Knock sensor problems

[HIGHPSI4]

My knock sensor is giving me a fit. Typically it pulls timing and dumps all the boost at low throttle. It does not pull all the timing at WOT. The knock sensor has <3000 miles on it. I have tighted, loosened and even pulled it from the block. When I pulled it from the block I got the code 31 and still displayed a knock sum on my logger. I have checked the wiring harness and ground and have switched ECU's and I still have this full knock sum knock. I am going to check the knock sensor with a scope today and have ordered a new knock sensor. Anybody have a clue what's going on. Your input is greatly needed. Thank you!

 

[moonstation2000]

mine is doing something similar , 43 counts of knock all too often at partial throttle. when i lift off the gas and get back on hard - no knock.
do you have ticking lifters? i'm leaning towards this being the answer on my car

 

[92tsiawd84]

I have been struggling with the same problem as you two but have not gotten any answers on my post. I have searched under phantom knock and found it to be acouple of problems:

-Balance shafts out of balance
-knock sensor (screwed in too tight/loose, or faulty
-too much carbon on pistons where the carbon on the pistons creates a coating which hits the head.

Look under search for the procedures of fixing.

I have tried putting seafoam in my gas and it seems to be having an effect. I noticed that I was building knock while reving in neutral and that the knock seems to drop after a few revs. After going through 3/4 tank of gas (with seafoam) and reving before I launch the knock has lowered. Before, I was hitting 43 counts of knock in first gear and it would drop down to 6 counts in second. Now, before launching, I rev a few times and get a max of 12 counts through 1st, 2nd, and part of 3rd.

 

[Motohead1]

Hey Dave. Ok guys i have a sugestion. I want yall to unplug the Knock sensor and see if ya still get knock like Dave is. If ya still do then I am thinkin there must be some inductance voltage bleeding over into the knock harness. It is shelded but if the sheilding is broken anywhere there can be blead over voltage from any adjacent power wire. this is a weird problem and only investigation will find the solution. good luck.

 

[ECLIPSE4x4]

I know this may be a shot in the dark, but has anyone tried the MCCC . I used it and it helped out a lot.

 

[moonstation2000]

what is the mccc?

 

[ECLIPSE4x4]

Originally posted by moonstation2000
what is the mccc?

Mopar Combustion Chamer Cleaner. It gets rid of a lot of carbon deposits and crows on the top of the pistons.

 

[HIGHPSI4]

I unhooked the Knock sensor but it gives me the code 31 and the ECU goes in to safemode and displays knock to pull timing due to lack of a signal. I tried grounding the sheilded ground wire but that did not help. I have two cans of MCCC and will do that tonight. I talked to another mechanic and he said bad motor mounts and exhaust noises can be picked up as knock by the sensor.

 

[92tsiawd84]

I haven't got around tp trying it yet myself. That was my next step. I have put seafoam in my gas and have gone through 3/4 tank so far. I don't want to make any WOT runs with the lower octane. I use premium (92 in MN) and the seafoam degrades that. I just want to be careful.