DEALER SAYS MILD SPARK KNOCK

[FordTechOne]

As far as the spark knock goes i had that and narrowed it down to spark blow out. ive tried different plugs but its there at high rpms/full throttle. So don't know how to fix.

Is your truck modified?

 

[jamanrr]

A lot of this comes down to different grades of fuels and the amount of ethanol they contain. Tuning can help with some of this but there are updates to the ECU that Ford will do from time to time.

 

[moonjim]

Fordtechone-yes its a Hennessey 600

 

[GCATX]

As far as the spark knock goes i had that and narrowed it down to spark blow out. ive tried different plugs but its there at high rpms/full throttle. So don't know how to fix.

Have you tried to duplicate the noise in 4a, to eliminate the IWE?

 

[isis]

Fordtechone-yes its a Hennessey 600

Found the problem.

 

[Antho]

@RustyNutz I know it makes the noise on 2wd with the IWE engaged. From what i recall, It doesn't make the noise in 4A. I'm almost leaning towards a clutch or something metallic rattling due to a harmonic resonance.

Nice video Antho. Have you tested in 4a?

Not to hijack, but on mine, I tested and confirmed last night my rattle/noise is ONLY present in 2wd, not 4a, and only after 3-5 seconds of WOT (so no vacuum for some time, mostly high RPM 2nd and 3rd). I found TSB 20-2189 which describes pretty perfectly what OP and I are both experiencing, and i have scheduled an appointment with my dealer.

That sucks the other dealers aren't in agreement OP. Look up that TSB workflow, and maybe have a trusted indi mechanic do the vacuum testing, to find out conclusively for yourself if it is IWE vac loss or not. IMO any spark knock is a no-no, and the PCM's datastream monitors and records spark knock sensor activity, so it should be simple to see if the sensor is actually detecting what you are hearing. BUT not happening in 4a makes me pretty confident that it is an IWE vac and not a knock situation.

 

[Badgertits]

Fordtechone-yes its a Hennessey 600

welp- Toss that shit out. Hennessy def their problem. Not exactly best track record there.

 

[Antho]

Did a few runs in 4A and 4A w/sport and cannot gear the noise.switch back to 2wd and immediately comes back. Is it possible that it’s the transfer case clutches? Maybe the cv axle is spinning enough to cause the clutches to make some noise? Wish there was a way to make the cv axle not move at all in 2wd.

 

[Hdaniel85]

So thats the strange rattle I may be hearing at WOT, I've tested this numerous times (never through to use 4A, but will test that tomorrow) and every single time from a dead stop to WOT I can hear it, mainly from 2nd - 3rd gear shifting but it lasts a couple of seconds then goes away. The video previously uploaded here sounds exactly like it...

 

[RustyNutz]

So thats the strange rattle I may be hearing at WOT, I've tested this numerous times (never through to use 4A, but will test that tomorrow) and every single time from a dead stop to WOT I can hear it, mainly from 2nd - 3rd gear shifting but it lasts a couple of seconds then goes away. The video previously uploaded here sounds exactly like it...

Did a few runs in 4A and 4A w/sport and cannot gear the noise.switch back to 2wd and immediately comes back. Is it possible that it’s the transfer case clutches? Maybe the cv axle is spinning enough to cause the clutches to make some noise? Wish there was a way to make the cv axle not move at all in 2wd.

These all sound like mine, and this TSB. Check this link out for the dealer information and testing procedures - explains what it is and what it is doing IMO:
https://static.nhtsa.gov/odi/tsbs/2020/MC-10176835-0001.pdf