Low RPM knock at 0 psi

[rouge91]

I am getting knock at lower rpms ~2-3K range when the manifold pressure transitions from vacuum to positive boost. On my logs I don't see anything that stands out as an issue.

I replaced the knock sensor because it didn't look great, but no change.

Any ideas where to look for an issue or what the problem may be?

I have a 92 Laser 6/4 with a 3" exhaust, Big 16g, MBC, 2G MAS, AFPR, 550cc injectors, 255lbh fuel pump, Keydiver chip, balance shafts removed.

Thanks for any help.

 

[Absit]

How much knock? Got a log?

 

[TurboAnything]

I am having the same issue with my AWD 92 with basically the same mods. I even added the some phantom knock code but i can still get the car to do it if i go over the phantom knock threshold like 30% throttle. When mine knocks it can send the stock boost gauge all the way up and the car bogs down. Full throttle is fine 0 knock and i have a very quite motor.

Does this sound like the same issue ?

 

[rouge91]

I am having the same issue with my AWD 92 with basically the same mods. I even added the some phantom knock code but i can still get the car to do it if i go over the phantom knock threshold like 30% throttle. When mine knocks it can send the stock boost gauge all the way up and the car bogs down. Full throttle is fine 0 knock and i have a very quite motor.

Does this sound like the same issue ?

Sounds like a similar issue.

I am getting knock counts of 43 when the car does this.

 

[92_6bolt_1290]

I'm also chasing the same exact issue. I get around the same counts for knock right as I start to transition into boost, always between 2500 rpms and 3500 rpms. Only happens for me at over 50% throttle and will not happen if I ease into full throttle slowly. 92 GSX 6/4 with pretty much the same mods. I still have my balance shafts though, but I have 2G pistons. I almost think it has something to do with how the stock ecu does ignition timing and I will try setting my base timing at 3* before TDC instead of 5*.

 

[CurtC]

Sorry to bring this thread back but has anyone found a solution for this?

I was looking through the forums as I'm experiencing the same exact thing. I don't have any knock at all, except around 2500 to 3000 RPMs. In this range I'm seeing a knocksum of anywhere from 1 to 4 constantly.

I tried pulling timing in this range but I still get the same result. I don't want to mess with my timing map to much as the knock seems to be at various loads under 120 in this RPM range.

I'd like to not have any knock at all. Its worrying me seeing this knock anytime I'm cruising around 2500 rpms.

 

[JusMX141]

Could be anything- dead knock sensor, bad lifters, a/c compressor clutch or another pulley in the accessory system making too much noise, etc.

 

[slow8033]

If you have replaced your knock sensor with a new unit and are sure it's good then you may be able to rule that out. It seems that it only happens at an exact harmonic balance in your rev range. Something is vibrating and causing a false reading at that 500rpm range.

If you ever drive an old crappy beater of any kind, you will notice that the door panel or rusted out exhaust seems to vibrate more at a certain RPM range. This is what's happening somewhere and its giving you counts of knock. Make sure your heat shields, exhaust, motor mounts, pretty much everything is nice and tight.

I know thats not much help, but Justin is right, It could be alot of things.

 

[CurtC]

I'm going to check my knock sensor when I get home. I only owned the car for about a year and a half and I'm not sure if it was ever replaced. The harmonic balancer I replaced, as the last one fell apart.

I'll check for anything loose as well. Thanks a lot for the suggestions.

 

[WisconsinMonSTAR]

Bringing this one back because I have a near identical issue and I see that there was never a solution posted...

My car has a stock t25, 3" downpipe and cat back with no cat, evo 9 fuel pump and bypass valve, open intake, and running ceddymods flashed.

If I try punching the throttle at ~3500 RPMs or lower, I start seeing about 3-12 knocksum. It almost feels like the clutch slipping because the car feels like it just looses its breath. If I ease into full throttle, everything is perfectly fine all the way to redline.

just wondering if this was every figured out.

 

[911gdsmboostin]

Seems alot of us have a similar issue, with no definite resulting problem. Im sure the motor isnt really knocling much maybe a slight bit but not even in boost in my opinion is phantom knock. I get 2.8-8.5 at varrious times at low rpm in a good 3rd gr pull i see less then 3 the entire time which i can chalk up to my intercooler set up being my dump tube dumps just about ontop of my lower ic piping. But even at that its only at certin times i get a light for it. My light set for 3d plus.. everythinga new uofront noting rattling unless the sound of an o2 dump is causing problems. If anyone has found anything they though causing the problem pls repost. Im sure it will help point others in a direction to look. Dofferant things to try. Im okay woth the amount insee its just annoying at times when it knocks a few degrees out when you dont want it to.. i should be able to run more then 12 degrees in my set up and if i do i start seeing it and i think 11.0 afr is a little rich for me. I was abot to run 12.0 at one time. Not sure what changed but somthing did. Anyimput or advise helps everyone. Thanks guys