LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Stubling start?

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Old Apr 13, 2009 | 07:43 PM
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Default Stubling start?

I've had a small problem lately where it will take a bit longer to start occasionally. Also - when it starts, it will stumble its way up to 800 rpm. Sometimes it will start up, shoot to 1500 then come back down to idle. It drives fine and pulls hard, though.

Also - It is running a bit rich.

Any ideas?
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Old Apr 13, 2009 | 07:58 PM
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Originally Posted by nik1703
I've had a small problem lately where it will take a bit longer to start occasionally. Also - when it starts, it will stumble its way up to 800 rpm. Sometimes it will start up, shoot to 1500 then come back down to idle. It drives fine and pulls hard, though.

Also - It is running a bit rich.

Any ideas?
What's your fuel pressure doing while you are having these symptoms?
I'd also clean your IAC.
You could also perform the ICM cooling mod.
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Old Apr 14, 2009 | 07:41 PM
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Originally Posted by ss.slp.ls1
What's your fuel pressure doing while you are having these symptoms?
I'd also clean your IAC.
You could also perform the ICM cooling mod.
what is the ICM cooling mod? (I searched.)

Not sure about the fuel pressure.
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Old Apr 15, 2009 | 03:23 AM
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Originally Posted by nik1703
what is the ICM cooling mod? (I searched.)

Not sure about the fuel pressure.
http://shbox.com/1/4th_gen_tech2.html#ICM_cooling
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Old Apr 15, 2009 | 01:32 PM
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Originally Posted by ss.slp.ls1
Neat idea, although this issue does not seem to be heat related as it happens on cold starts as well. You are leaning towards fuel pressure? Would a fuel pressure issue also cause running rich?
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Old Apr 15, 2009 | 01:33 PM
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Originally Posted by nik1703
Neat idea, although this issue does not seem to be heat related as it happens on cold starts as well. You are leaning towards fuel pressure? Would a fuel pressure issue also cause running rich?
Never hurts to test fuel pressure. Go borrow a gauge from autozone.
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Old Apr 15, 2009 | 01:57 PM
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Originally Posted by ss.slp.ls1
Never hurts to test fuel pressure. Go borrow a gauge from autozone.
will report back later today
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Old Apr 15, 2009 | 02:38 PM
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Do you have some form of cold air induction? If so, I would take off your intake tubes and clean them as well as the throttle body. Most idle issues and long starts are because too much carbon has built up on these parts.

I cleaned and oiled by KandN Filter, cleaned the intake and MAF with brake clean, and cleaned the throttle body with throttle body cleaner about 5,000 miles ago and my car starts right up. I could def. tell a difference in starting after I did this.
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Old Apr 15, 2009 | 03:33 PM
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Originally Posted by camerory
Do you have some form of cold air induction? If so, I would take off your intake tubes and clean them as well as the throttle body. Most idle issues and long starts are because too much carbon has built up on these parts.

I cleaned and oiled by KandN Filter, cleaned the intake and MAF with brake clean, and cleaned the throttle body with throttle body cleaner about 5,000 miles ago and my car starts right up. I could def. tell a difference in starting after I did this.
I have a ramair hood w/ram air intake and a K&N filter, which was cleaned and oiled not long ago. also my car is a 93' so i don't have a MAF. i could clean the TB, it has got stuck open on two occasions. although i don't have a bad idle, there are just sometimes where it stumbles up to idle, or shoots way past it and then goes back down.
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