sick01ws6transam

iTrader: (2)

I have a tsp 408 that I just put a new set of cnc'd ls3 heads and Intake on, and now I am getting a misfire on cylinder 6.

I have done the following
1) change plugs
2) change wires
3) change coils
4) changed injectors
5) Spark plug tester and is showing fire
7) Compression test 180 on cylinder 8,6,4, and 2
8) rocker arms are tight and working very well
9) I looked for broke valve springs( all are new and in good shape)

The plug is dry but carbon fouled!! any help would be great!!!!!!!!!

cyipher

iTrader: (1)

Cpk re-learn?

joecar

How did you determine it was #6...? Is that the only plug that is carbon fouled...?

Have you tried moving that injector to a different cylinder...? Have you moved the coil to a different cylinder...?

sick01ws6transam

iTrader: (2)

tech 2 shows misfire counts and cylinder 6 just goes off the graph.

Old Geezer

iTrader: (3)

Gasket slipped out when the intake was installed?

sick01ws6transam

iTrader: (2)

I will check today. Thanks for the helpful hint!

wait4me

iTrader: (10)

Does it only missfire at idle? or does it do it at say 2500rpms.

Also, did you check for correct push rod length? The heads could be shorter deck.

Also, i agree with Joecar, move the fuel injectors around if you see something odd also. If it follows, then just replace the bad injector.

sick01ws6transam

iTrader: (2)

I have already ruled out injectors. I have already replaced them along with the coils.

joecar

What if one of the replacement injectors is bad...?


The plug is getting carbon fouled because that cylinder is burning overly rich... a leaky injector can cause this, and so can insufficient air (is intake and/or exhaust valve opening all the way...?).

sick01ws6transam

iTrader: (2)

I will double check to see if the valves are opeing all the way. Thanks for another great hint.

BLK02WS6

iTrader: (2)

After everything else you did, it sounds like a pushrod/valve issue...

jimmyblue

iTrader: (11)

Have you used a "noid light" or a voltmeter to see that the
injector is being fired electrically? Look for differences from
adjacent cylinders. Measure volts from BAT to the low side
of the injector for better resolution.

Now I have heard, but can't confirm, that misfires sometimes
show up on the next cylinder in the firing pattern, from where
the action really is. But if #6 plug condition is different than
the bank-neighbors, that's probably saying that you've got
the right hole.

I don't think soot necessarily says rich. It could be a lean
misfire. Either way you get elevated HC. I think to get a
rich misfire you'd have to be mighty damp, and there are
not that many failure modes that will cause excess pulse
width or stuck-on. Still reading the voltage (as proxy for
PW) will tell you if the #6 is getting treated any differently.

Now given that this is a new top end, I would not rule out
a bad vacuum leak at the intake manifold, at that runner.
This could be checked with propane while watching the
misfire counts in real time. I have one of those weed
burner torches which without the "hat" will reach in real
nice, but about any unlit torch would probably do.

sick01ws6transam

iTrader: (2)

I pulled the intake and the intake valve for number 6 was white. The rest of the intake valves were wet and darker looking. I have ordered two new valves, one intake and one exhaust. The new parts will be here weds. I am going to lap in the new valves to make sure they are seating correctly.

flame

iTrader: (13)

White from burning antifreeze?

BlumaroZ28

mannyman84

iTrader: (2)

Has it been tuned?

1ltcap

this is what i was thinking. sounds like the exhaust valve may be hanging closed.

sick01ws6transam

iTrader: (2)

I have put new valves and still have the same problem!!!! I even moved the pushrods and rocker arms to cylinder 2 and still have a problem on cylinder 6!!

sick01ws6transam

iTrader: (2)

Next weekend I am going to pull the cam and put a factory cam in it to see if the cam was mismachined.

sick01ws6transam

iTrader: (2)

anyone?