My LT1 problem is where I would be in 4th gear (A4) and give it some gas the motor would ping and backfire at around 2000 rpm. It would Idle fine and would get up and go in the higher rpm range but as soon as I get near the 2k mark that where my problem is.


I replace "all" sensors, replace the plugs wires and spark plugs, opti is not that old, coil pack is MSD. These parts dont even have 5k on them yet. The gas is new. Tested the injectors and they passed.

My car ran fine last summer and I stored it during the winter but I started it up twice a month with no problem.

Open loop it runs fine but when it hits Closed loop that where the problems begins.

Any ideas? I'm leaning towards valvetrain issuses....

Thanks!

 

If you can hear "pinging" you have a major problem. The PCM (with stock tuning) can pull up to 15-degrees of advance to eliminate it. Normally you won't even hear it. Are you using premium fuel? Is it running hot? Is there a possibility of severe carbon buildup in the combustion chambers? Did the tune lower the upper limit on knock retard to the point where it can't protect your engine?

 

I found carbon build up on #7 plug, I run on premium, I dont know if the tune lowered or raised anything.

 

I don't mean a bit of carbon on the plugs... I mean hard carbon deposits in the heads, large enough to raise the compression ratio.

 

That I do not know. I'm going to try some seafoam and if that doesnt work I'll try some Lucas in my oil to see maybe a lifter is stick or such.

 

find out what was done in the tune.......

I bet he added alot of timing and limited the retard....... If you hear it ping you really have a big problem somewhere.

 

Yeah I guess I'll try and do that and see what he says.

 

This is what my tuner stated to me in a email starting with my first e-mail I sent him.

----- Original Message -----
From: whitethunderz28@aol.com
To: ion@madtuner.com
Sent: Saturday, April 19, 2008 11:32 PM
Subject: Requesting tuning information "Past Customer"

HI,

My name is Josh xxxxx and I bought the E-mail tune from you a few years ago for my 94 Z28.
I was wondering if you can give me the information of the tune that you gave me like timing/ retarding, etc.

Just wanting to know because my car is pinging/ misfiring and I'd like to make sure that it has nothing to do with the tune.

Your help is appreciated.

Thank You,

Josh

-----------------------------------------------
From: Ion Soltan <ion@madtuner.com
To: whitethunderz28@aol.com
Cc:Bccate:Sat, 19 Apr 2008 11:42 pm
Re: Requesting tuning information "Past Customer"

Hello Josh,

my tune will not cause any of these issues as the timing used is safe. Besides, the tuning does not change. If your car was working fine before, the tune was fine. Something else is wrong.

 

I just dont understand why wont he give me the information so I could have something to work with?

 

well was it working fine before?

check some of the things injuneer said......I would guess you probly don't have much carbon build up unless you put around like a little old lady.

You have any vac leaks? possibly bad gas?, maybe some water in it?

 

I dropped in a new 255 FP in it last summer, threw some heat in there when I stored it.
I changed my mind with using SeaFoam cause I killed a couple of o2s with that stuff.

I think I might just look around for a newer enging since this one has 178k on it already and all internal are original.

 

If it just started I would think it has to be the fuel.......

Try some octane booster or water remover and see what it does.

If the engine is running fine then another one is going to do the same thing if you swap it. does not sound like an engine problem to me......It could be, what are your driving habits?