getting rid of engine knock

[black_shadow_18]

This winter I rebuild my DSM's motor:

Weisco 8.3:1 pistons
Eagle Rods
Balanced crank
removed balance shafts
EVO 3 Big 16G
Evo 3 manifold
GM 3" MAF and translator
FIC 650cc injectors
Walbro 255HP LPH pump
NGK BR7ES plugs / Accel 300+ wires
NEW 02 and Knock sensors


I am having a problem tuning out knock. The only way I can get it under control is to get it running SOOO lean the car hardly runs. If I add more fuel I get more knock. Right Now I have it set so it runs well, but My knock spikes at any RPM over 5000. When the car is cold I have VERY LITTLE (less than 3) knock, but when it warms up I get knock in the higher RPM ranges.

Any ideas? I posted this on club DSM but I get no help, so I thought I'd turn to you guys. Any help would be appreciated. Thanks

C.J.

I am running 91 octane fuel, 40 PSi base fuel pressure,

[SwitchBlade]

Have you tried running higher octane or an octane booster? Are you running the stock ECU? You might be able to tune it better with a different EMS.

[rage2]

How much boost are you running?

[black_shadow_18]

I havent tried octane booster, I figured the 2G DSM's run 8.5:1 compression on premium, so I should have been fine. I'm running the stock ECU and adjusting with the MAF-t. I think my problem is the maf doesnt adjust very accurately. I am only running 10psi (as low as I can). I have just spent the last hour tinkering, and have the knock under control till 4th and 5th gear and it spikes to about 30-33. And if i raise the boost to even 12psi the knock is 40+ in all gears. Let me know what you think and if you need more info.

Thanks

[hjr]

could it be as simple as your timing is advanced too far?

[SwitchBlade]

Never thought of that one

[black_shadow_18]

I have the base timing set stock at 5*BTDC. I was actually thinking of retarding it a few degrees. When I am WOT I get advance of about 22-25*. Too much?

[EK 2.0]

What settings did you set the Translator at??...

and man there has to be something wrong somewhere to be getting that much knock on that low of a boost setting, are you sure the "new" sensor is reading within spec??

Cause sometimes even though parts are new, they dont always work you know what I mean??

[black_shadow_18]

Right now I have the translator set at:

Base: 6
Idle: 2
Mid: -1
High: -2

And that has the knock lower (like under 15) but when the car is cold it just doesnt want to run on those settings, like it is too lean
Although the knock is low with these settings, my O2 voltages are REALLY lean (.01V when WOT), up until 5000RPM, then .85V to redline. But my problem knock is 5000RPM+. Its like the car wants to run REALLY lean.

[SwitchBlade]

Why dont you take it to a dyno and tune it there? Otherwise all i can suggest is get bigger and louder speakers > Good luck man. Let us know what the problem was.

[black_shadow_18]

Cuz theres no AWD dyno's in Calgary

[EK 2.0]

I hate to say it, but you might need to pick an an AFC man...I think its the fine adjustments between what the translator can do is where your problems lie man...

[black_shadow_18]

that has been my thought as well, but am stuck between cheaping out and going for a used version 1, or getting the way more "finetuneable" version 2..

[efnot]

i had this problem for my 22r in my celica, my rod bearing on piston 2 wasnt seated properly, knock was loud tho, could definately tell there was something wrong

[black_shadow_18]

I cant here anything tho, just my datalogger is telling me there is knock. Ive decided that my intercooler is getting heat soaked, and letting too hot of air in the engine. Thanks for everybodies opinions and suggestions.

[heavyD]

Do have an adjustable fuel pressure regulator to go with that 255 lph fuel pump?

[black_shadow_18]

nope

[heavyD]

Originally posted by black_shadow_18
nope

You absolutely need one to properly tune your air/fuel mixture. A 255lph fuel pump will overrun the stock fuel pressure regulator. The stock regulator cannot return the fuel to the fuel return line fast enough to maintain a constant pressure. This causes a non-linear fuel pressure condition all over the air/fuel map. It is really a must especially with larger injectors.