bboeckin

I really need help here. My car has been running really rough for the past few weeks and I have been trying different things to try and figure out what the problem is. Here is a list of what I have done and seen.

First, when I pull the spark plugs, the electrode is very white almost to the point that it is green and the base of the threads just on the inside of the combustion chamber are coated with carbon. I have changed spark plugs and o2 sensors to solve the problem with no change. All spark plugs look the same!!

Second, I don't think that I have a vacuum leak at the present moment, but I know that I had one before around the PCV line on the rear driver's side valve cover and another one around the EGR when it attaches to the intake. Those have both been fixed and didn't have an impact on the rough ride or the white spark plugs.

I have done a compression test on all eight cylinders and got a very consistent 215psi on each cylinder.

I don't know how significant this is, but ever since the car has been running rough, I have been hearing significantly more valve train noise (at least I think that it is valve train noise).

The car generally exhibits large amounts of KR in 6th gear under approximately 30% load (4-9 degrees). I don't know why.

I made some ATAP runs last night and can be seen at ftp.ni.com/incoming/99Z28.zip. Nothing really big to see other than around 4800 RPM, it goes really lean (~.79mV) for some reason.

I really need help in troubleshooting this!! I have stage 2 ARE heads, FLP headers and y-pipe, LS6 intake, ported TB, and MAF ends to name the most important stuff. It is late and I am sure that I missed something.

At this point, my guesses are related to fuel system (fuel pump, regulator, etc) since it effecting each cylinder similarly.

Any help is appreciated!!

bboeckin

ttt

CHRISPY

White plugs indicate coolant in the combustion chamber (ala blown head gasket or cracked head or block)
Are you running boost or NO2?
Is your oil looking milky or oil getting in your coolant?
Cheers,
Chris

bboeckin

I haven't run N2O or any forced induction setup. I haven't noticed any coolant loss or coolant in the exhaust pipes. Nor have I noticed the white exhaust cloud that usually accompanies burning coolant. Both coolant and oil look good. Thanks for the suggestions.

bboeckin

When the car ran normally, the plugs were clean with a slight brownish tint. They have only recently gone white. They also seem to be oxidized or pitted just a little bit on the electrode. I will go ahead and change the fuel filter and check the pushrods.

There is no doubt that I am getting some detonation. I can hear it! Furthermore, when I look at the logged data, the pinging seems to correspond to low o2 readings. However, for audible pinging, it doesn't seem to be retarding the timing much (~4.5 degrees max). The LTFT's are around 10% for each bank without the MAFT. I have a MAFT will knock the LTFT's down close to zero but it doesn't seem to have a positive or negative effect when it is connected. In fact, I took the MAFT out of the loop to see if it was causing the problem.

Please check out the logged data. It may tell you something that I haven't noticed. Also there has been a noticible loss in power.

blackhawk2000

KR in 6th is normal under load. don't worry about it. Lose the MAF ends, and see how it runs.

steve

may i suggst this.
replace the fuel filter.
try the car out and see what she does. if it still act up, pull each valve cover and check each pushrod.

the plugs sound normal to me, i see em in these cars like that all the time, slight greenish tint and all....

steve frank

Pro Stock John

iTrader: (34)

What are your ltrims?

You might be a bit lean and getting some detonation. If so I would get a MAF T or remove the ported MAF ends.

bboeckin

Another interesting note is that from ATAP runs, I am noticing the car is running about 5-7 degrees hotter than it was with the same ambient temperature.

cablebandit

iTrader: (37)

Sounds like its lean to me. Do some atap runs in drive or 4th gear and see what your o2s show. They dont respond quickly enuff to try and read in 1-2-3 (m6)

don

definetely sounds lean,check fuel pressure,if normal,return the induction back to normal[may be just too much air]

Red 99 TX SS

I was also getting a lot of knock retard until I had intake and valve cleaner run through my car. Jayson at MTI thought carbon buildup on my car was the cause of the detonation. I went to Meineke Muffler and had the Valvoline intake cleaner run throug my car. You will see black smoke out the exhaust as a sign that the carbon buildup is being cleaned. Since then I have no pinging at all.

Mt Ltrims and O2's were perfect as was my total timing when I was pinging. Maybe this will help you as well.