C5kid

iTrader: (12)

Figured I would ask this over here since I know alot of you guys do your own tuning.

First pull was low, but I figured I would have some tweaking to do anyway.

It was 11.1-11.4 on the AFR so I cleaned that up and got it to 11.7.

Here is the problem, I am getting CRAZY knock and have no clue why. My fuel pressure was staying good @ 58psi my injectors are only goin up to 80% duty cycle, my IATS were in the 63-64* range.

What is goin ON!!!

I am really stumped, and I know its not bad gas cause I was out earlier logged the car alittle and there was no knock.

I have had this problem in the past and could never get it sorted out, hopefully someone on here can give some advice.

Attached is the dyno run and my current tune.

Yes in the tune I have 18* of time WOT, but on the dyno using the RTT i had it down to 12* and was still getting knock.

pulled the plugs, nice tan color, no black specs.

No oil in the intake, headers are not hitting anywhere on the chassis to cause false knock.

Right now I just have the PVC venting to the atom, so there shouldn't be any crank case pressure.

OUTLAWZ RACING

iTrader: (9)

Are the knock sensors new or in good shape?

code4

iTrader: (30)

Have you ruled out burst knock & are you sure you don't have some bad fuel.

C5kid

iTrader: (12)

Knock sensors are the stock ones, so they could be shot.

Here is the other thing, I rolled into the throttle on the street when I checked for knock. On the dyno I would just mash her to 100% throttle.

If I roll into the throttle, no knock, mash the throttle & I get the knock.

OUTLAWZ RACING

iTrader: (9)

Are u certin the headers arent rubbing the car. At wot the motor tends to tq itself on non solid motor mounts. And if u installed the intake I would recheck the line to the knock sensors. They can easyly be pinch by the intake.

C5kid

iTrader: (12)

There are some tight spots between the headers and the motor, but I can yank really hard and they wont come close to hitting.

I also have poly motor mounts so the motor doesn't shift around that much.

I am goin to pull the intake off and check the wires and knock sensors I guess.

lmt0705

iTrader: (7)

sounds like false knock to me

dimetweaker

iTrader: (1)

I have a question, and it might be a stupid one since im working on my first FI build ever... but you said the fuel pressure was staying good at 58 psi; shouldnt that be climbing with boost? im guessing it goes along with injector duty cycle too somehow but I figured id ask

code4

iTrader: (30)

Sounds like burst knock. If this is what is happening it will decay pretty quick. There are some adjustments you can make on your tune.

ChiTownHustler

iTrader: (3)

This is burst knock you are describing. It pulls timing for very fast throttle transitions to ward off knock

C5kid

iTrader: (12)

Got it fixed guys!!!

So I have been messing around each night, pulled the knock senors out, no rust clean... So I changed my plugs to be safe (NGK TR6's).

BlownBlueZ06 sent me a timing table but it was a dog (sorry, i lost all my throttle response).

So what I did do is, copy the cells from .88 g/sec down and 2400rpm over (this is where I was getting the knock) from BlownBlue and pasted them into my table.

BAMM!!! no knock, I even added alittle bit of timing now I am running 14* advance and she has nothing, not even a blip. So what I THINK was the problem was I had to aggressive a a timing curve goin into boost and once it started pre-detenating, it couldn't stop.

mean94lt1

iTrader: (34)

good to hear ya got it figured out

98Z28CobraKiller

iTrader: (17)

A car with a stock regulator in the tank will (should) not vary fuel pressure. Boost reference fuel pressure is done with an aftermarket regulator and the vacuum nipple attached to manifold pressure.

OP. Glad you got it worked out.