Excessive detonation

[Blakshukvw]

I just purchased an 04 marauder with 200k miles.It's in great shape and solid mechanically. The seller who owned it since 05 told me he had the spark plugs replaced less than 5k miles ago. He implied that he had never replaced the coils. It appears that oil changes belt replacements plugs and the typical oil filter housing gasket replacement were about the only work the engine had ever needed.
The problem is I'm experiencing some very bad detonation under hi gear low rpm load and wot. The seller was an older guy and I know he never drove it hardbut be said he always used 91octane or better. Still I think it's severely carboned up. I drove it with a snap on scanner and watched the fuel trims and they seemed right on so I'm certain it's not lean. Also watched the knock sensor and it was counting but I'm not certain what that is telling me. The timing was being pulled during the detonation down to around 8degrees so it appears the knock sensors are doing there job.
Tried to perform a contribution test but the car would only spin the tires when the engine load got higher so I couldn't really get a good result from this. I did see an occasional spike from cyl 5 and 7 coil at idle but not excessive but maybe that's enough. It's real hard to tell what the ignition is doing while driving because the load changes with throttle changes.
I'm going to seafoam the engine and check the gap on the plugs. Probably clean the maf even though the fuel trims were good. Anyone have ideas? Could the timing chains be stretched and cause this? I don't hear the typical rattle on start up that is consistent with guide failure. Any help is appreciated.

[Turbov6Bryan]

At least change the fuel filter and start doing some injector cleaner... I could hear My 210K marauder ping and knock at wide open throttle before I started doing injector cleaner finally stopped doing it after about 10 bottles in a year

It could have a aggressive tune in it, and lost the tuner box, or have a chip in it

These have tensioner on the guides, so if there is chain stretch it will not be affected on the tight side. That's what I was told... if it did stretch, the small tensioner take up the slack???

Do you hear chain slap on initial startup before the tensioner has oil pressure?

I would say it's high timing, dirty injectors, and your 91 has too much ethanol in it.
I'd put ngk plugs into it, and start getting the injectors cleaned out

[Turbov6Bryan]

Holy *****. Blue springs Mo

What are you doing for lunch ? I'm in Independence Mo
Exit 13
573-286-1699 text
Bryan

[Blakshukvw]

The seller told me he had ford change the shift points lower so it got better mpg. If you just putz around it does shift early. He said there was no upgrade to engine software.
He also claimed he only used non ethanol fuels.
I don't hear any chain slap.
What ngk plug specifically and what fuel treatment did you use?

[Blakshukvw]

Holy *****. Blue springs Mo

What are you doing for lunch ? I'm in Independence Mo
Exit 13
573-286-1699 text
Bryan

Hello 816 brother. I'm working today and lunch is over. I would like to get together with another MM owner though.

[RF Overlord]

your 91 has too much ethanol in it.

Pure ethanol has an octane rating of 99...not sure how that would contribute to excessive pre-ignition or detonation.

[RF Overlord]

The seller told me he had ford change the shift points lower so it got better mpg. If you just putz around it does shift early.

I'd be skeptical of that. Most Ford dealers won't mess with the tuning other than to re-flash the PCM to the latest update. The factory shift points in the car are very low to begin with and most people get a tune that includes modifying the shift points for better overall performance.

Having said that, if the PO really did have the shift points lowered, that could cause your pinging as the engine is lugging too much. Call Marty.

[Zack]

Holy *****. Blue springs Mo

What are you doing for lunch ? I'm in Independence Mo
Exit 13
573-286-1699 text
Bryan

Da fuk this isn't craigslist casual encounters or backpage. Chill brah

[Turbov6Bryan]

Pure ethanol has an octane rating of 99...not sure how that would contribute to excessive pre-ignition or detonation.

When you run straight ethanol (say the tune is for E85 )your consuming twice the amount of fuel compared to gasoline.

What happens when you have stock injectors and run ethanol? You run out of injector duty cycle and have detonation. The injectors can't keep up with the amount of fuel needed,stack on 200k worth of tarnish and you've got a recipe for preigition knock.

High compression engine and using ethanol isn't great, pick all ethanol or all gasoline and save the ring lands

[Turbov6Bryan]

Da fuk this isn't craigslist casual encounters or backpage. Chill brah

Haha. Why not? Lmao

[Blakshukvw]

When you run straight ethanol (say the tune is for E85 )your consuming twice the amount of fuel compared to gasoline.

What happens when you have stock injectors and run ethanol? You run out of injector duty cycle and have detonation. The injectors can't keep up with the amount of fuel needed,stack on 200k worth of tarnish and you've got a recipe for preigition knock.

High compression engine and using ethanol isn't great, pick all ethanol or all gasoline and save the ring lands

I understand all this but none of it matters because as I stated above he only used non ethanol fuels.

[Blakshukvw]

I was considering calling Marty but I want sure if he actually increased the timing. That's the last thing it needs right now. Does he write trans software?

[RubberCtyRauder]

I was considering calling Marty but I want sure if he actually increased the timing. That's the last thing it needs right now. Does he write trans software?

talk to Marty, his tune changes trans shifting so it does not go to OD so fast and hunt and peck for a gear. just talk to him, since you can datalog, he can help diagnose

[Blakshukvw]

Will do. Thanks.

[justbob]

Da fuk this isn't craigslist casual encounters or backpage. Chill brah

Now that gave me a chuckle!


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