knock sum issues.

[Silent2g]

alright, this keeps messing with me learning curve of things, or should i say. how they should work

lets go back wards from 5th gear at 15.5-16 psi

92 octane

base timing at 7 {reads 9 at 1000 rpms}

stand on it, 15 psi. knock knock all the way up to 5k or so rpms

4th gear, 3k rpms 15 psi.
no knock all the way to 6k

3rd gear {here is were it gets funky}
15 psi, starting at 3k rpms
stand on it, no knock UNTILL 5500 rpms, then it jumps to 7-9 counts

second gear 15 psi
3k rpms 15 psi
lay it out, knock is 0-1 till 5500 rpms. then jumps to 10 then back down to 5, then back up to 7.


now, knowing the car is more then likely running lean up top is what im gathering from the datlog runs. but why wouldn't it knock at 120 mph where there is a lot more of a load on the motor. longer times at those rpms then second or third gear???

timing advance is 17 degrees at WOT.

i have also noticed if i ease into it i don't get any knock. but if i drop a gear and get on it hard and fast the knock sky rockets.

ecu not catching up fast enough to cope with this sudden change?
or is it another lean factor.

if you need a mods list i can post it.

duty cycle is around 54 %
o2 voltage is somewhere around 70-75
92 octane
42 degrees outside

 

[jdmawd]

1) make sure you have good plugs and wires(change the plugs just to be safe)

2) dont use the logger to determine base timing get a timing light and do it the right way try 5*

make no other changes, and log again see if that helps.

 

[Silent2g]

ngk wires
stock plugs
guess it could be time for new wires. im not in the mood to spend 100 bucks on magnecores

guess i can try it later in the week, or next weekend
the local people on the dsm list are saying mas over run
i don't think thats the case. but i could be wrong.
who knows

 

[NJGSX96]

Is the MAS untouched? What does the logger show as far as airflow?
What injectors and do you have any fuel control?

Knock past 5500... you're lean up top. You need to add more fuel.

"i have also noticed if i ease into it i don't get any knock. but if i drop a gear and get on it hard and fast the knock sky rockets"

That is the way it is. Guess here, but I think it has to do with that initial squirt of fuel. Easing into it, it is already getting some fuel and going from there. Stomping on it goes from nothing to everything. Can't do it. VPC respone knob helps that (if you got a VPC). At least that has helped me out, which is what I base my assumption on.

 

[Silent2g]

Originally posted by NJGSX96
Is the MAS untouched? What does the logger show as far as airflow?
What injectors and do you have any fuel control?

Knock past 5500... you're lean up top. You need to add more fuel.

"i have also noticed if i ease into it i don't get any knock. but if i drop a gear and get on it hard and fast the knock sky rockets"

That is the way it is. Guess here, but I think it has to do with that initial squirt of fuel. Easing into it, it is already getting some fuel and going from there. Stomping on it goes from nothing to everything. Can't do it. VPC respone knob helps that (if you got a VPC). At least that has helped me out, which is what I base my assumption on.

510 injectors
stock pump w/ rewire
removed screen and silencer is the only mas air mods thus far

i think its time for me to get a bigger pump

but for some reason, this doesn't explain why i can go full tilt in 4th gear at 16 psi and have a zero knock sum. but can't do it int he lower gears.

im cornfused

 

[Kevin Jewer]

If the lower gears run out REAL fast then the ECU doesnt alway ahve time to fully advance timing. But this is the opposite of your issue and found on 350+ wHP cars. I wouldnt suspect anything in the eCU programming.

One thing I have noticed now that I have a "good" logger is that airflow is higher in the lower gears. And since fuel is injected per airflow you might assume you would run out of fuel sooner in the lower gears than in the later gears. Load is high in higher gears, But at WOT fuel is injected based on airflow. IF you are maxing out your fuel setup I wold suspect it'd be worse in the lower gears based on what I have logged for airflow. In my case the difference can be up to 2lbs per minute frm second to third at the same rpm. Might be time for a pump

 

[Rodman]

Not to mention the intercooler is working better at 120 VS. 30 mph. The faster you go the better the intercooler works

 

[Silent2g]

i've got it figured out now
mas over run
o2 voltage is between .88-.90
Hz is pegged at 1606
knock sum is zero at 16 psi on pump gas