Weird ongoing knock issue

[bryanwheat]

Alright guys, i have been searching for another case of what i am going thru right now, but with no luck. This has been going on for months and i havn't been able to get a good tune on this car yet. I Don't ever have any problem tuning my cars that i have had before, or friends and customers cars, but this one is a fregin nightmare. I will start with my mod list.

Walbro 255
Aeromotive fpr (40 base fp, i have tried higher and lower)
Safc
680cc injectors
Turbo back 2.75 inch exhaust
Front mount
Ported 2g mani
ported 2g o2 housing
New knock sensor
compressoion within 10 percent in each cylinder
Bullseye to4-v trim @ 12 psi was at 15 but i dropped to get rid of knock
2g maf

Basically a good 374-400 horse setup, right.

Well I go to tune this thing, set my low trims, everything is good, i can make a pull at part throttle, no knock, no timing being pulled, pulls good, fuel trims at 100 percent. Now i go to tune my high and i get the fuel trims to 100 percent, and at around 4,500 and up like 20-46 counts of knock, so i do what anyone would do. Richen it up. I have the safc set to like -7 across the board just to get the knock down, but by the time i richen it up enough to get rid of knock it it too rick and bogs and sputters like a sob over 4,500. I have checked for bost leaks, and fixed all of them, new bpr7es plugs, good wires, no cel's, checked base timing, and it is right on, i am running good gas, shouldn't take over 93 for 12 psi. My fmic core is like 18x10x3, and isn't heatsoaking whatsoever, fuel pressure is steady. I have a possibly theory though. MY licp runs by the exhaust, but is more than 6 inches away, but i am possibly getting at that maybe the pipe is heatsoaking, and heating the shit out of the air. I have ran setups like this before with no problems what soever. This one is just killing me. I am ready to swap ecu's and try some durastic things. Also i know that it is not phanton knock, because i can hear the detonation. Any help would be great. I am out

 

[GVR4592]

Post some datalogs, that might help diagnose the problem. I would also check cam timing as well. What are your SAFC settings for fuel corrections? Is you maf hacked?

 

[zippyshoe]

When you go WOT, what is your front O2 sensor voltage doing? I know that using the factory O2 sensor is a poor means of tuning, but if it is not pegged at close to 1 volt at WOT, then this may point to a fuel delivery problem.

Also, you may be pushing the limits of safc when trying to tune-in those 680cc injectors. Perhaps the ECU is allowing too much timing advance when compensating for those injectors.

 

[donmagicjuan]

Unless you're sure that it's not, you could have an overtorqued knock sensor. They have a tendency to pick up the tiniest vibrations when overtightened. The spec on them is 14-18 ft-lbs. I'm not saying that's definitely your problem, but it wouldn't hurt to check, especially if you're having that much trouble getting rid of the knock at low boost.

 

[a1320eclipse]

If you think your pulling too much hot air, check the intercooler for a hot charge. what i mean is do a good hard 3rd gear pull and jump out and feel the inlet side of the intercooler, it should be warm, and feel towards the outlet side, if its still warm all the way across your ic isnt being very efecient. like with mine, on 18psi, the first 4 inches of the ic is warm, and the rest of it is cold as hell, and my ic is about 28"x16"x2.5". just a thought

 

[4G63 For Me]

You need to start logging some data to figure out what is going on. Do another boost leak test, check your coil pack (those tend to go out partially, only causing knock at certain speeds/RPM), recheck your plugs and wires.

 

[bryanwheat]

Post some datalogs, that might help diagnose the problem. I would also check cam timing as well. What are your SAFC settings for fuel corrections? Is you maf hacked?

Cam timing is perfect, i have been working on these things for years, i am fluent on setting cam timing. My safc is about -7 across the board right now, but is too rich, That is where it has to be to not knock. The maf is unhacked. I have had 4,500 rpm knock since i got the car, and i have changed everything possible, maf, tps, cas, coil pack, transistor, well pretty much everything but the ecu. IT won't go away, i am leaning towards the ecu. I an sure that it is not p/k i can hear the knock when my window is down. Always starting at 4.5k.

 

[Larry L]

Perhaps its rich knock. I'd re-torque the knock sensor, have the ECU checked out. There has to be a reason. I run the same set-up with the Holset HX-35 Turbo, and my AFC settings are in the -34 area at 18 psi, on 91 octane. O2 Voltage is always right around 1.0 at WOT, and I only trigger my knock light on rare occasion. I'm also going to re-torque my knock sensor because I believe I did tighten mine too tight. But my car pull like a bat out of hell all the time. Do you have any CEL's?