FALSE KNOCK

[whipplenight]

Hello, another false knock thread!!

Vehicle: 2017 5.7 8 speed Ram 2wd

Mods: whipple 8 psi, long tube headers, y pipe, legmaker intake and all other basic bolt ons. No internal modifications, truck runs very strong no weird sounds or issues. Great AFR ratio.

Symptoms: False knock picking up as high as 5 volts on the sensors and retarding timing up to 5 degrees depending on the aggression of tuning and level of sensor desensitization. I’ve proved false knock but can not located it.

what I’ve done: Stethoscope over motor and transmission, ran race fuel, had my tune gone over, purchased aftermarket dipstick, cut the oil filter in half to check for metal, checked all mounts and shields, bought another set of new headers, ran injector clear, changed spark plugs to NGK colder for boost gapped at .32

 

[Brandon-w]

Possible injector dumping too much/less fuel?

 

[whipplenight]

AFR is good

 

[Brandon-w]

I'd try unplugging injectors one at a time see if the knock comes out sometimes afrs lie.

 

[whipplenight]

It was knocking when it was n/a before I replaced the injectors For the whipple.

 

[Brandon-w]

Ah ok that rules that out. Do you physically hear the knock or is it on the sensor only? I've heard guys running headers can get knock sensor issues from that dropping their 1/4 mile times from retardation..

 

[whipplenight]

Its definitely phantom knock, no real knock noise and it is retarding timing. The knock sensors are going crazy but no sound can be hear with the ear.

 

[Hemi395]

Have you seen this video? Might want to look into this...

 

[whipplenight]

Have you seen this video? Might want to look into this...

Good find but I’ve replaced the headers for brand new ones trying to elminate that issue.

 

[ScLeCo]

If it's not the sensors themselves, and you've ruled out everything else, it's time to start checking your valve-train/push-rods.

 

[whipplenight]

If it's not the sensors themselves, and you've ruled out everything else, it's time to start checking your valve-train/push-rods.

It’s not real knock

 

[Tim Garceau]

What or who are you tuned with? First thing anyone does on these is decrease the knock sensitivity.

 

[Triumphx]

I would double check the long tubes

 

[whipplenight]

I would double check the long tubes

I completely replaced them with a new set and it helped a good amount but not all the way.

 

[whipplenight]

What or who are you tuned with? First thing anyone does on these is decrease the knock sensitivity.

Diablo tuner with custom email tune gone over multiple times tune checks out perfect. The sensors are already desensitized anymore and there would be no safety net.

 

[whipplenight]

Let me also mention, the knock is only under heavy load you can not cause it by revving in idle or gear

 

[Tim Garceau]

Triple check and make sure you have adequate clearance and hangers tight on all piping. You may want to just replace the knock sensors after that point or if there is a method of verifying their functionality.

Im looking for a set of long tubes if you still have the existing

 

[whipplenight]

Triple check and make sure you have adequate clearance and hangers tight on all piping. You may want to just replace the knock sensors after that point or if there is a method of verifying their functionality.

Im looking for a set of long tubes if you still have the existing

Not sure how to test the sensors they’re only $17 for replacements at the auto parts store. Don’t really care if they’re oem. And the headers just sold brother.

 

[Wild one]

Good find but I’ve replaced the headers for brand new ones trying to elminate that issue.

Did you wrap the headers with header wrap,might be worth your time to wrap them .Who's tuning it for you?

 

[grizzstang]

Are you running Stage 8 header bolts with the lock washers in place?

I have heard the lock washers can play hell with the knock sensors on some vehicles.