Missing @ Idle - Pros only pls...
Team Owner
Joined: Sep 2001
Posts: 62,178
Likes: 1,740
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: Missing @ Idle - Pros only pls... (Sam Lam)
What you consider a slight miss could be normal for the cam change with a stock chip. Just because CC says you dont have to upgrade the chip, does not make it so.
Racer
Joined: Apr 2003
Posts: 260
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From: Palm Bay Fl
Re: Missing @ Idle - Pros only pls... (vader86)
I agree with Vader...
Just changing to 1.6:1 rockers on my otherwise stock LT-1 seemed to increase the overlap enough to give it what some might consider a 'slight miss'.
-Dave C.
Just changing to 1.6:1 rockers on my otherwise stock LT-1 seemed to increase the overlap enough to give it what some might consider a 'slight miss'.
-Dave C.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
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From: San Diego, Ca
Re: Missing @ Idle - Pros only pls... (autotech)
What difference are you seeing between target RPM and actual? I'd isolate the cylinder with the header method or better yet, disconnect the IAC and O2 and place a piece of 1/4" vacuum hose between the plug wire and cap and then touch the hose with a grounded test light to kill the cylinder and note the RPM drop. When isolated, verify integrity of plug and wire & then check valve height and compare it with all the others and I'd check compression for that cylinder too. Intermittant hard start is probably injectors or fuel circuit, but doubt it's the cause of a miss once it goes closed loop.
Melting Slicks
Joined: Jan 2003
Posts: 2,167
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From: What did the 5 fingers say to the face? SLAP!!
Re: Missing @ Idle - Pros only pls... (autotech)
Gross Valve Lift -
Int. - .488
Ex. - .495
Int. - .488
Ex. - .495
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Melting Slicks
Joined: Jan 2003
Posts: 2,167
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From: What did the 5 fingers say to the face? SLAP!!
Re: Missing @ Idle - Pros only pls... (vader86)
The duration on your stock cam was 202/206. While your new cam is not considered aggressive, I do believe it's too much for the computer to compensate for. My car wouldn't idle until I had a chip burned. You couldn't take your foot off the gas or it would die. Your cam is much closer to my specs than the old stocker, so a slight miss at idle could definitely a symptom. Unfortunately, it's one of those things that you won't know until you try it.
Corvette ***** OG
Joined: Oct 2003
Posts: 4,776
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From: Charlotte NC
St. Jude Donor '05
CI VI Veteran
Re: Missing @ Idle - Pros only pls... (flyersfan1088)
A couple of things, I'd say that is a mild enough cam but regardless of whether it's considered large or small, the duration of the cam in question isn't big enough to cause starting problems. I recently rebuilt my '95 LT1. The cam is a .586 lift (without the 1.6 roller rockers) Duration at .050 is like .248... (and until I pulled the rearend out to regear it, I've been running the stock chip) Point is, there hasn't been a miss occurring.
Sounds to me more like fuel issues. If the voltage isn't set right on the TPS, it doesn't affect starting, does it? I'm assuming it may since if the plate is open too much or too little, the incorrect fuel would be delivered???
Anyway, I just wanted to make the point that I don't think your cam has anything to do with it's starting problem.
Mark
[Modified by C4 Newbie, 6:33 AM 11/7/2003]
Sounds to me more like fuel issues. If the voltage isn't set right on the TPS, it doesn't affect starting, does it? I'm assuming it may since if the plate is open too much or too little, the incorrect fuel would be delivered???
Anyway, I just wanted to make the point that I don't think your cam has anything to do with it's starting problem.
Mark
[Modified by C4 Newbie, 6:33 AM 11/7/2003]
Burning Brakes
Joined: Jul 2002
Posts: 871
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From: Costa Mesa CA
Re: Missing @ Idle - Pros only pls... (autotech)
That's funny (as in strange)
You have the CompCam 08-501-8 cam as do I. It is the mildest cam CompCam makes for our cars. This is what they recommended me at the time when my engine was basically stock. After assembly I had a rough idle (still do) and they said I would have to get an aftermarket EPROM. They recommend it with that cam. You might want to call their tech line again.
So I got an ADS chip. I still have a rough idle but it runs better once it's off-idle. Getting the porting done was what really woke everything up. Now it pulls to 5500 RPM no sweat. But the rough idle still remained.
Then I increased the fuel pressure and that helped the idle more than anything else.
So I am content with my rough idle although I don't think it's missing really. I have a ALDL to PC interface so I can go out with a laptop and actual see what's going on. I suggest that to you maybe.
I am a professional. I'm not a mechanic. But that wasn't one of the criteria's.
BIG JIM
You have the CompCam 08-501-8 cam as do I. It is the mildest cam CompCam makes for our cars. This is what they recommended me at the time when my engine was basically stock. After assembly I had a rough idle (still do) and they said I would have to get an aftermarket EPROM. They recommend it with that cam. You might want to call their tech line again.
So I got an ADS chip. I still have a rough idle but it runs better once it's off-idle. Getting the porting done was what really woke everything up. Now it pulls to 5500 RPM no sweat. But the rough idle still remained.
Then I increased the fuel pressure and that helped the idle more than anything else.
So I am content with my rough idle although I don't think it's missing really. I have a ALDL to PC interface so I can go out with a laptop and actual see what's going on. I suggest that to you maybe.
I am a professional. I'm not a mechanic. But that wasn't one of the criteria's.
BIG JIM
