Reading Spark Plugs ?

[ikle]

The last few years my car hasn't had a smooth idle and when I did a search it was stated that from new they never ran as smooth as today's car because of how the engine was balanced from the factory so I never looked into it any further since the car ran good off throttle to WOT. Now my car has developed a slight ticking sound that is noticeable at 2,200 rpms, like a slight header leak or noisy injectors. So I started to do some poking around and pulled the plugs and they all looked good except for one, which was black, when compared to the rest. I goggled "How to read spark plugs" and it was determined that the plug was Carbon Fouled which was said to do with having a " bad or weak spark"or "really bad compression." I was thinking of seeing if it was spark related first, so after reading several threads, it seems that the way to go is to use a coil pack tester, like the one Kirbans sells, to tester the coil. Then ohm out the spark plug wires and if all that checks out do a compression test. Am I going about this the right way or should I go about it another way. Thanks for your help, Kyle.

 

[John Larkin]

If 5 plugs look good, then its not likely the coil pack. Reason being is the coils are in pairs so you should have at least 2 bad plugs if the coil pack was bad. Ohming the spark plugs sounds good and look at the bad plug closely for a crack in the ceramic. One question though: is the plug black and sooty or black and wet? Also make sure the electrode in the wire is clipping onto the plug properly. Sometimes they can slip off.

 

[ikle]

If 5 plugs look good, then its not likely the coil pack. Reason being is the coils are in pairs so you should have at least 2 bad plugs if the coil pack was bad. Ohming the spark plugs sounds good and look at the bad plug closely for a crack in the ceramic. One question though: is the plug black and sooty or black and wet? Also make sure the electrode in the wire is clipping onto the plug properly. Sometimes they can slip off.

John its black and sooty. Thanks for replying.

 

[Chuck Leeper]

Might that plug come from cyl #3???

 

[ikle]

Might that plug come from cyl #3???

No cyl #1, unless I mixed them up some how, but I am pretty sure I didn't but you never know lol.

 

[ikle]

Chuck were you thinking a wiped out cam lobe for #3 exhaust valve ?

 

[Chuck Leeper]

Chuck were you thinking a wiped out cam lobe for #3 exhaust valve ?

Yep...

 

[ikle]

Yep...

Chuck if I have a cam lobe being wiped out would a compression test indicate this, if so should I do it "cold" or "warmed up to operating temps" Thanks, Kyle.

 

[Chuck Leeper]

A comp test may do it. I'd do it as warm as possible.
A. All the plugs out, orange wire disconnected, throttle blocked wide open.
Also, pull the valve covers and take a look at how the rocker motion compares.

 

[earlbrown]

and to expand on chucks thought.... a compression test may not.

It's possible to have an exhaust lobe in the process of wiping and have a normal compression reading. The best way it to pop the rockers off and put a dial indicator on the pushrods.

 

[ikle]

A comp test may do it. I'd do it as warm as possible.
A. All the plugs out, orange wire disconnected, throttle blocked wide open.
Also, pull the valve covers and take a look at how the rocker motion compares.

Well do thanks for the help.

 

[ikle]

and to expand on chucks thought.... a compression test may not.

It's possible to have an exhaust lobe in the process of wiping and have a normal compression reading. The best way it to pop the rockers off and put a dial indicator on the pushrods.

Ok thanks, I hope the cam isn't the issue I wouldn't know who to bring it too since Otto closed up shop.

 

[ikle]

Ok this weekend my plan of attack is as follows :

1) ohm out plug wires
2) check the porcelain on spark plug in question for a crack and make sure plug wire fully clips onto plug
3) check the temps of each cyl via Infrared temp gun, when engine is up to normal operating temps
4) compression test
5) pull valve covers and check for rocker arm/push rod travel

What do you guys think, am I forgetting anything. Thanks, Kyle.

 

[vacuum 6]

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[earlbrown]

Was your black plug gloss black or flat black?

 

[ikle]

Was your black plug gloss black or flat black?

Flat black

 

[John Larkin]

Do you have any spark plug pliers so you could pull each plug wire while idling and see which on makes a difference in the idle? I don't want you getting shocked. You can pull them from the coil pack instead of reaching down by the engine.

 

[GNONYX]

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[bpman1234]

subscirbed .

 

[precizion818]

Me too.... I have similar issue myself

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