STX Rules and Setup Questions

[tigermack]

Try using higher octane?

[tahdizzle]

Originally Posted by tigermack

Try using higher octane?

In 2015 i heard that e85 is a no go in STX.

Have you heard anything like that?

[Wepeel]

Originally Posted by tahdizzle

In 2015 i heard that e85 is a no go in STX.

Have you heard anything like that?

It's already a no-go in STX.

[Wepeel]

Originally Posted by jprice130

I've been experimenting with an STX tune for my FR-S using RomRaider/ECUFlash/Tactrix and have noticed that data logs of my AutoX runs produces quite a bit of engine knock which of course pulls timing and reduces my IAM.

This is quite frustrating, because I've done numerous dyno pulls and straight road pulls in 2nd/3rd/4th gears and NEVER get knock in these conditions. The tune makes more power and torque, but it's annoying that all my work on the tune gets undone by knock events that pull timing during my AutoX runs.

Are all the abrupt braking, steering, and acceleration inputs of a typcial AutoX course causing false knock and this is just going to be a fact of life? Anyone else out there on an aftermarket tune get the same kind of knock events when you review datalogs of your runs?

Are the knocks mostly noticed in the abrupt throttle on transitions?

[jprice130]

Originally Posted by tigermack

Try using higher octane?

Yep, for my last event, I ran my tank down empty and put in 2 gallons of 100 Octance gas (even though I'm tuned on 93 octane). Still knocked while on course. Never knocks going WOT in straight lines whether I use 93 octane or 100 octane.

[jprice130]

Originally Posted by Wepeel

Are the knocks mostly noticed in the abrupt throttle on transitions?

It definitely happens on initial throttle application, but even when I'm on the gas for longer and am acclerating, I get numerous knock events. When looking at data logs of acceleration it's hard to remember exactly what I was doing on course though. Like, I might be constantly acclerating but also transitioning the car through offsets or slaloms. I obviously wouldn't be doing that when on a dyno or doing a WOT road pull.

The other thing is that there isn't a particular RPM range that is problematic. There's a little bit of knock everywhere between 3500 and 7500 (I raised the rev-limiter a little from stock).

[BRZZZZZZZZZZ]

Fuel starvation maybe?

[jprice130]

Originally Posted by BRZZZZZZZZZZ

Fuel starvation maybe?

I haven't noticed any fuel starvation during my runs, but I did think about running a little more in the tank next time. I usually run near empty (just before the gas light is on), so thanks for that suggestion. It's certainly worth a shot.

[Kido1986]

These cars have been noted as running really well when low on fuel so I'd be interested to see if that is the case.

I'm curious if it is to due with temperatures. Specifically oil temperature. Excuse my ignorance in tuning but doesn't the ECU have the ability to pull timing to create less power when oil temps are up? Outdoors on a hot day, on boiling pavement/concrete, I'd bet it's much hotter than dyno pulls. Coolant and EGR temps too but primarily oil focused as these cars get stupid warm oil temps without a cooler.

[Simmons]

Originally Posted by jprice130

I haven't noticed any fuel starvation during my runs, but I did think about running a little more in the tank next time. I usually run near empty (just before the gas light is on), so thanks for that suggestion. It's certainly worth a shot.

These cars Do Not fuel starve....Last week we ran the car really low so we could switch to 100 octane. The needle was lower then I ever saw it before and no problems.




Simmons

[Kido1986]

I was WOT on the highway one day, moments before I ran out of gas. Not my proudest moment but someone had to pass that b hogging the left lane.

Point is, it pulled well to the redline.

[tahdizzle]

Rule No. 1 in Dizzle's book: Performance Driving on a Budget:

1. Be faster than the needle

[jprice130]

Originally Posted by Kido1986

I'm curious if it is to due with temperatures. Specifically oil temperature. Excuse my ignorance in tuning but doesn't the ECU have the ability to pull timing to create less power when oil temps are up? Outdoors on a hot day, on boiling pavement/concrete, I'd bet it's much hotter than dyno pulls. Coolant and EGR temps too but primarily oil focused as these cars get stupid warm oil temps without a cooler.

You're right, the ECU does have timing compensation tables for high temps. The only ones I'm aware of pull timing for high intake and coolant temps (although the stock tune has all 0's in the coolant compensation table). I haven't seen any compensation tables for oil or exhaust temps. Either way, I'm okay with how the stock tune accounts for intake temps and I didn't change those tables.

With that said, even with the temperature compensation tables pulling timing, the engine may still be susceptible to knock at high temps, so I'll definitely compare my data logs more closely to see how the temps of my AutoX runs compare to the temps of my dyno pulls and road pulls. Thanks for pointing that out.

[Wepeel]

Originally Posted by jprice130

You're right, the ECU does have timing compensation tables for high temps. The only ones I'm aware of pull timing for high intake and coolant temps (although the stock tune has all 0's in the coolant compensation table). I haven't seen any compensation tables for oil or exhaust temps. Either way, I'm okay with how the stock tune accounts for intake temps and I didn't change those tables.

With that said, even with the temperature compensation tables pulling timing, the engine may still be susceptible to knock at high temps, so I'll definitely compare my data logs more closely to see how the temps of my AutoX runs compare to the temps of my dyno pulls and road pulls. Thanks for pointing that out.

I've seen oil temps around 220-230 on a hot day during autocross, not a whole lot hotter than what you'd see on the highway, and nowhere near what you would see on a track (not sure if they pull timing either).

Have you had a chance to log the stock tune to see if it behaves the same way during an autocross run? I know in my STI the normal road log (pull from 2000 to redline) rarely showed any knock events but during my autocross runs I'd get -1.4 and -2.8's popping up, FBKC and FLKC, and really nasty stuff bouncing the limiter (up to 8 degrees of correction). Never saw IAM drop though.