How to get a heads/cam car to idle

[Yelo]

this was originally posted on LS1tuning.com (which in turn was a re-post from LS1Tech.com)

all of this information is assuming the use of LS1Edit.....but since all the information is fairly generic and all you are doing is scaling tables and changing static values it should work 100% fine with HT Tuner. if the tables are not compatible with HP Tuner I would be grateful if someone would be able to adjust the information contained within this post

Without Further adieu........

Originally posted by NoGo on ls1tech.com



Here are some things you can try.



Idle Limiters --> Idle Speed: 950

Idle Limiters --> IAC Park Position: Raise all points from 40C and up to 21

Idle Limiters --> Idle Air In Gear: All points 60C and up to 8.6

Fuel --> Main VE Table: Multiply column 400 rpm by 60. Multiply column 800 by 80. Multiply column 1200 by 90.

Ignition --> High Octane Table: Add 2 deg to all points 400 to 1000 RPM, .08 to .32 g/sec



Once done with this program, start the car and check for surging. If the car surges, unplug the IAC and see if the surging stops. If the surging stops follow below.



Idle Limiters --> Idle Air in Gear --> All points above 60C to 9.2



Take the car for a drive and check your idle. If the car goes on cruise control reduce the Idle Air in Gear Table .2 (further if necessary). If the idle holds at 2000 RPM for extended periods of time reduce the P/N Airflow Decay table for all points above 10 MPH by 5% (multiply by 95) until this stops. Be vary careful on this table.



If car keeps surging with the IAC unplugged two more things to try.

Multiply Main VE table by another 95% (total reduction of 85%). Repeat until the surging goes away, or until the car begins to hesitate when you take off.

High Octane Ignition Table. Reduce timing for all points 400 to 1000 RPM, .08 to .32 g/sec by 2. Repeat, but don't reduce it any more than 6 degrees.





If your car still doesn't idle after this, then you have other problems, and should start looking elsewhere.

[jimmyblue]

I would add that scaling the VE by 0.6, 0.8, 0.9 in one
straight shot might well take you past the sweet spot,
that being the true VE of the motor. The amount you
need will depend on how radical the cam, etc.

I think you'd be better off approaching it incrementally
(say, scale by 0.9, 0.9, 0.9 first, try it out, scale again
by 0.9, 0.9, 1.0, try it out, scale by 0.9, 1.0, 1.0...
and maybe even interpolate to try and get it really
tight at the end. Since the idle should be between
the 400 and 800 points, both of them matter and the
slope between them should match the true VE falloff
with decreasing RPM.

On the other hand if you just make it fat maybe the idle
response to IAC will get so soggy that the loop gets
stable again....

The cut-and-try is more of a pain when you're dealing
with cold idle. I know SloppyRob had played with
this earlier and it took a bunch of fiddling to tune in
nice. Maybe he has some good final settings by this
point and can tell us what kind of cam/exhaust it's for.

[Yelo]

Sure....this is only a starting point, and it may well be "too much" but the car will at least idle well enough to be able to fine tune it from there

[rgvsierra]

jimmyblue,

how long would you suggest running the car (in miles) around with those values scaled so if it dosent work to try again...

thanks