airflow is somewhat
off base it ought to correct eventually (STIT, LTIT) but if it is
surging nonstop that's not the air loop. Fixing the airflow stuff
is good, because it minimizes the perturbation that has to be
taken out to hit idle speed, but the airflow targets are not the
cause of instability, only an initial error.
If your idle MAP is above 40kPa then you are well outside stock
tune for open loop enrichment (cold starts) and probably need
to work over the VE table some, until you see idle O2 sensor
voltages in open loop, hot, start to produce crossings (0.5V)
randomly meaning the mixture is pretty close to stoich. Then
the adaptive spark should be able to keep it pretty tight without
even bothering the IAC.
