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View Full Version : Need some tuning help from some of you Professionals.


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Onefast99gsx
06-16-2005, 11:27 PM
As i said i'd post... I'll post more specs and data sometime tommorow. I got other issues going on tonight non-car related. Pet is sick. :-( Did several tests tonight since my last post. First test was to run it on 19psi of boost just as i did yesterday. Knocked pretty good after 5200 r's just as its been doing.

Next test #2, I did the same boost level (19) but turned up the sliders in dsmlink from 4500rpms to 7500 to +8. Result: Knocked pretty good but not quite as much, probably 3.x degrees being pulled.

I checked the base timing then with the timing light. Dsmlink is nice because you can ground it just by clicking on a button on the computer. At about 750-800rpms, she was dancing right around 5 degrees BTDC. Correct me if i'm wrong. First time i did this. On a 2g, on the tbelt cover is the degree readout, the only number that is on there is a number 10. Then a couple of other lines and then what looks like a "T". I'm assuming that T means top dead. Well that's where the little white dot on the crank pulley was hovering around.

My next test #3, Put fuel sliders back to zero. Cranked boost back down to around 14.5psi. All be dammed! No knock in ANY gear. A couple times i had those little .4 degree phantoms but not all the time and hardly at all. Most of the time, it was knock free period. Ran this setup about 4 times with little to no knock.

What does this mean? The 93 octane i put in it the other day is shit? Not really 93 octane? With the refining troubles they're having, i really gotta wonder if we're pumping what its actually supposed to be. How watered down is gas nowdays? I'm gonna first switch to either Mobil or Citgo fuel. I expect the result to be the same though because i think all gas stations around here no matter the name get their gas from the same supplier. I have an alcohol injection unit that i took off the GST before i sold it. I need to get it on the GSX.

I'll post logs tommorow or something. I just got more important things than cars going on tonight. I just wanted to update you.

Good night.

TheBlizzard
06-17-2005, 12:23 AM
Like I said, sounded like bad gas to me. By lowering the boost you are lowering your dependency on gas quality and octane rating. Burn that shit out of there while running low boost and then put some decent gas in. Turn the boost back up to around 20psi and set fuel back to where it was and see if you are still knocking. My guess would be that you should be just fine once you have some better gas.

For example, when I get gas from down by where I work (Treasure Island Casino) my car always knocks if I run more than 15lbs of boost. Now if I get BP/AMOCO gas I can run 18-19lbs with no one hint of knock. With that shit gas from down by work I get like 13 counts in 3rd and 4th gear. Thats not a ton but I can definetly tell when I have a batch of bad/low quality gas. Just because it says 93 octane doesn't mean anything to me, its all where you get it from. And Amoco gas works the best in my car with race gas being the alternative.

Alpine TSi
06-17-2005, 12:04 PM
What kind of plugs are you running? With that setup you should be at a BPR7ES and gapped at 28 or so.

BTW +1 to Amoco/BP gas, I would knock like crazy on shitty gas, but with BP stuff I never had problems. Also eventhough Holiday offers 93 octane, don't get it.

TheBlizzard
06-17-2005, 12:28 PM
Fuck Holiday gas. Its not as bad as Super America but damn close. It will work if you don't run more than 15lbs but anything over that and its knock city on your car.

dsm10sec
06-17-2005, 01:12 PM
It's because MOST BPs use UNOXYGENATED, most other places use ethanol. If you register on www.mnsubaru.com they have a listing of 66 non-oxy places throughout the metro.

LightningGSX
06-17-2005, 06:42 PM
It's because MOST BPs use UNOXYGENATED, most other places use ethanol. If you register on www.mnsubaru.com they have a listing of 66 non-oxy places throughout the metro.
Oxygenated gas is better, ethanol reduces your chances of knock

Jakey
06-17-2005, 06:46 PM
Oxygenated gas is better, ethanol reduces your chances of knock

Thank you.

desolate
06-17-2005, 07:03 PM
I have to agree with the shitty gas around here. Everywhere you go pump 92+ octane it feels like 90 octane or less. You have to richen the shit out of your tune for a knock free run. Then you get weak power. I've tried Amocco, Holiday, SA, whatever. They all feel the same. If I am out for a little weekend throttle I just get 110 and call it a day.

CDeutsch
06-17-2005, 07:24 PM
But what if you fuel system is at it's limits? Oxygenated gas causes your fuel system to add more fuel correct? In that case you'd end up running lean, right?

dsm10sec
06-18-2005, 01:24 PM
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