Real bad Knock problem!

[JayRolla]

Ok I have been having issues with adding way to much fuel to get rid of knock.

Setup
Rebuilt 6 bolt, 1g rods, 2g pistons
2gmaf
safc
550cc rc injectors
3000gt fuel pump
16g

With that same setup and no fuel pump I had to have about +20% hi settings to get rid of knock at 11psi. I tried to tune out 15psi but seemed like I was out of fuel. I then installed a fuel pump because everyone said that was my problem. I had to take out a very little in lo throttle to keep fuel trims in line which makes sense since the pump added some fuel.

But in the high rpms I didnt have to change anything. I bumped boost to 15psi and started at +10% on high's. I had to raise hi throttle to about +30% fuel and it got rid of knock. I still had the fuel but I have to add so much. This cant be right.

Timing is at 5*btdc and most boost leaks are fixed, I know I have some small ones but not big enough to effect the fuel curve this much.

Before at 11psi I would get a missfire at about 6krpm's now it hits way lower around 5500rpm. I guess im blowing out the spark. Im running 6es plugs at .028 and have lowered them to .022 with no change on the blow out.

At 15psi and 7 counts of knock she pulls way harder but seems to be missing a little almost what timing pull feels like when its really bad then it missfires like fuel cut. Im not pushing enough air through the 2gmaf to hit fuel cut.

If anyone has any insight let me know. When I was in the middle of tuning my clutch gave so my car is down and out for a minute and want to replace anything I can now.

 

[spyderturbo007]

Wow, something isn't right if you have to add that much fuel. The 2g MAS should compensate for the 550's, so you should be pulling a little fuel to offset the pig rich factory AFR.

Have you check your fuel pressure?

 

[2002SL1]

Sounds like your knock sencer might be back. You should have that much knock at 11psi unless you have like no fuel going into the motor. Check the Sencer and see if it might be bad.

 

[JayRolla]

Knock sensor is new. Im going to check the FP. I was thinking of swapping the FPR with a N/T one and see if it helps. I was told they do raise with boost and it will raise my FP. My FPR may not be working.

 

[2002SL1]

Yeah if the knock sensor is new the defentally check the Fuel Pressure.

 

[JayRolla]

This is now only some of my worries, I just pulled the tranny because I thought my TOB failed but the clutch unit seems fine. Now im scared I need a tranny.

 

[JayRolla]

It was actually the friction plate that died. So im doing that today and going to put on another FPR to see if it helps. If not does anyone else no why I need so much fuel.

 

[lenhof13]

do you have a palm pilot /logger to see your 02 trim? i have the same setup but i have a 255 and my settings are at +5 to +9. Im not shure if the 3000 pump is bigger than a 255. But at 20psi it holds 100 on the 02 trim if you dont have a datalogger your in the dark

 

[JayRolla]

Im not dumb I have a logger. How do you think im seeing my knock. All trims as of last time I was tuning where between 100-105%. O2 reads around .94 I think at wot and does cylce at crusing and idle.

 

[scottsee]

Sounds like your misfire and your fuel problem may be two seprate issues. Does your Missfire go away at all with diffrent fuel enrichments?

 

[JayRolla]

No it does not Im thinking the misfire is something different. Ive swapped a used coil pack and transistor, along with new ngk plugs and msd wires. Its not as bad when its warm out at 11psi. But at 15psi it has a huge cutout at 5500-6500rpms. And has a slight hesitation all the way up likes its barely missing.

 

[scottsee]

Have you checked for carbon deposits in your sparkplug wires?

 

[delta448]

Jay,
-Just a thought, I know you probably already thought of this but maybe a clogged fuel filter or a pinched fuel line?
Have you checked the pump wiring or done a re-wire, any chance of an issue there?
Also, has the 2G MAF been hacked or is there any chance you are somehow getting unmetered air into the turbo?

 

[JayRolla]

The intake fits nice so I dont think im getting in umetered air. Maf is stock and ive tried two different ones. Im going to do a rewire here real soon. I checked the fuel line and from what I can see its fine. Fuel filter has been replaced twice in the last 6 months.

 

[JayRolla]

Well Ive noticed I need to add about +30% right when boost hits. Then after that I can lean out at about +20%. Doesnt this sound like fuel pressure is not raising with boost??

I notice I can go out start the car and do a run. Get about 7-14 counts right at 3400-4000rpm. Next run can have 0 knock. Its like I get the fuel sometimes and then others I dont. Its not pk because if I do add fuel it will go down as long as its still knocking.

Im swapping out my stock FPR with another one to see if that helps along with a new fuel filter even though its only about 10k miles old.

Now my question is what else could cause this. Pump has been checked, but not rewired. Lines dont seem to be kinked. Could it be my used 550cc injectors I got off ebay? I think I had this problem even with the stockers. I could not run any boost past 9psi on stock fuel system without knock.

 

[srumel]

hmm, it could be that along with your fuel adjustments, you're lowering the timing along with increasing the fuel thus cutting back (a little) on the agressive timing maps you are running on your stock? ecu supressing the knock a little. 8.5:1 pistons were not designed to run on such an agressive timing curve. i'm in the same boat you are by the way. need me an eprom!!