false kr where is it comeing from

[jrb1027]

Hey guys, ive posted a few times on here about kr issues but never solved the problem.

First off it has been tuned less than 3 months ago by prj, it didnt change much, but did clean up the kr at shifts.

Symptoms-I show very high kr (as high as 15kr if i dont let up) it happens when i give more than

half throttle under 3k rpm, above that and there is 0 kr. I assume its false because it probably would

have blown up by now if it wasnt.

if you need more information just ask.

btw i was told it could be the exhast it has slp headers i had it on a lift and inspected the downpipe i can not see any

physical rubbing in the tunnel.

[REDCRAPGP]

What's the condition of your motor mounts?

Also check to make sure the sway bar isn't hitting the header..you can flip it around just to be sure that there's plenty of clearance.

[jrb1027]

prj told me the mounts looked good i looked at them and couldnt see any cracking, I dont think the

swaybar is touching because i didnt notice rub marks when i inspected it. Its has gmpp bars do they

have same clearance issues, its lowered too about 1.5in.

[dsmuts]

Just flip it and see

[darkhorizon]

no amount of noise will cause this... Its a wiring or sensor failure. I tried to fix this in the past with a case learn, ICM swap, but honestly I was never able to fix it.

I ended up disabling the knock senesors in the PCM under 3000 RPM completely... Oh well...

[jrb1027]

really? thats seems like it could be detrimental, but i may have to do that.

[SnowFlake]

According to alleged gurus on this board, there is no such thing as false knock.
However, in the real world, something in the engine bay is likely resonating at the same frequency that the knock sensors detect knock below 3k.

Does it happen in all gears?
Is it only when the TCC is locked? IE: When you're cruising on the highway and load the engine to go up a small incline?
What mods do you have?
Check the trans mount and the bottom motor mount located on the underside of the engine near the passenger tire. They can collapse.

[blueguy]

lol guru's. I'm a firm believer in burst/false KR, buddy.

I ALWAYS tell people to check downpipe clearance to the front sway bar and mount condition or anything else that could be making contact giving the knock sensor a false reading.

[jrb1027]

it does happen in all gears.

I believe its only when the tcc is unlocked, doesnt it lock at 2800 or so

Mods- cai, headers, no cat, no res, 3.4 on genv, 1.8 rollers, every suspension upgrade

I will double check the mounts i had it on a lift not too long ago when i examend them i did not see any cracking

[SnowFlake]

The TCC will lock when you're cruising. If you're going 50mph in 4th gear, it'll lock up at like 2000rpm.

[jrb1027]

ok i think i understand, I dont think the tcc being locked or unlocked has any effect on the kr.

[jrb1027]

getting back to what darkhorizon mentions, he suggest I remove the kr sensor from pcm under 3k, does anyone second that.

[SnowFlake]

ok i think i understand, I dont think the tcc being locked or unlocked has any effect on the kr.

This makes me believe even more that it's false knock.
Which is a real thing, clearly lol.

I wouldn't turn the sensor off below 3k... I'd do everything I could to figure out why it's doing it first.
It could even be noise from the transmission, resonating at specific RPM.

[dsmuts]

How would you go about disabling the knock sensors under a certain rpm?

[dsmuts]

nm i figured it out.

[jrb1027]

If my mounts are good, sway bar isnt touching exhast, and trans dipstick is not touching anything, where do i go from here? Do you

have any more suggestions, is it possible to check for trans resonating?

[jrb1027]

on a side note (dsmuts) we live pretty close to each other

[blueguy]

Might not be touching at a standstill, but touching under load, which is where the KR is coming from.

Also, mounts could appear fine, but you need to actually remove the wheel flashing and inspect them closely.

I'm sure one of the two is the culprit.

They're known for blowing out and failing, even if fairly new. That's why you should either get poly lowers and rattle your teeth apart, or get solid rubber replacements, you just want to avoid the factory fluid filled replacements.

[dsmuts]

If you wanna come over sometime I could look it over for you.

[jrb1027]

I might do that sometime if youll take me for a ride in your car lol ill pm you my number