Hey guys,
I installed a cam over the weekend (232/234, 110 LSA) and im having dramas getting it to start and hold idle. Its a 5.7 LS1 conversion (Manual)
The tune base (ive tried a bunch of tweaks relating to spark,air and fuel also) is speed density (MAF fail at 0Hz), LTFT disabled, forced open loop. I did some driving with it before the cam swap and it was great.
Steps taken for the cam tune:
Timing bumped up (High octane, low octane, in drive, in park) to low 20s
RAF increased across the board (by 3g/sec)
Start up air flow initial increased (by 2-3 g/sec)
Base idle at 850rpm
It wont start without giving it some throttle and then will not idle without throttle. When trying to start the IAC is at 310 steps, so unless im missing something, I cant add more air. When warm the IAC counts are at 40.
The only way I have had it idle:
1) Keep it alive on the throttle
2) While giving it throttle, set the IAC to 0 using special controls
3) Turn off IAC control override and let it do its thing
It then revs up over the idle setting and then comes back down and idles like a dream (The IAC counts then come dwn below where they were when it was tryinig to die all the time)
Im not sure what im missing..... What stumps me is why the IAC can control the idle if I manually "reset" it using the special functions and why I can get it to start without a bunch of throttle.
The log file shows it no starting, then starting with throttle, and then idleing ok after I do the IAC set to 0 then off again (You can see in the log where the IAC commanded and position goes to 0 then back up, right before the revs climb and then settles on a decent idle speed). The tune file is the tune used from that log.
Ive followed the LS1 cam install base tune instructions ive found plus tried a bunch of different things to try and increase air flow at start up. The log will show the fueling is a little off, but I havent really had it running enough to nail it down.
I appreciate the help up front!
9.39 Throttle start then idle IAC.hpl Channels CAM.Channels.xml L277904 V9.39 VE & RAF & Start Up Air.hpt Wideband AFR.MathParameter.xml