unusual phantom knock and other problems.

[FirstYearTalon]

so lately my talon has taken to running like pure crap for several reasons.
#1 phantom knock: any time i touch the gas below 3150 rpms it shoots up to 43 counts instantly. I know the usual causes of pk, but I have a new knock sensor, rebuilt head with 3g lifters and poly motor mounts. now above 3150 rpms, I get no knock EVER. part throttle or wot, it drives great, as long as i stay above 3150. I have the knock gauge conversion so I know. every time i cross that rpm everything goes good. it makes the car almost impossible to drive.
#2 boost cycling, not sure what is going on here, but it sounds like my bov is opening when it should not be. now this only happens when it's doing it's phantom knock thing. but it makes the car surge violently and if i'm at low speeds it will sometimes stall. When it does stall it won't start up again right away, it just kindof lopes and I have to hold my foot 3/4 of the way down till it comes out of it.

I'm almost sure these problems are RELATED.

yes i did a boost leak test
mods in profile.

 

[andymoraitis]

I'd re-check the torque on the knock sensor to make sure it's at 17 ft/lbs and also pull the ECU to smell for leaking caps (a rotten egg smell). It almost sounds like it's ECU related since your problems diminish when you go into open loop.

Try that and let us know what you find,

Andy

 

[FirstYearTalon]

knock sensor is torqued properly, and new caps in the ecu, but I am going to try a different one today because I agree that it seems computerish

 

[andymoraitis]

I'd be interested to know your results when you swap the ECU. I really hope that does it and solves the problem.

Good luck and I'll follow up after you post again.

 

[adidalax]

couldn't a bad O2 sensor cause something like that?

 

[DJ23GSX]

Have you solved this problem yet? I have almost the same issue where any throttle under 3k knock goes crazy except mine goes away once the car is fully warmed up. I know i have one leaky cap and was wondering if you tried the other ecu yet?

 

[Gumba]

new ecu help?

 

[DJ23GSX]

new ecu help?

I got a keydiver eprom chip that ignores knock under 3k rpms I did try another stock ecu and it didn't help. Exhaust leaks have been known to trigger phantom knock.

 

[DarkMyrakul]

hey if you figure out the problem let me kno too i have the exact same problem or pm me so maybe we can figure something out. 43 counts of knock under 3150 and if you step on it it almost sounds like you have a huge hole in the piping somewhere.