Knock from 2100 - 3000 rpms at <30% Throttle, Keydiver ECU

[RuBiCaNT5X]

I just put my Keydiver Stage 3 2G ECU with 680cc injector compensation and I have my SAFC2 in. For those of you who don't know, it turns the stock 2G boost gauge into a knock sensor reader. First hash on the gauge is 7 counts, 2nd hash is 14, 3rd is 21... After 5 counts, I had it set to have the CEL come on. I get wierd readings between 2100 - 3000 rpms. I've had my SAFC2 as low as -9 to as much as +3. The ECU with the injector compensation automatically corrects, regardless because my O2 trims with it running rich go to a -11, -13 at points. I have my Throttle points set at 30% for low and 65% for high. EGT's when cruising are around 1450 at about 15% - 20% TP. Anyway, randomly it seems, between that RPM range after I give it throttle (never exceeding 30%), I get knock and my EGT's go up to 1580+. After 3000, it goes off like a light. I don't have my high throttle set at all. I was talking with various folks about it and I found out that the BCS has a tendency to show what would be confused by knock to the ECU at around that RPM range. I also heard that the lifters will cause false knock. I can see those scenarios but why would EGT's be going up if it was false knock? I guess I am just looking for some insight. I appreciate it, fellas!

 

[RuBiCaNT5X]

BTW, boost is set at 15psi on my Ported Small 16G, read my profile for the rest of my mods...

 

[Enigma_Man]

Welcome to the world of phantom / part throttle knock

If the throttle is really low, chances are it's "phantom" knock, which means the knock sensor is more than likely just picking up random noise, interpreting it as knock, and the ECU doesn't know any better. No amount of changing fuel settings will fix this (unless you have some sort of fuel problem that is causing actual knock at real low throttle).

The reason why your EGTs go up, is because when the ECU sees knock, it retards the timing. The gasoline is ignited later in the cycle of the engine, and therefore more heat gets to your EGT sensor.

Look around this site for the term "phantom knock" for the various fixes people have had for it. It can be caused by many many things, and is a big DSM issue. The most common causes attributed to phantom knock are: noisy lifters, carbon buildup in the combustion chamber, loose engine mounts, etc etc.

I suffer from phantom knock, and I use the cans of silver "restore" stuff with my oil changes. It doesn't seem to help every case of PK, and it wears off after time, but it definitely helps mine out a lot, so I use it. The proof is in the results, so-to-speak.

-Jesse

Edit: Oh, some more info for ya. Phantom knock isn't "bad" in that it isn't harming your engine any. It's just going to make the ECU make the car slower, which is a bad effect, but it won't harm anything.

 

[RuBiCaNT5X]

Thanks Jesse, I am getting a new 1G head put on in a few weeks with the revised lifters so hopefully that is one cause right there. As for the engine restorer, I will probably have to do the Mopar CCC in a few weeks. Thanks again for the info, man!!

 

[44pirate]

I've got the keydiver also. My boost guage sits just above the first mark and doesn't move. Does yours sit, when idling, below the first mark?

 

[RuBiCaNT5X]

Originally posted by 44pirate
I've got the keydiver also. My boost guage sits just above the first mark and doesn't move. Does yours sit, when idling, below the first mark?

Mine works... It decently below the first notch, about 3mm below the first hash if I were to put a tape measure up against it...

 

[white 2g awd]

Originally posted by 44pirate
I've got the keydiver also. My boost guage sits just above the first mark and doesn't move. Does yours sit, when idling, below the first mark?

same thing with me, the only time i've seen mine go up above that, when i first put the ecu in, i let it re-learn, and i saw it go up a couple times, but thats it.

 

[doug]

Originally posted by RuBiCaNT5X
why would EGT's be going up if it was false knock?

Yeah, like Enigma said, the ECU doesn't know any better. It will retard timing when it receives knock info whether it's real or not.

Too bad you don't have DSMLink, or you could just disable the knock sensor below 3000 and 30% throttle (or whatever values you choose)....

 

[RuBiCaNT5X]

Originally posted by doug
Yeah, like Enigma said, the ECU doesn't know any better. It will retard timing when it receives knock info whether it's real or not.

Too bad you don't have DSMLink, or you could just disable the knock sensor below 3000 and 30% throttle (or whatever values you choose)....

That might be an option sometime down the road. I am leaning in that direction more and more every day. Once I get my timing belt serviced and get my 1G head on without lifter issues, I'll see if it's worth it or not. Thanks for all who replied!