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View Full Version : Need help setting idle on ls3


Kqrouth
January 27th, 2011, 04:41 PM
I have an 2001 extended cab gmc with a high output ls3. I have a truck intake and 92 mm throttle body and I need help finding a tune because on a cold start it will die over and over. I think the throttle body isn't giving enough air on idle but if anybody has a good solution please let me know and thanks.
joecar
January 28th, 2011, 04:34 AM
Hi Kqrouth,

Do you have the ECM that came with the LS3...?

This thread may help: http://forum.efilive.com/showthread.php?9740-E38-idle-tuning
Kqrouth
February 2nd, 2011, 04:38 PM
No I'm running a ls1 ECM, could that be a problem??
WeathermanShawn
February 2nd, 2011, 05:37 PM
If you have not read through the LS1 Idle Tutorial this might be a good time to do it..http://forum.efilive.com/showthread.php?14439-Idle-Tips-amp-Tricks

I don't have a lot of advice on differing TB sizes, but you might find some hints in the Tutorial or Thread.

Check it out..
Kqrouth
February 3rd, 2011, 12:23 PM
Alright I'll look I to that. And we are about to put a dyno in our shop could that help with making the overall tuning easier?
WeathermanShawn
February 3rd, 2011, 02:18 PM
Alright I'll look I to that. And we are about to put a dyno in our shop could that help with making the overall tuning easier?

Absolutely!
5.7ute
February 3rd, 2011, 04:35 PM
Electronic or cable TB?
Using the earlier pcm will not be an issue as long as the necessary hardware changes have been made.(either the convertor box or reluctor etc)
eficalibrator
February 4th, 2011, 02:59 AM
First things first... Do you have good air-fuel ratio control? The LS3 is VERY intolerant of lean conditions at idle and will misfire significantly with as little as 5% lean of stoich. Poor AFR control would be a symptom of either improper injector characterization or airflow mapping.
Kqrouth
February 4th, 2011, 12:39 PM
Okay good cause I've just started with the tune and I've heard that the idle is the hardest thing to get right so mabe after that it will be easier.
Kqrouth
February 4th, 2011, 12:40 PM
Cable TB and yes I've made all the changes.
Kqrouth
February 4th, 2011, 12:43 PM
No I it runs lean I'm working on that. But I've mostly just been working on the idle and havnt paid much attention to the air/fuel ratio. Also I just bought a new MAF sensor.
slows10
February 4th, 2011, 01:22 PM
I think eficalibrator was saying attention is needed with the idle air/fuel ratio. Need to know what it idles at. Was the Maf sensor faulty?