How do i check to see if the knock sensor is working?

[potbelly]

i got my engine rebuilt 2500 miles ago. i went to install a knock guage and found that the mechanic didnt install the knock sensor. so i got a used one and installed it along with a scan master. so i ended up not installing the knock guage. i have not got knock on the scanmaster yet, in 3 weeks of everyday driving. so i bought a new sensor to see if the old one is broken. installed it and still no knock what so ever. i wish i was blessed with a no knock engine, but i know better. is there a way i can test it? maybe the sensor wire dosent work? maybe tork down the sensor more. its hand tight with a 1/2 turn.

 

[xrunner123]

I believe you can just tap with a wrench somewhere near the sensor with the engine running.

 

[ttypewe4jim]

First of all you need to tourqe the knock sensor to 14 Ft-Lbs or 19 N-M Then with the key on but the engine off tap the coil pack with the handel end of a screw driver and have someone watch your scan master for knock (it shouldnt take to hard of a "tap")


HTH
Jim Barnes

 

[3.8Illusion]

run 25 psi with pump gas and watch the scanmaster at least thats what i do. then its time to check cylinder compression

 

[potbelly]

ok, i torqed the knock sensor to 14 lbs. tapped all around the knock sensor and coil pack, im still getting no knock what so ever.
what is the wire input to the computer that runs to the knock sensor, i am going to hard wire the knock sensor back to the computer with my own wiring. I need to know the pin location and wire color for the knock sensor input in the computer harness. Or is there any other suggestion's availible?

 

[BoostKillsStres]

The engine must be above I believe 1000RPM for the ESC to function, stuff a folded wad of paper in the TB arm for higher idle and try the tap test again.

 

[potbelly]

 

[BoostKillsStres]

In other words, the ecm code skips the knock retard functionality unless the engine is running above 1000 RPM. So force the engine above 1000 RPM then retry your tap test around the knock sensor and see if you register knock on your scan tool.

 

[strikeeagle]

Not to my experience. I take a long extention and tap the intake/block near the sensor, at IDLE. SM goes bonkers. I wouldn't tap the coil pack - the delicate electronics in the coil pack/ignition module may not like that...

strike

 

[BoostKillsStres]

Strike, are you sure about that? What chip type are you running? Just curious. Here's the code from the ROM area: checks for runtime, coolant temp and min RPM, spark retard calc is branched around if these 3 aren't met:

E611: BC 31 74 CPX $3174 if (X < 'SEC' IF ENG RUNTIME < THIS SKIP ESC (=1))
E614: 25 42 BCS $E658 goto SkipESC
E616: D6 1E LDAB $1E
E618: F1 31 79 CMPB $3179 if (Coolant < 'DEG C' ESC COOLANT CUTOFF (46.4 DegF))
E61B: 25 3B BCS $E658 goto SkipESC
E61D: 96 1A LDAA $1A
E61F: B1 31 76 CMPA $31 if (A < 'RPM' CUTOFF FOR ESC RETARD INCREASE (=1000))
E622: 25 4B BCS $E66F goto $E66F

In my testing below 1000 RPM I can see the knock register on my Caspers knock gauge since its tied directly to the knock sensor but no knock registering on Directscan because the RPM limit isn't being met. Raise the RPM over 1000 then both devices show the knock.
HTH

 

[strikeeagle]

BKS,

That good info. To be honest, I'm talking about my experiences with my Casper's knock gauges (no longer installed), not my SM. I'll have to check the SM and see what it does at idle, if anything. Chips-wise, using ME's now.

What you say makes sense - I can see the factory "suppressing" knock at idle, so that it doesn't become a nuisance. I'll report back...

strike

 

[potbelly]

i finally saw knock today! thanks to boostkillsstres. at 1000 rpm, my freind tapped the knock sensor lightly with a wrench and i finally saw knock. i guess im lucky for my engine to not have knock at all. thanks to all who replied

 

[BoostKillsStres]

No problem, keep up the good tuning