carbon on plugs

[ESL]

I have a 92 LT1 was missing pretty bad...especially under a load...put fuel injector cleaner in, changed air filter, gas filter, and finally plugs. Plugs on left side were fine...normal burn. BUT all 4 plugs on right side were heavy carbon black...What controls spark to each side of engine? or any other ideas ?

 

[Hib Halverson]

Is the service engine light on?

Is this engine modified?

How many miles on the engine since the last time plug wires were changed?

Have you run the fuel pressure tests listed in the factory service manaual? If so, what were the results?

What kind of spark plugs did you use?

 

[ESL]

Service light would come on occasionally...for a minute then go off...I do not have a code reader...and would always disconnect my battery after a drive. Since doing changes have not had service engine light on...runs fine...but I am sure it is just until plugs get fouled up again.
I imagine plug wires are original. Look ok...if looks count
Engine is not modified...62000miles
AC plugs
No I did not do fuel test

With any of these wouldn't that affect both sides of the engine? It would seem to me something specific to the right side of the engine...but I could be wrong...

Thanks for helping

 

[cntrhub]

Have you attempted to torque the intake manifold bolts on the problem side? You described....''BUT all 4 plugs on right side were heavy carbon black..." Is this "fuel" black, or oil build-up "carbon" black? It's hard to discount an oil fouling problem here, being that the whole bank is fouling? If the intake manifold bolts were all lose, you could factor it to... oil being sucked into the intake ports via intake manifold gasket failure. Without looking at the plugs, I have no idea if it is fuel, or oil yet?
Describe if by grazing your finger across the porcelain of the plug, you feel a powder effect (fuel) or a sticky, hard to clean your finger (oil) effect?
I would try for a leakdown test on the problem bank for a head gasket failure also?
No offense Sherry, but... I believe your statement is misleading or more in line with a fallacy: "dont run it too hard for a few hundred miles until the plugs have seeted and are firing normally." Once a plug is torqued to specs, there is no "seat time." Once the engine is lit, there is no plug I know of that needs a break-in? If anything, it begins to deteriorate from brand new. Race engines are run into the ground with fresh spark plugs. The engines are running at peak performance at the drop of the flag. Again, no offense. We are all here to learn and try to give our most accurate information.

 

[switch]

Does yours have one oxygen for each side like the later C4's?
If so it could be bad or being given the wrong information due to an exhaust leak.
My 95 shows quite a split between the two sides if there is a small leak when I monitor it with data logging software.
Sometimes the one way valves that go to the AIR pump can cause an offset if they go bad.

 

[vader86]

Dont you have an O2 sensor on each side in 92?

That would indicate to me that the O2 on that side was going out.

 

[pthoma1]

Does the PCM correct for each bank (head) I thought that the 2 o2 sensors were just averaged together. But I could very well be wrong. Can anyone enlighten me on that subject, also on a not so realted topic, what year did the LT1 go from bank firing to SFI, and also is there any visible differences in the fuel rails, or anything else to that mater?

Sorry I can't be anyhelp to your problem, everything that comes to mind has already been said, looks like you got somework cut out for you, beter gab a six pack!! Mabey an 18 pack, there are lots of vac. lines to look at!

Paul

 

[Hib Halverson]

Dont you have an O2 sensor on each side in 92?

That would indicate to me that the O2 on that side was going out.

92s have O2Ses on both sides. A lot of carbon on the plugs is not conclusive proof that an O2 sensor is going out though it is evidence that points that way. Do not replace O2Ses only on that basis. I'd only replace an 02 if the diagnostic procedure eventually instructed you to do so.

First thing to start doing is stop disconnecting the battery after each drive in the car. Each time you do that, you're erasing the ECM memory. You lose DTC information along with forcing the ECM to relearn fuel and spark trends. Get a smart batter charger if you are worried about battery discharge.

If the plugs are carbon fouled and you're seeing the engine light come on, I'd first find out what DTC is in the ECM memory. If you don't do that, this becomes just a guessing game.

 

[Mad-Mic]

has it done this for long? when was the last tune up? did the plugs on that side look the same? any blue smoke on startup and then clear up after a few minutes or a few good revs?

i'm thinking maybe the valve guides might be leaking oil on that head.

good luck hope you find it!