Update on Scored Cylinders

[gilbenja]

Hi all - a quick update below

I pulled the car from Galpin Ford after they couldn’t determine the cause of the P0300. They mentioned contaminated fuel but said their initial concern was a base engine issue and that the engine would need to be torn down.

*noting that I added in iso heet to my fuel and put in new Chevron gas and the car was fine driving moderately hard.
However, as soon as I did a wide open throttle in 2nd gear to red line, the engine flashed again.

I then took it to an independent mechanic. He reviewed the cylinder scoring photos and said it’s not a good sign, but given the car only has 13k miles, he felt the engine is currently “fine.” He did say the scoring could worsen over time and even suggested selling the car as something to consider.

Asked for a leak-down test, but he wanted to scan and check coils first. He drove the car and revved it in idle but couldn’t replicate the issue under load. The only thing he found was one misfire on cylinder 5 (only happened once). He swapped the coil from cylinder 5 to cylinder 2, and the misfire followed — so he acknowledged the coil could be faulty. However, since it happens so infrequently , he said it wasn’t worth replacing the coils and to save my money.

Right after leaving, I did a WOT pull in 2nd to redline and the CEL flashed again. I went back, did multiple WOT pulls with him in the car — no light. As soon as he left and I did another 2nd gear WOT pull, the CEL came back solid (not flashing).

When I called him, he basically said I’m driving the car too hard and that high RPM use could contribute to scoring or coil damage. He recommended just not driving it that hard. He also suggested I might be going past 8250 RPM (I definitely was not though and I think he just assumes this since the car revs so high)

My question: since the misfire only occurs under WOT load in 2nd/3rd and the misfire followed the coil when swapped, would you just replace the coils and re-test? What would you guys do next? Thoughts on him saying the car shouldn't be driven like that? (jokingly, he basically said im driving like a maniac.)

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[gilbenja]

*last comment. It seemed like the conversation ended with us agreeing to disagree. I basically said I will not, not drive the car hard -- should I change the coils?

He said I shouldn't change the spark plugs and drive the car normally.

 

[robvas]

Galpin Ford

LOL

That explains a lot.

Asked for a leak-down test, but he wanted to scan and check coils first. He drove the car and revved it in idle but couldn’t replicate the issue under load. The only thing he found was one misfire on cylinder 5 (only happened once). He swapped the coil from cylinder 5 to cylinder 2, and the misfire followed — so he acknowledged the coil could be faulty. However, since it happens so infrequently , he said it wasn’t worth replacing the coils and to save my money.

Right after leaving, I did a WOT pull in 2nd to redline and the CEL flashed again. I went back, did multiple WOT pulls with him in the car — no light. As soon as he left and I did another 2nd gear WOT pull, the CEL came back solid (not flashing).

When I called him, he basically said I’m driving the car too hard and that high RPM use could contribute to scoring or coil damage. He recommended just not driving it that hard. He also suggested I might be going past 8250 RPM (I definitely was not though and I think he just assumes this since the car revs so high)

My question: since the misfire only occurs under WOT load in 2nd/3rd and the misfire followed the coil when swapped, would you just replace the coils and re-test? What would you guys do next?

Buy an new, OEM Ford coil for that cylinder.

Thoughts on him saying the car shouldn't be driven like that? (jokingly, he basically said im driving like a maniac.)

He's an idiot for saying that. But at least he found the issue.

 

[11GT50]

You need to log spark and fuel pressure while it's happening. I've had an issue like this and it ended up being an issue with the wiring harness to the fuel rail pressure sensor.

Download Forscan and get a bluetooth OBD II device then to recreate the issue and report your results.

 

[Inthehighdesert]

Just want to make sure I have this clear. Found a misfire, swapped the coils and it followed. Recommended doing nothing. Sell car.

In all seriousness can’t get my head around not replacing the coil. 30-40$ each or a full set for $250ish depending. It’s a simple swap. Last thing I’d play around with is 7500rpm plus pulls and a misfire condition. Change the coil or coils and go from there. Electrical issues can be a pain in the … . That’s where the particular experience with certain cars comes in to play big time. Even messing with the harness like said above isn’t a huge deal on these cars. The good is you’ve pretty much eliminated the rabbit hole of the cylinders. That was completely unnecessary to start with.

 

[CorralesR]

Just curious. You are doing the WOT pulls on a hot engine right? Changing the coil at this stage is a no brainer. Might even pull the plug and see what it looks like. I'd like to say I'm shocked that this car was misdiagnosed at a Ford dealership. But after spending over 30 years working at Ford dealership service parts I'm not.

 

[Gen 6 Mach1]

I hate to say it as well , all the trades are short young people , and very inexperienced , not all but also with a poor work ethic. I hope and the Tech at the Ford Dealership wasn't a Master Tech. That would be scary.
gilbenja
As stated above replace the coil and a good idea the spark plug ( at least take it out clean it regap . MO you don't need to hit red line all the time test it to 6,500 to 7 k rpms , high RPMs shorten the life span of engine's. Hope all works out .

 

[gilbenja]

Just bought a Bluetooth obd2 scanner. It had two codes. The P0300 random misfire and this code.

I just cleared both codes. So I know drive the car and click the data recording button?

 

[11GT50]

Last thing I’d play around with is 7500rpm plus pulls and a misfire condition. Change the coil or coils and go from there. Electrical issues can be a pain in the …

If the coil swap solves the problem.

If it doesn't then he may have to try to reproduce it. I don't like it either, but without knowing whether it's spark or fuel related and it not showing up until high RPM, there aren't always a lot of ways to find the source of the problem.

Hopefully the coil solves the issue.

 

[gilbenja]

@Inthehighdesert @11GT50 @Gen 6 Mach1

Here are the reports from my live scan diagnosis. Does this tell us anything?

 

[gilbenja]

Just curious. You are doing the WOT pulls on a hot engine right? Changing the coil at this stage is a no brainer. Might even pull the plug and see what it looks like. I'd like to say I'm shocked that this car was misdiagnosed at a Ford dealership. But after spending over 30 years working at Ford dealership service parts I'm not.

Yes, only WOT once engine reaches 190+ degrees

 

[wingnutt]

I would do coil, and all plugs while you’re in there

 

[fiveoboy01]

So the misfire followed the coil and the mechanic said don't replace the coil?

I'd find a different mechanic.

 

[Swtbabybilly]

I know im late to the party and kind of beating a dead horse but id personally change the bad coil with a ford oem coil and do the same to all the spark plugs, you also had a code for the battery if it looks like the original id swap that out ive read people on here that also have 350's saying they get temperamental if the battery is going bad. best of luck

 

[OldbutNew]

What Billy said^^^^.
AND at least one coil. AND a set of properly gapped plugs.

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