Sparks:one Bank Ok One Bank Black!

[MiLexus]

Black sparks on only one cillinder bank?

What can cause this? the sparks on the other side look great. can it be some moran put the timing belt in and missed one or two tooths? or can it be the oxigen sensors on only one side are gone? Lately the car has some very strange cold start problems. When cold it stutters and I hear some small explosions when I push the pedal down. Its not revving up then. can this be related?? When warm it feels OK but then I just miss some power. Let me know if anyone recognizes this! Thanx again!

Cheers!!

[ManicMark]

Hi sounds like you may have one distributor cap/ rotor arm or coil gone down check the rotor arm first then the cap then the coil. good luck

[MiLexus]

Black sparks on only one cillinder bank?

What can cause this? the sparks on the other side look great. can it be some moran put the timing belt in and missed one or two tooths? or can it be the oxigen sensors on only one side are gone? Lately the car has some very strange cold start problems. When cold it stutters and I hear some small explosions when I push the pedal down. Its not revving up then. can this be related?? When warm it feels OK but then I just miss some power. Let me know if anyone recognizes this! Thanx again!

Cheers!!

I checked the belt alignment. looks good. So no morans putting the belt back in the wrong way.

Ignition should not be the problem. Misfire cause nothing but unburned fuel to clean the combustion chamber. (as far as I know)

The problem can not be the ignition as the rotors are dooing 2 sparks of each bank. If it was the ignition I would have had 2 black and 2 clean sparks in every bank. This is not the case. the complete right bank is dirty and black. The left one is clean.

Can it be the EGR pipe or valve? or maybe the ECU that is opening the egr valve too often? this can also explain why the inlets are so black and dirty.

If the EGR valve is causing this.. Why it it only one side? The EGR valve opening is in the chamber of the inlets of both banks right?

Normally Black sparks point out the car is running too rich. Again I wonder: Why only one bank???? How can one bank run too rich and the other OK? How does the ECU calculate the amount of fuel that should be sprayed in?? Can it be the heads are different? Maybe someone put a different older or newer head on one bank?? Should in that case the inlet be fitting the right way? WhyWhyWhy!

Maybe it's just something simple that is causing this. i have too many theories. Is there anyone who has some other theory just let me know!

Thanx for the input.

Cheers.

[ROYT]

You could try swapping the coils over to see if the fault changes to the other bank, if it doesn't I would think that means the coils are OK, and you can look elsewhere.....

[Spinakerr]

Is it the right hand bank (when facing the car)? Could it be the PCV valve is completely blocked with gunk and not allowing correct exhaust of combustion by product?