DEALER SAYS MILD SPARK KNOCK

Antho said:

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.

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Your results indicate that the IWEs (hub disconnects) are partially engaging under heavy throttle, causing the noise. The hubs are held in the released position by vacuum, so when engine vacuum drops due to heavy throttle, the hubs can start to engage if there is an issue with the check valve or a vacuum line leak. You won’t hear the noise in 4WD because the hubs are already fully engaged and vacuum is not being applied.

The TSB posted by @RustyNutz instructs the dealer on how to resolve the issue.

FordTechOne said:

Your results indicate that the IWEs (hub disconnects) are partially engaging under heavy throttle, causing the noise. The hubs are held in the released position by vacuum, so when engine vacuum drops due to heavy throttle, the hubs can start to engage if there is an issue with the check valve or a vacuum line leak. You won’t hear the noise in 4WD because the hubs are already fully engaged and vacuum is not being applied.

The TSB posted by @RustyNutz instructs the dealer on how to resolve the issue.

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Thanks @FordTechOne I still get the noise when the hubs are engaged. I removed the vacuum line at the iwe and still persist.

moonjim said:

Fordtechone-yes its a Hennessey 600

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My recommendation would be to contact Hennessey; the dealer won’t be able to help due to the modifications.

Antho said:

Thanks @FordTechOne I still get the noise when the hubs are engaged. I removed the vacuum line at the iwe and still persist.

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Did you remove both sides?

FordTechOne said:

Did you remove both sides?

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@FordTechOne Yes. I removed vacuum on both sides.

Also noticed that if i accel in 4A i dont get the noise but if i switch to 2wd it makes the noise on deccel from 5k to 4k. If i accell in 2wd i get the noise in accell and decell from 5k to around 4k.
@Anthony Palazzolo You mentioned that yours is fixed? What exactly was done?

Same here , disconnected the IWE check valve and still persists ,,

RustyNutz said:

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

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I tested mine in 4A today, I did this multiple passes and it fixed the issue. Once I reverted back to 2WD the noise came back at WOT. When I initially brought it to the dealer for my 2nd oil change they said they could not replicate it, I think I need to take them for a test drive and show them what the noise is.

I will also let them know about that TSB and what you all have given information about here with the IWE. Thanks all, I will report back after I bring my truck in to the dealer to have them check it out.

Good luck ! Yes plz keep us posted

I had my IWEs replaced and cam phasers replaced by ford no problem. Hennessey is just a tune and adding intercooler ect. Not at all unlike any of these other tunes. People on this forum are so crazy about Hennessey, who cares.