knock question

[sleeperstang199]

I know watching and logging for knock can drive you crazy but i haven't had any problems till now. I just installed my turbo xs FMIC this past Saturday and ive started to knock. it started out small .35-.7 so i wasn't to worried. I made sure that my FP is ok and its at about 1700-1750PSI at wot. It seems i always knock right as im shifting. I didn't get my Silicone recirc hose from street unit yet so im hoping this is my problem since i know im running pig rich between shifts. But i knocked 2.45, 2.75 and a wait for it.............. 5.76 today!!!!! should i be worried? and how worried? i have datalog graphs but cant figure how to make them into a pic to post.......thanks for the help

 

[BillTheCat]

Seems like every day as I get on the interstate heading to work... engine is already warmed up... I accelerate to 75-80mph & let off the gas, and knock spikes to anywhere from 6-8 momentarily. Not even shifting, just letting off the throttle to cruise. Also happens in the middle of highway cruising every so often. (I had to turn my knock alarm up to 6 on the Dashhawk in order to stop seeing the damned thing blink like a Xmas tree)

Doesn't mean you don't have problems. Just means that if you do, I do. And my only mod is a Forge BPV, but the knock was worse before I installed that.

 

[240ka]

wow, that sucks. im getting Zero knock. most i have ever seen is .3

bad gas maybe? what are you using

 

[cpolly69]

i would say 1st don't worry about it unless everything's up to normal operating temp. 2nd depending on your mods switch to 1 step colder plugs - ever since i did i saw way less - 3rd make sure the gas is 93 or better 4th almost everyone gets this slight knock at around 3200 (there's massive discussion threads about it out there) so i would stick to worrying about it if it's happening while you are going into boost or if it's actually happening any time while you are accelerating and you feel it and last if you really know what you are doing you can chase fixing it with one of the tuning options (ap or sb)

 

[sleeperstang199]

well as far as gas i use sunoco 93. but that has up to 10% ethanol and i think that might be some of the problem there(damn corn). I also thought that maybe my MSCAI in short ram mode might be a problem to so i had ordered a Nano from paledrider that gets here today hopefully. I guess i have a few things to check first......s*** just drives me nuts!!! lol bill i will let you know if i have a problem that way you have a heads up haha. thanks

 

[djthom]

our engines have gremlins in them!!!

seriously people are not finding answers to the KR ish. only that it is mostly partial throttle knock that makes our motors go boom. don't believe me? drive around in 4th gear modulating thrttle/speed for a bit and watch you KR
go all over the place...


check out the "other" forum and you can read pages and pages of info on KR and blown engines...

but at this point i haven't seen a fix or people being able to eliminate this other than with talismans and strong ju ju!

but what the hell do i know...

 

[mr_mazda329]

our engines have gremlins in them!!!

seriously people are not finding answers to the KR ish. only that it is mostly partial throttle knock that makes our motors go boom. don't believe me? drive around in 4th gear modulating thrttle/speed for a bit and watch you KR
go all over the place...


check out the " other " forum and you can read pages and pages of info on KR and blown engines...

but at this point i haven't seen a fix or people being able to eliminate this other than with talismans and strong ju ju!

but what the hell do i know...

More than most people. The partial throttle knock is crap because of the factory tune on the ECU for close/open loop mode transition. You can see 5-10psi at partial throttle and your Command AFRs and Actual AFRs will not dip below 13. Thats no good at all. The Cobb AP or CPE standback will not solve this. The Cobb ATR is the only hope so far.

OP..the best thing you can do is get colder plugs, and keep running 93oct. Also.... what are your BATs like? (boost temps)

 

[djthom]

More than most people. The partial throttle knock is crap because of the factory tune on the ECU for close/open loop mode transition. You can see 5-10psi at partial throttle and your Command AFRs and Actual AFRs will not dip below 13. Thats no good at all. The Cobb AP or CPE standback will not solve this. The Cobb ATR is the only hope so far.

OP..the best thing you can do is get colder plugs, and keep running 93oct. Also.... what are your BATs like? (boost temps)

can you explain this? just trying to understand and needing a bit more info.

thanks!!!

 

[mr_mazda329]

can you explain this? just trying to understand and needing a bit more info.

thanks!!!

If your hitting boost around 5-10 psi and not getting the right amount of fuel (AFRs), this will give you your Knock (detonation). Partial throttle makes your AFRs really high, almost like cruising (not good for boosting). If your partial throttle with boost, your AFRs need to be around 12.5 ish to be safe.

 

[djthom]

got it!

 

[240ka]

well as far as gas i use sunoco 93. but that has up to 10% ethanol and i think that might be some of the problem there(damn corn). I also thought that maybe my MSCAI in short ram mode might be a problem to so i had ordered a Nano from paledrider that gets here today hopefully. I guess i have a few things to check first......s*** just drives me nuts!!! lol bill i will let you know if i have a problem that way you have a heads up haha. thanks

i use Sunoco and Mobile. havent gotten any knock on either.

i use to have a MSCAI and sold it to get a Nano.

but i think i want to have another CAI on hand so i can switch between it and the NANO. if you sell the MSCAI, how much will you sell for

 

[MSMS3]

Question to to the OP: Do you have stock MM or aftermarket? Do you have an engine dampener? How is the FMIC connected mechanically to anything than can transmit vibration to the engine?

There are mechanical vibrations that can drive your knock sensor crazy especially at certain rpm's where there is mechanical resonance with the frequency that those objects vibrate.

Also check for any loose or less than fully tightened bolts or screws that attach anything to the engine block or cylinder head, as that vibration gets transmitted to the knock sensor. Mounting your new FMIC may be producing some vibtation that it getting transmitted to the block or cylinder head or something rigid bolted to either of them.

What I recommend may be a wild goose chase, but these are simple alternative explanations for sudden and unexpected changes in knock.