detonation

[jruppert]

I have a 2010 Navigator and seem to be having some detonation and can't quite figure out what the deal is. It all started last year in August. I live in Michigan and drove up to the UP for a trip. I had only had the vehicle for 6 months at that point and had no issues. I filled up on E85, normally regular though. Drove to the UP and used E85 while being up there. When I got back home I went back to regular. I use regular at home because of the lack of E85 pumps in the area. Anyway, I started noticing some pinging on the driver side. This would happen at high gear with load increasing. The minute it shifts out of OD, the pinging will stop. It can be quite noticeable. Fast forward into winter, didnt notice the problem. Spring comes around and the pinging is back. Last September, I changed out the plugs. They were horrible. No fix. I drove for a couple weeks experiencing it and decided to pull injectors. I have a tester that initiates a pump or pulse to the injector. Hooked up pressured air with carb cleaner and injectors appear to be fine. I am beginning to think it could be a coil issue but not 100% sure. I have an actron and no codes to date. No misfires recorded either.

Any thoughts??

 

[Trainmaster]

Are you sure this isn't a misfire? A good scanner will show exactly which cylinder is missing. That tee in your heater hose isn't leaking on a plug, is it?

You could also read the output of the knock sensor vs. timing retard to make sure that's working.

If your problem truly is detonation, and it's in one bank or one cylinder, you may be looking at a valve problem or a lean condition, like a vacuum leak, which should show as a pending OBD code. On a longshot, it could be carbon buildup, but that's doubtful.

Have you tried using a better grade gasoline? If premium fuel makes it go away, then it truly is detonation.

Rule out the coils by swapping them left for right.

If you rule out the coils, you can take a compression test of each cylinder to find the offender.

Those are my thoughts, and only what I would do if I had this problem. I'm curious as to what you find. You are using some pretty crappy gasoline there with that E85 junk.

 

[jruppert]

I am not sure what I am feeling. To me, it feels or sounds like detonation but it could be a simple misfire on a coil. I have yet to see anything show up on my Actron but it is one of the more basic ones.

I used the E85 with a total of 3-4 tankfulls. It was the only time I ever used it. My situation didnt occur until afterwards, at least that is what I observe. I would try swapping coils and see if anything changes.

I noticed the other day what felt like a misfire at idle. So it could be the coils. If it is coils, is it necessary to go Motorcraft route? I only ask because it would be expensive to change out all 8 unless I know which one is bad.

 

[Trainmaster]

No reason to change all the coils. I would strongly recommend finding the offending one and replacing it with a Motorcraft one. But also check the boots; they go bad and should be changed with the plugs.

Lots of people here have had luck with cheap aftermarket coils, but some have just chased around more problems after installing them and finding it to be as bad as the one they replaced.

A good scanner will show the number of misfires by cylinder or "engine balance". That's what you need when you get an intermittent that doesn't throw a code.

Your problem's probably a miss. Just be sure all the plugs were changed. Garages here, at least are known to skip the difficult ones.