Need some tuning help from some of you Professionals.

[Onefast99gsx]

It's been a while since i posted or even visited here. Been breaking the car in slowly since it has a new clutch and many other things. I've been tuning the car quite a bit over the last week with DSMLINK getting all my global and deadtimes within 1%. I've posted similarily on dsmlink without much good feedback so i thought i'd ask some of you that have way more experience than i do.

In every single log of mine i have knock and it's pulling back my timing. It's weird, it happens in almost the same spot everytime 5200rpm's. You could almost set your watch by it. It pulls back anywhere from 3 to 6 degrees(most commonly 3 to 5). It never happens in 1st gear at all period. It happens in the same spot though 2nd, 3rd and 4th gears. I've tried richening it, leaning it, i've pulled back a couple degrees of timing but all that does is just give me less knock. I just don't think i should have to pull back any timing for the current setup. Head was completely torn apart, ported, each and every lifter was cleaned thoroughly in a 2 step diesel process similar to factory manual method. Motor mounts are all new Protane mounts. The only thing i can say i discovered was a huge exhaust leak last night. The new gasket between the 02 housing and downpipe must have shit out or the downpipe loosened(haven't looked at it yet). I don't know if the loud noise from the leak could create some sort of harmonics that are interrupting the knock sensor? Fuel is 93 octane, boost is at 18.5psi.

Can any of you suggest anything to try or look at? I could really use some direction here.

Thank you!!

99GSX
PTE 50 trim, cut divider, internally gated
PTE 780 cc injectors
Magnus intake
HKS 272's
1g T.B.
Griffin FMIC 2.5" piping throughout
Walbro 255lph rewired
DSMLink
SouthBend DxD OFE Clutch
Fidanza Alum Flywheel
FP Intake pipe
Stage 1 ported head
Stock fuel rail, stock f.p. regulator
3" Exhaust
JAZ catch can
(2) 12" Mr Gasket 1400cfm each, fans
.... all the other supporting usual mods, etc..

[CDeutsch]

The ECU is bumping up your timing with the RPMs. Maybe when you hit 5200 it's too much. How much timing have you tried pulling? You could also try 100 octane and see if it goes away. At least then you'd know if it's real.

What happens if you slowly take it up to say 5500-6000 so you don't get knock and then go WOT? That might help rule out harmonics.

[Onefast99gsx]

I tried pulling -2 degrees all the way up from 5000 rpms on up. That's not alot but if i pull much more it will kill the power on top. On a 3rd gear pull, i really like to see 16 to 17 degrees of timing by the end of the gear. When i get this knock, i might get 13 degrees. I have 5 galls of B33 which is I believe 116 octane. I'll have to run the car more dry because she's got 3/4 tank right now. I'd be best to only have 3-5 gallons of 93 and then mix about 2 galls of B33. I guess the way energy is right now, ya gotta wonder if 93 octane is actually 93 octane at the pump. BP is where i've been getting my gas.

I could also try the slow test that you describe to doing. Rather than driving like at a race, i will ease it from 5k on up and see if easing it vs. beating it makes a difference. These are all certainly good things to try and i appreciate it. It's got me so frustrated because now i want to take it to the track. What's weird is why doesn't it do it in 1st gear at those r's? I guess because the fuel consumption is much greater in the higher gears even at the same rpms. That's my theory.

Thanks.

[95tsi]

Try turning the boost down and see if it still knocks. Might be able to run say 17psi with out knock vs. 18.5 with knock.

[TheBlizzard]

With your mods you should not be knocking at that boost with a 50trim. Like stated above, put some decent gas in your car and see if that helps. My guess from listening to your post is that you have some bad/low quality gas. If that doesn't help then run some logs and see where its knocking and play with fuel and timing in that spot and see if you can get it to go away.

CRAIG

[CDeutsch]

Just be sure to post the results if you fix it. ;) I'm interested because my 2G has similar mods. I'm having other issues, but latetly with the small amount of tuning I've been getting in I've been running about 22 psi on pump, but I have the timing retard 3 degrees starting at about 4000.

What compression pistons are you running?

[niterydr]

If you could post up a log, or better yet, send a log to my email, that would help in diagnosis the problem.
18.5psi on pump gas really isn't that much, granted the griffen fmic isn't the largest, but it should support the boost levels you are attempting to run.
If the ecu is pulling it back to 13 degrees, you must be knocking 10 counts or so? (I forgot what it reads on dsmlink, maybe 3?).
I would double check the gas scenerio, like mentioned.
Following that, I would obviously make sure baseline timing is at 5 degrees, and your not fighting an uphill battle against the ecu. Also, make sure nothing is 'happening at that time' aka harmonic interference (Chris mentioned a VERY good method to rule that out).
Finally, once again, try to post up a little more information to whats happening. Are you seeing a jump in airflow numbers? Injector duty cycle jump?
Keep us posted.
swanny09@yahoo.com if you want to send me a log.
Good luck.

Also, what is the motor setup exactly? (edit* see chris beat me to this).

[Onefast99gsx]

Thanks to all you that stepped in. Not only did you give me something to go on but I think all of it is very useful things to try. Tonight i can try everything above except for the fuel. I don't want add some B33 to 3/4 tank of 93 octane. I want to run the tank more dry. B33 is like $8.00/gall. Niterdyr- I will certainly send you log(s). To anyone else that don't have dsmlink, i will post the dsmlink data in text format to show you what the numbers are in a non-knock area vs. the knock area. I wouldn't expect a posting until later tonight. Gonna go fix the exhaust leak right now. I Gtech'd it last night and ran a 13.32 at 112.x mph. Counting the log seconds on dsmlink showed the e.t. to be pretty accurate. Speed realisticaly was about 105-106ish. I still have yet to learn how to launch a AWD as my r's got pulled way down in the 2k range and killed the 60foot, plus she was knocking pretty good 2nd, 3rd and 4th gears so i was back pedaling it a few times and only getting about 13 degrees of timing at the top of the current gear. I'm guessing at that boost, a good launch and getting rid of the knock, i'd be in the 12's consistantly. Something to look forward to. The power has yet to be unleashed.

Thanks much.

Will post later.....

[Onefast99gsx]

Just be sure to post the results if you fix it. ;) I'm interested because my 2G has similar mods. I'm having other issues, but latetly with the small amount of tuning I've been getting in I've been running about 22 psi on pump, but I have the timing retard 3 degrees starting at about 4000.

What compression pistons are you running?


CDeutsch- It's the stock 2g 99GSX motor, including the head. So, what's the compression ratio? 8.5:1 of the top of my head, I think the 2g's are.

[CDeutsch]

CDeutsch- It's the stock 2g 99GSX motor, including the head. So, what's the compression ratio? 8.5:1 of the top of my head, I think the 2g's are.

My bad. I thought you had a built 2.4 for some reason.