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Discussion Starter · #1 ·
I will have Jeremy double check this when he is here BUT I think what I found was the problem and the problem's fix.

The PROBLEM: the car started to idle rough, with something like a miss at idle and some off idle roughness; didn't feel like spark it felt like air/fuel. The hotter it was out the worse the problem was too. Just an almost dead miss at idle but definitely not spark and again the same coming off of idle. Once over about 1000 rpm it seemed fine. Coming off idle when you felt it the effect was very disconcerting too.

First attempt at a fix here in small town PA where they have ONE 'known refinery' gas station was to add a bottle of Red Line SI#1 fuel treatment. It used to be called injector and valve cleaner; it is one of two things they make that is worth a damn. **Jeremy's dad told me about this stuff about 15 years ago** I put the bottle in and ran the tank down about 12 gallons - same problem. Hmm, maybe it's a touch of water. Hunted up some 99.9% isopropyl alcohol and added it - same problem.
Pulled off the Vararam and cleaned off the throttle plate and the orifice well with CRC contact cleaner: and it 'helped' a bit but still the problem remained.
NOTE: IF YOU EVER SPRAY 'BRAKE CLEANER' IN THE THROTTLE BODY AND START IT BE CAREFUL AS YOU HAVE JUST MADE THE INFAMOUS 'MUSTARD GAS' - IT WILL ACT LIKE A SUPER VACUUM IN YOUR LUNGS! The exhaust will be pure white too.


Today I changed the air cleaner in the Vararam and re-cleaned the T- body blade and orifice. As you know, the LS2/3/6 all have that flimsy fuel rail and coil pack cover; just a POS. When you put your hand on it most of the time it will move and tilt. And it did today.

The FIX: well, so far: I decided to push down on the injectors under the fuel rail and one of them just sort of 'clicked' down just enough to be felt. I think the O ring was not fully sealing in the intake manifold, I checked the rest of them and all were OK. Started it and it has been idling for about 5 minutes like new.

I think the cause is when we are messing around under the hood we accidentally jar or move an injector via pressure on the fuel rail just enough to move the O ring's seal and we get an air fuel anomaly in that one cylinder and we feel it at idle and off idle. Seems to run fine and won't set a code either.

I still intend to have Jeremy data log the thing and look at it but, for now, it seems to be fixed. Just thought you all would like to know.

olddog
 

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Discussion Starter · #2 ·
Seems I was wrong - while much better the slight off idle miss is still there BUT the idle is much better.

Why this just happened after 23 thousand miles is an enigma to me.

Where is Maven when I need him? :lookinup:

olddog
 

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I hate ignition problems. Keep us posted:thumbsup:
 

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Discussion Starter · #4 ·
Midnight,

All I know at this point is it's on the left bank for sure. So, I am down to one of four but it is definitely A/F and not electrical as far as the coil pack or spark is concerned.

With NO GM dealer of any kind in Hanover, PA anymore it will be interesting. Will have to drive to York or Gettysburg and 'hope' someone there is competent with the scan tool.

My $$ says it's an injector not closing correctly.

Good hearin' from you.

'dog
 
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