Please Help With Engine Diagnosis; Sputtering, Oily Plugs, can't hold idle or A/F - Ford Mustang Forum
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post #1 of 43 (permalink) Old 06-19-2007 Thread Starter
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Please Help With Engine Diagnosis; Sputtering, Oily Plugs, can't hold idle or A/F

Last week I changed my spark plugs. To do this with a Kenne Bell supercharger it's must easier to reach the #4 plug if you take the intake tube and throttle body off. This requires disconnecting the throttle position sensor and the actuator connectors. I changed the plugs, put everything back together and drove off to go shopping. It ran like a champ, just like you'd expect with new plugs. I drove about 60 miles, came home and parked.

The next moring the car would barely start. And when it did it was sputtering and unable to hold it's idle and air/fuel ratio. It would start out at 14.7 at idle and slowly dip down to off the scale, below 10:1. It would recover, go lean and start the process all over, the whole time unable to hold a steady idle. When I tried giving any gas it would sputter badly.

Today I took out a spark plug to look at it and it was completely covered from the tip to the threads in an oily goo that smelled like gas. It took the rest out and they are the same, all covered in oily gas goo. This is after only 60 miles on new plugs.

Why did my car suddenly stop working? My first thought was that a MAF sensor or O2 sensor has gone bad. I data logged the MAF and it seems to be working although it's hard to tell since the car runs horribly if at all. But I could see it's voltage rising as I added throttle. I have not checked the O2 sensor yet, I though I'd just get a new one.

Does anyone have any ideas what has happened to my baby? What sensor having to do with A/F can just stop working. Is that theory even sound?


2005 Mustang GT with 300 ci 04 Cobra iron block, Kenne Bell 2.6l twin screw, P&P S3 Heads, SS valves, Comp S3 cams, Currie 9+ 9" rear end and DS, Hurst shifter, BMR K-member, A-arms, LCAs & UCA, JBA long tubes & mid-pipe, Accel COPs, Dual GT500 fuel pumps, much more...
670 RWHP, 640Tq @ 16 psi & 6400 RPM
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post #2 of 43 (permalink) Old 06-19-2007
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I'm going to need to think about this one for awhile.


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post #3 of 43 (permalink) Old 06-19-2007
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Couple of possibilities.Oil might be getting past the rings or valve guides, though I doubt you'd see this overnight like you did. Plus you haven't recently had any major internal engine work done. Another possibility, and far less expensive, is you might just have a plugged PCV valve.

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post #4 of 43 (permalink) Old 06-19-2007
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Quote:
Originally Posted by 5twenty View Post
Why did my car suddenly stop working? My first thought was that a MAF sensor or O2 sensor has gone bad.
Pull the MAF sensor and give it a good spray with brake cleaner. Spray the little hole real good. Make sure it's completely dried before you try to start the car.

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post #5 of 43 (permalink) Old 06-19-2007
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Another thought... Could the KB be leaking internally into the intake?? Just thinking out loud.

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post #6 of 43 (permalink) Old 06-19-2007 Thread Starter
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Mark, those are all great suggestions that I will look into:

Where is the PCV valve?

I don't think the substance is oil as is smells very strongly of gas.

I will check the MAF tonight. Got to get the bumper cover off to get to it.

KB, like you, says to check air intake leaks and vacuum leaks. I don't think that is the issue.

2005 Mustang GT with 300 ci 04 Cobra iron block, Kenne Bell 2.6l twin screw, P&P S3 Heads, SS valves, Comp S3 cams, Currie 9+ 9" rear end and DS, Hurst shifter, BMR K-member, A-arms, LCAs & UCA, JBA long tubes & mid-pipe, Accel COPs, Dual GT500 fuel pumps, much more...
670 RWHP, 640Tq @ 16 psi & 6400 RPM
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Dan, the PCV valve is integrated in the driver-side valve cover.
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Quote:
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Dan, the PCV valve is integrated in the driver-side valve cover.
That went away with the S/C. The nipple now connects to an oil serarator then to the back of the S/C.

2005 Mustang GT with 300 ci 04 Cobra iron block, Kenne Bell 2.6l twin screw, P&P S3 Heads, SS valves, Comp S3 cams, Currie 9+ 9" rear end and DS, Hurst shifter, BMR K-member, A-arms, LCAs & UCA, JBA long tubes & mid-pipe, Accel COPs, Dual GT500 fuel pumps, much more...
670 RWHP, 640Tq @ 16 psi & 6400 RPM
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post #9 of 43 (permalink) Old 06-19-2007 Thread Starter
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From the work shop manual.

The HO2S (heated oxygen sensors) give input to control the flow of fuel. When my A/F dipped down it wasn't controlling fuel flow well, which may have gummed up the plugs.

My small pea brain still thinks it's about the O2 sensors or maybe MAF in some way.

2005 Mustang GT with 300 ci 04 Cobra iron block, Kenne Bell 2.6l twin screw, P&P S3 Heads, SS valves, Comp S3 cams, Currie 9+ 9" rear end and DS, Hurst shifter, BMR K-member, A-arms, LCAs & UCA, JBA long tubes & mid-pipe, Accel COPs, Dual GT500 fuel pumps, much more...
670 RWHP, 640Tq @ 16 psi & 6400 RPM
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Is it the plugs in both banks?

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Quote:
Originally Posted by 5twenty View Post
That went away with the S/C. The nipple now connects to an oil serarator then to the back of the S/C.
Ah, that's right, my bad...

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Quote:
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Is it the plugs in both banks?
goo x 8.....all of 'em.

That fact does seem to throw suspicion away from O2 sensors since there is one for each bank.

2005 Mustang GT with 300 ci 04 Cobra iron block, Kenne Bell 2.6l twin screw, P&P S3 Heads, SS valves, Comp S3 cams, Currie 9+ 9" rear end and DS, Hurst shifter, BMR K-member, A-arms, LCAs & UCA, JBA long tubes & mid-pipe, Accel COPs, Dual GT500 fuel pumps, much more...
670 RWHP, 640Tq @ 16 psi & 6400 RPM
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Quote:
Originally Posted by 5twenty View Post
goo x 8.....all of 'em.

That fact does seem to throw suspicion away from O2 sensors since there is one for each bank.
I guess it could be the tune??? You sure the A/F readings you got are accurate?

A possible solution could be running a hotter plug but I don't think that's the best idea.

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Quote:
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I guess it could be the tune??? You sure the A/F readings you got are accurate?

A possible solution could be running a hotter plug but I don't think that's the best idea.
I reflashed. But this is GO/NO Go overnight. Something snapped.

2005 Mustang GT with 300 ci 04 Cobra iron block, Kenne Bell 2.6l twin screw, P&P S3 Heads, SS valves, Comp S3 cams, Currie 9+ 9" rear end and DS, Hurst shifter, BMR K-member, A-arms, LCAs & UCA, JBA long tubes & mid-pipe, Accel COPs, Dual GT500 fuel pumps, much more...
670 RWHP, 640Tq @ 16 psi & 6400 RPM
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Quote:
Originally Posted by 5twenty View Post
I reflashed. But this is GO/NO Go overnight. Something snapped.
What do you mean something snapped??


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