Cold start issue
Thread Starter
Teching In
Joined: Nov 2017
Posts: 7
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Cold start issue trying to narrow down a cold start problem. The car was tuned for warm start with iac counts around 40-45 and idling around 875. It will not idle on a cold start unless you keep your foot on the gas. Even then there is an extremely loud howling noise coming from the iac until it's warm. In order to get it to cold start we had to crack the to blade a little now causing hanging idle and "cruise control " while driving. Im thinking the only possibility is the iac passage on the warr 92 tb not allowing enough air in or any at all. We tested this by removing the iac from
the tb and it still would not start. But if we removed the line on the intake from the pcv it would fire right up. Is there anything I'm missing here?
the tb and it still would not start. But if we removed the line on the intake from the pcv it would fire right up. Is there anything I'm missing here?
Launching!
Joined: Jan 2018
Posts: 283
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LS1 VS base 2 bar.hptim assuming this is cable throttle?
im certainly not full bottle on idle tuning or setting up a perfect idle data log.
however in my experience I find that cable throttle with decent cam require the following which is sort of a rob peter to pay paul. I usually set a cold idle of 1000rpm or 1050rpm and get it to maintain that idle with about 20degrees timing. I thing use the idle base and ECT compensators so that I can reduce warm idle to 850/900 by running about 5 degrees. I then use the idle base tables to throw timing in if rpm dips as well as the normal idle spark compensators.
the IAC can only add as much air as it can flow.
cathedral heads in my opinion will not idle correctly if they are lean or super rich. get your fuel right first and I find my timing trick works. you can also remove large amounts of timing from the 0.12/0.16/.20 area around 1200-2000rpm. this will help it return to idle on coast down without rev hang.
ill probably be ridiculed but I use timing to cheat for idle tuning as there is only so much air the IAC can add or hold off.
I also delete rolling idle and only use cracker and follower strategy.
I also find a 3-5mm hole in the blade saves so many head aches. a large camshaft requires more air. the hole gives it the air it needs to maintain stable idle and return to idle
post your file
here is a base file for a manual LS1 2Bar single turbo the went on the make 920rwhp on E85 on SBE LS3
im certainly not full bottle on idle tuning or setting up a perfect idle data log.
however in my experience I find that cable throttle with decent cam require the following which is sort of a rob peter to pay paul. I usually set a cold idle of 1000rpm or 1050rpm and get it to maintain that idle with about 20degrees timing. I thing use the idle base and ECT compensators so that I can reduce warm idle to 850/900 by running about 5 degrees. I then use the idle base tables to throw timing in if rpm dips as well as the normal idle spark compensators.
the IAC can only add as much air as it can flow.
cathedral heads in my opinion will not idle correctly if they are lean or super rich. get your fuel right first and I find my timing trick works. you can also remove large amounts of timing from the 0.12/0.16/.20 area around 1200-2000rpm. this will help it return to idle on coast down without rev hang.
ill probably be ridiculed but I use timing to cheat for idle tuning as there is only so much air the IAC can add or hold off.
I also delete rolling idle and only use cracker and follower strategy.
I also find a 3-5mm hole in the blade saves so many head aches. a large camshaft requires more air. the hole gives it the air it needs to maintain stable idle and return to idle
post your file
here is a base file for a manual LS1 2Bar single turbo the went on the make 920rwhp on E85 on SBE LS3
Thread Starter
Teching In
Joined: Nov 2017
Posts: 7
Likes: 0
Thank you for all the info. We ended up switching out the warr92 for a nw92 and it seems to have corrected the problem as far as cold start. For some reason the iac on the warr wasn't allowing any air to flow whatsoever and now we are getting the tune right with the nw92. Now the only problem it's having is that if I stab the throttle while in reverse it will die as it can't catch itself on the way down and hold idle. I don't have the logs with me but if we don't get it corrected I'll get them and post them. Everything was a bit out of whack from trying to get the old tb to idle.
