My spark plugs dont look too good

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Mar 3, 2004 | 10:25 PM

SHADO

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My spark plugs dont look too good

The other week i took 1 of my spark plugs out to inspect them, as i was unscrewing it i noticed that it came out easily and it wasnt tight, when i took it out i was shocked at the state of the plug, it had brown gunk all over it and dark brown oil, i then took all the others out and they looked the same.
I assumed this may be because i didnt tighten them properly and exhaust was escaping from the cylinder causing build-up on the plugs, so the next day i changed all my plugs with NGK's, and upon inspecting them now they seem to be doing the same thing, the thick brown gunk isnt there yet but they had a bit of dark brown wet oil on them.
What could be causing this and is it something major?

Mar 4, 2004 | 04:28 PM

ImprezaVA

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Joined: Mar 2003

Posts: 137

From: Elkton, Virginia

Car Info: 1998 Subaru Impreza L 2.2

How many miles are on your car? My only guess could be blowby caused by worn piston rings. Tighten the plugs to about 15 ft.lbs.

-Charles-

Mar 4, 2004 | 08:15 PM

Kevin M

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Posts: 18,369

From: Reno, NV

Car Info: 1993/2000/2001 GF4 mostly red

Yes, your car is either running very very rich or it is burning oil. With all 4 looking the same, my guess would be rich.

Mar 5, 2004 | 05:20 AM

SHADO

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I have 110kms on my car, im not sure how many miles this is. Would getting a professional tune up clarify if it is running rich or not?

Mar 5, 2004 | 05:23 AM

SHADO

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Also how can i tell if i have worn piston rings? My car seems to be in perfect condition, i never ever get any smoke out of the exhaust from start up in the morning to redline.
I'll try and post some pics of the spark plugs even though they have only been in about a week.

Mar 5, 2004 | 06:17 AM

ImprezaVA

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Joined: Mar 2003

Posts: 137

From: Elkton, Virginia

Car Info: 1998 Subaru Impreza L 2.2

Quote:

how can i tell if i have worn piston rings?

Compression or vacuum test. Sears sells compression testers for around $50 and vacuum pumps from $30-$70. Or you can go to a shop and have them do it for you, but I don't know how much that will cost you. Get on the internet and search how to read compression differences and vacuum gauge results. Here is a link on reading vacuum gauge results from an intake manifold test. http://www.performanceprobe.com/index2.cgi

Edit: The link isn't taking me directly to the site. Go to that link and click "Do It Yourself" then click "Diagnostics" and then click "Intake Manifold Vacuum Test" and lastly click "click here to diagnose results."

-Charles-

Last edited by ImprezaVA; Mar 5, 2004 at 06:38 AM.

Mar 5, 2004 | 06:55 AM

Kevin M

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From: Reno, NV

Car Info: 1993/2000/2001 GF4 mostly red

Running rich with no significant mods usually comes from a bad oxygen sensor. If you haven't replaced it before, go ahead and do so. You will probably see small gains in fuel economy and power.

Mar 6, 2004 | 03:40 AM

SHADO

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coo thanks alot 4 the great info guys, i'll lets use know how i go.

Mar 6, 2004 | 03:46 AM

SHADO

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ImprezaVA, do those stats only apply to the ford probe? or any car, cos that is a Ford probe site.

Mar 6, 2004 | 03:36 PM

#10

SHADO

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Which o2 sensor needs 2 be replaced? Is it the one on the front muffler just under the gearbox?

Mar 6, 2004 | 04:02 PM

#11

Kevin M

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Posts: 18,369

From: Reno, NV

Car Info: 1993/2000/2001 GF4 mostly red

If your car has 2, it should be the one before the catalytic converter.

Mar 8, 2004 | 06:59 AM

#12

ImprezaVA

Registered User

Joined: Mar 2003

Posts: 137

From: Elkton, Virginia

Car Info: 1998 Subaru Impreza L 2.2

Quote:

ImprezaVA, do those stats only apply to the ford probe? or any car, cos that is a Ford probe site.

The fluctuations in the vacuum gauge readings are the same for all vehicles. However, different vehicles have different compressions and vacuum. Again, accessing the needle on the vacuum gauge will give you the same conclusion on all vehicles.

-Charles-