95 Vette Lt1 idling rough

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Nov 9, 2007 | 03:48 PM

youngrodder

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95 Vette Lt1 idling rough

I have a 95 Vette LT1 motor in my 1948 Chevy truck. I have a Howell engine harness and reprogrammed CPU. Non emission set up. My motor starts up but idles rough.

I have confirmed that my fuel presser is in spec.

Here is what I think are the possible causes.
1 - The motor sat for 7 years. I am thinking that I need to have the injectors cleaned.
2 - I am running open headers. insufficient back pressure.
3 - Opti

Looking for feedback.

Thanks in advance
Marc

Nov 9, 2007 | 03:56 PM

Vicious95Z28

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Injectors or opti maybe. I think you can rule out open headers, that's nonsense. I would even go as far as saying it could be in the tune but we don't have much info to work with here

Nov 9, 2007 | 03:59 PM

youngrodder

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I was also going to run a scan on the motor to see what comes up.
I want to try to rule out as much as possible. I trust the tune but I will send it back if I can rule enough of the variables out myself.

Thanks

Nov 9, 2007 | 04:03 PM

Vicious95Z28

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I love the ol truck BTW

Nov 9, 2007 | 04:07 PM

Rocky70304

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Yeah, injector, or opti are both good posibilities. Is there any tapping, lifters could have bled down in that amount of time and the valves are misadjusted slightly causing it to run rough. just another possibility...

Nov 9, 2007 | 04:13 PM

youngrodder

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Quote:

Originally Posted by Rocky70304

No tapping or knocking. I did notice when I was feeling the heat from the header tubes that some tubes were much hotter then others. This is why I was also thinking it was an injector issue.

Thanks

Nov 10, 2007 | 02:44 AM

sbs

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From: VA

Quote:

Originally Posted by youngrodder

Here is what I think are the possible causes.
1 - The motor sat for 7 years. I am thinking that I need to have the injectors cleaned.
2 - I am running open headers. insufficient back pressure.
3 - Opti

Looking for feedback.

1. Seems pretty likely. Simpler/cheaper to replace than to have cleaned.
2. Unlikely
3. Maybe, if stored in a high humidity environment. If you have easy access to it in that vehicle, pop it open and see what it looks like inside.

Other thoughts:

IAC needs cleaning / adjustment?

You took the MAF off so it's running in SD mode, and the stock SD tables aren't all that well tuned on the 94-95 cars. OTOH my idle isn't rougher in SD mode, so I dunno.

Best place to go for help on this is:
http://www.camaroz28.com/forums/forumdisplay.php?f=9

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Nov 10, 2007 | 10:32 AM

z28hustle

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so the car will naturally go into speed density mode without the MAF? so does that mean its ok to run the 94 and up lt1s without it??

Nov 10, 2007 | 11:49 PM

#10

sbs

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From: VA

Quote:

Originally Posted by youngrodder

Good point I did look into buying new apposed to having them cleaned.

I'd consider picking up a used set of stockers ($25-$50) just to see if it helps.

Quote:

As for the Opti. Do I need to pull the balancer to remove the opti cover? I have not looked at it up close yet.

Yep.

Nov 11, 2007 | 01:03 PM

#11

youngrodder

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Quote:

Originally Posted by sbs

I'd consider picking up a used set of stockers ($25-$50) just to see if it helps.

Yep.

I could try that.

Update:

I did confirm that each injector is receiving a signal to fire with the use of my noid light. I then tried to unhook one injector at a time and it seems to me that only about three injectors are working.

I also tried tapping on the injectors while the motor was running and it seemed to get a little smoother.

Thanks for the feedback
Marc

Nov 11, 2007 | 05:29 PM

#12

emerica4601

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From: king of prussia, pa (home) and williamsport, pa (school)

my vote is that there is condensation in your opti, creating it to run like ****. just let it idle, and give it small revs. 95's should be vented optis, make sure your vent tube is hooked up well to the nipple, and then to the intake tube. injector cleaner would also not be a bad idea since the motor sat for so long.

my theory is that the opti is always the problem, no matter what haha. just let her run for a bit. itll clean up

Nov 16, 2007 | 03:50 PM

#13

youngrodder

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Update!!

It was the injectors that were the culprit. I purchased a used set off eBay and it fixed my rough idle. It sounds and runs sooooo much smoother.

Thanks for everyones feedback.
Marc

Nov 16, 2007 | 07:17 PM

#14

jasonp31

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From: Clover, South Carolina

Hate to change the topic, and I'm glad you got it fixed, but do you happen to have any more pictures of this truck? I apologize if you already posted it somewhere, if you did, can you link it? I would love to see some process pictures, that looks like an awesome project!!

Nov 16, 2007 | 10:04 PM

#15

youngrodder

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Quote:

Originally Posted by jasonp31

Jason-

You didn't miss any pictures, I only posted a few. If you want to see them all visit my photobucket page. Currently the truck is close to 80% assembled as you can see in the outside photos.

http://s79.photobucket.com/albums/j1...uck%20Project/

It has been 7 yrs in the making. I plan on getting it to paint by spring.

Enjoy, and thanks for interest.
Marc