Spark plug help please?

[Gustyones]

These are the plugs from #4, 5, & 6. It looks like I am running a little lean and I'd really appreciate some direction on how to fix that.

I am also concerned by the tar-like ring on the #6 plug to the far right.

[Steve@Rennsport]

#4 has a color ring, but your picture isn't good enough to determine anything from that without close inspection.

#5 looks too lean.

#6 is using a lot of oil and likely has bad guides.

Hope this helps a little,...

[Gustyones]

Thanks Steve for the quick reply,

Does bad guides mean I am in for a rebuild?

Any advice on how to run 'less lean'?

[stlrj]

Originally Posted by Gustyones

Thanks Steve for the quick reply,

Does bad guides mean I am in for a rebuild?

Any advice on how to run 'less lean'?

Not so fast! Try a new set of ignition wires first.

Hard to believe only one guide wore out while the rest are fine.

[stlrj]

What I am seeing is that your #6 plug has been missing for some time which is why it appears to be fouled so bad. #5 looks perfect as you would expect on any well tuned engine today that runs stoichiometric mixtures regardless of air or water cooled type of engine.

[James Brown]

The do look a little lean and #6 is from oil leakage, but you just can't richen up the mixture or change some jets. You have what you have. Oh i'm sure you could get a custom chip set for your controller (like you did) so concentrating on the leaking valve guide is about all you can do.

[j911brick]

You might want to check cam timing to be sure both sides are equal.

[Steve@Rennsport]

Originally Posted by stlrj

Hard to believe only one guide wore out while the rest are fine.

It happens,....

Cylinder heads run at different temperatures and the guide seals also fail from heat and old age.

Its not that uncommon although I would also be inclined to check the rings on that piston in case they are broken. .

[stlrj]

Steve,

Wouldn't it be prudent to perform the basics first, like an ignition tune before moving into the unthinkable?

Cheers,

Joe

[Gustyones]

Based on the feedback so far I think that in addition to new plugs, i'll also replace the wires, cap and rotor. Could a possible cause be a bad injector? I'd like to exhaust all options before diving too deep into the engine.

[James Brown]

Yes*


* your plugs are the envy of most mechanics around here (except #6) without knowing how many miles are on these plugs and/or the car, to make any rash decisions on the #6 cylinder. For a 26 year old car, I would put the plugs back in! What does the other plugs look like? You can see #6 firing through the oil as the electrode is white so cap/rotor/wires won't do much. In fact, if the other plugs look like the rest, I would just change #6 and drive the car. 26+ years with 1xx,xxx miles on the car means something has to wear out. So doing a leak-down test will check the rings and valves for cracks/warping/leakage. Cracked piston rings and worn valve guides will require the engine to be disassembled. A new plug every 1000 miles is cheaper.

[Bill in OKC]

Originally Posted by Gustyones

Based on the feedback so far I think that in addition to new plugs, i'll also replace the wires, cap and rotor. Could a possible cause be a bad injector? I'd like to exhaust all options before diving too deep into the engine.

Maybe not bad, but a dirty injector?

[Neel]

From what I see, I'd have to agree with Mr. Brown.. If you have an ohm meter, check for high resistance through the plug wire and visually inspect the connections for green stuff (oxidation) Much better than spending $$$ on plug wires, guessing.. My $.02, of course..

[stlrj]

Originally Posted by James Brown

In fact, if the other plugs look like the rest, I would just change #6 and drive the car.

Might just as well change the ignition wire on #6 too.