CEL Won’t GO AWAY! HELP!

[luca1290]

The thing is that the misfire sticks to Cyl 1, so it should be something with that and you already tested the obvious.

I'll do a compression test and borescope it. If it's a cracked piston the sooner you find out the better it is, you don't want things getting worse.

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[TheNetcode]

The thing is that the misfire sticks to Cyl 1, so it should be something with that and you already tested the obvious.

I'll do a compression test and borescope it. If it's a cracked piston the sooner you find out the better it is, you don't want things getting worse.

yea that is what I’m worried about. The car only has 31k miles which would be surprising if that was the case, I mean I do drive pretty spirited lol. I’m going to take it in to a mustang performance shop here locally where they are going to do a compression test and bore scope.

 

[ORRadtech]

yea that is what I’m worried about. The car only has 31k miles which would be surprising if that was the case, I mean I do drive pretty spirited lol. I’m going to take it in to a mustang performance shop here locally where they are going to do a compression test and bore scope.

Have them do a leak down test as well. A weeping headgasket can cause that too.

 

[TheNetcode]

Wouldn’t a cracked piston cause acceleration or idling issues? Like I said before…it runs just fine. I wouldn’t know there was an issue with the car if it wasn’t for that CEL.

 

[luca1290]

Wouldn’t a cracked piston cause acceleration or idling issues? Like I said before…it runs just fine. I wouldn’t know there was an issue with the car if it wasn’t for that CEL.

Not necessarily, the computer is more sensitive than us in detecting the little variation in acceleration on the tone wheels... Best way to know is go and take a look :-)

 

[TheNetcode]

So apparently after taking it to the shop, they replaced my spark plugs with a 1 step colder and told me I had mine gapped a little too big and did a bore scope and compression test and noted that the compression on both sides of the engine are 240, which is perfect. So no mechanical issues…it idles a bit low around 600ish where it should probably be closer to 800, but they drove it and tested it thoroughly and stated it runs great and are hinting at the possibility that it’s the VMP tune that might be triggering the CEL. They recommended the Lund tune which they stated runs into fewer issues than VMP. Is this true?

 

[Magony15]

My VMP tunes never threw a CEL and needed no revisions unlike my Ortiz tune. My idle was 650 which is what stock is. You should have a 93 tune from them as well. I'd load that back in along with a bottle of a good fuel system cleaner. Remove the catch can temporarily and try the stock system.

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