Phantom knock issue
 

I recently bought a 92 Talon Automatic that had snapped a timing belt. Rebuilt and installed a new head amongst many other things. Engine runs great except heavy heavy knock is bieng picked up.

Engine picks up the knock only after 18-20% throttle (Whch is when I believe the ecu decides to start caring).

It immediatly jumps to 35-43 counts after 20%.

Brand new knock sensor

Verified timing is at 5* BTDC

Verified no boost/vaccum leaks

If anyone has dealt with this issue with any luck Id apprecaite your input.
As of now im going to look for exhaust rattling somewhere as this is obviously phantom knock.

Re: Phantom knock issue
 

Only thing I can take a guess at would be how tight the knock sensor is, I've heard overtightening them can make them read super sensitive

Re: Phantom knock issue
 

What are you tuning with? Have a wide band? How aggressive is your timing? Any logs?

Re: Phantom knock issue
 

Can you hear audible lifter tick?

Re: Phantom knock issue
 

From what I have been looking into, over-torquing the sensor can cause a lot of problems and apparently you need to position it correctly as well.

So i guess check the positioning and torque first if you haven't already.

Re: Phantom knock issue
 

Everything is completely stock exept a k&N filter and the turbo is a 14b instead of 13g. Its occuring under such light load I dont think either of these is the problem.

I installed 3g lifters, I do not hear any lifter ticking.

As for how tight the sensor is and its location, Ill verify I have it in the correct spot. I do not have my torque wrench or crow foot here, but I have tried testing with it at differant torque values and the problem still occurs.

Re: Phantom knock issue
 

I usually just go a bit over hand tight with a wrench.

Re: Phantom knock issue
 

Verified location, good, lightly snugged the sensor, no differance. Found a small exhaust leak at the flex pipe, think this would cause it?

Re: Phantom knock issue
 

Things Ive tried

Moved spark plug wires away from each other to verify there is no spark jumping, no differance.

Temp fix exhaust leak at downpipe, no differance.

Removed damper pulley and ran to find no differance.

Seems to occur only when slightly warm and warmer (dont know if its just the ecu ignoring it earlier) and when you blip the throttle past 18%, even in nuetral with no load. If you hold it steady past that it does not register any knock.

Re: Phantom knock issue
 

Problems appears to be affected by load more than engine speed. Blipping the throttle to 20% the knock counts will hit a random number between 10-23 then back down as I hold it at 20% throttle. If I put the transmission into gear and hold the throttle at 20% and put a load on the engine, the knock counts will peg at 43 and stay there.

Re: Phantom knock issue
 

sounds like it could be from clutch or flywheel vibration? idk just throwing out some ideas phantom knock isnt fun to track down this much i know..

Re: Phantom knock issue
 

Actually this is an Automatic, I held the car still with the brake and started to stall the converter with 20% throttle to see 43 counts of knock immediatly.

Re: Phantom knock issue
 

Update on this:

Swapped over my exhaust fom my other Talon, which has no leaks, problem stil occurs. Verified cam timing, spark timing. Replaced spark plugs (BPR7ES) and wires, still no change.

Checked for any dead lifters, found none. Bleed one out on purpose and ran engine (when cold as it does not occur when cold), to find the sensor did not pick up any knock from the klacking lifter. Lifter quieted down after 15 seconds.

Hooked up a wideband and ran engine at 20-22% throttle with transmission in gear, car stationary, from 56 degrees until 150 degrees. Picked up no knock whatsoever until 150 degrees. Afr's were 14.1-14.7 entire time. At 150 it started to pick up 13 counts. It seems to happen like clockwork every time it gets warm, it starts to pick it up.

I am going to perform this test again once it cools.

Re: Phantom knock issue
 

Where did you get the knock sensor from? I would try warrantying out the knock sensor and try a new one. I didn't see a question to the "Mechanical Noise" issue. Any problems with the car we need to know about? Exhaust leak like you described shouldn't give you a knock issue, and not that high. Did you have to change the wire going to the sensor or no? If not, are there any breaks, weak spots on the wire that may interfere with the signal?