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Discussion Starter · #1 ·
I recently installed an LS1 TB and LS6 MAF on my L67. I am really pleased with the throttle response and performance of the LS1 TB except for when I first start the car after it's been sitting overnight. During the first few minutes after starting the car the idle varies widely from 400 - 1000 rpms. Sometimes it gets so low I have to tap the throttle to keep it from stalling. Once the car warms up it runs and idles great. Anyone have any tips for improving the cold start idle? Or is this just the reality of having a Stage 2 cam and LS1 TB? I have an ICCU that I am using to dial in the STFT to be +/- 2%. My low ICCU MAF setting is 95%. I am running 42.5 lb/hr injectors.

Thanks,

Rich
Austin, TX
 

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Did you redrill the hole in the tb blades? zzp epoxies them up. A local guy did this and it seems to have helped his. He also replaced his MAF at the same time. There was also a post on club GP about the ICCU having some cold start issues so your problems could be there.
 

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If you drill the epoxied throttle blade out again and take a dremel and enlarge the IAC slit that ZZP made too small at the back of the throttle body, it really makes a world of difference!



There's an LS1 install guide that Zooomer posted on the LS1 product page. Brent and I added many tips and suggestions for things like this, if there's a problem with the kit I've had it and the fixes are in there, its worth a read for every ZZP LS1 owner. HTH!
 

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Discussion Starter · #5 ·
Thanks for the tips

Based on your replies it appears I need to

1. Drill out the epoxy on the TB plate
2. Open up the IAC slit more
3. Increase timing on start up

I will give these a try.

Thanks,

Rich
 

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Let us know what happens. Mine is starting to do this now that its getting colder. I also have the hole drilled out on the blade.

Scott
 

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Rich,

I drilled out the epoxied hole in the butterfly but didn't modify the IAC slit at all. There wasn't much difference. What you have is the result of the S2 cam. I had to have my idle raised slightly and now it doesn't fluctuate even 150 rpm. It still feels like a cam, though. :)
 

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My '98 GS idled badly when I started it in the cold. All I did was dial in a bit more fuel at idle from the AFC2 and all is well.
 

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I have alot of the same idle fluctuations with a MP112 and a stock TB(for now) This is and has been a real concern for me cause the idle is quite unpredictable..More so with the onset of the colder weather now. Violent surges ect...

Im thinking its cause of the aftermarket cams(TEP in my case) IAC and The mini A/F....While I havent narrowed it down yet I think and hopeing that some HP tunning will really help..The A/Fs seem to be a good short term solution but Hp is the "right way"....to go that is...

Has anyone noticed and strange idle drops anfter a run...On decelleration. Idle drops some and hovers around 1500-2000rps the drops off to idleor about a grand....Doesnt feel like a downshift..I was wondering if it could be due to a mini A/F...I heard that they can have an efect on the shifting quality of the trans in some circumstances.
 

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My idle doesnt really fluctuate that much but you can tell it does a little bit and my lights dim and my volts gauge goes from high 14 down to 12 volts. As soon as it warms up it goes away. Anyone elses lights dim?

Scott
 

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Rich,

Like some have said, I believe this is not a problem with the TB blade or the IAC, although these can sometimes help as a side-effect. I believe that the problem is caused by aggressive cams throwing off the startup fuel table, namely the Startup AFR Correction vs ECT tables. I'm pretty sure that the right way to fix this is by making the startup AFR a little less rich. I have a bigger cam than most people, the INTENSE nitrous blower cam, and this has been a bigger problem for me since the weather started cooling off. I'm still racing however, so this is taking a lower priority for me as some tuning and trial and error will be required to get it right. I'll probably post about it when I get to it.

John
 
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