Race Gas

[laloosh]

Okay so im going to the track oct 3rd. As most of you know i upped the boost on my lil ms3 and the car is running great. Last night i ran a srt4 that today trapped a lil over 105mph. When we ran it was almost dead even with me pulling a tiny bit around the 120 mark. My guess is that i will be trapping at 105-106 with the added boost. Being that i raised the boost will i benafit from race gas at all. I still have a cat so im going to run unleaded 104 probably. Get there with about 1.5 galloons left and put 2 gallons in it. I have noway of monitoring timing with the upped boost. Im not sure if the car is pulling timing, but it flies right now. IM just not sure if the ecu on this picky car iwll actually realize its race gas and up the timing a lil. Any ideas/suggestions?

 

[BluMicaR]

Hmm, disconnect neg battery cable and reset ECU to make it realize? I reset last night second time after my Cobb SRI and it was cooler outside than it was the night I installed. I think it made a difference, I was spinning tires half throttle in first and second last night and this morning, and before that half throttle was my 'safe' way to get full boost with no spin.

 

[mazdaspeed32007]

every time you fill up it takes your car about a tank to re-set itself to the new gas. if you put in 87 it would take about 1-2 tanks for your ecu to reset itself. unless your 2 gallons of race gas can get you about 400 miles i would just try to reset the ecu with the battery terminal. thats probably your best bet. it will run better either way but if your ecu is "used to it" from the start i think you might be able to trick it for a little. sort of the same if you added a CAI and disconnected the ecu. your car would run leaner until the ecu caught up with it about 100 miles or so later. (my theory through logic anyway)

 

[BoostedSpd6]

ive run twice at the track both times using race gas...ive never run with just 93 or 94 so i cant say what to do... but i havent had a problem with the car as far as performance goes after using it.. it took 1 fillup to get the gas mileage back on track though as stated above.

 

[laloosh]

what are your mods to reach that 105 trap speed?

 

[SwampAss]

every time you fill up it takes your car about a tank to re-set itself to the new gas. if you put in 87 it would take about 1-2 tanks for your ecu to reset itself. unless your 2 gallons of race gas can get you about 400 miles i would just try to reset the ecu with the battery terminal. thats probably your best bet. it will run better either way but if your ecu is "used to it" from the start i think you might be able to trick it for a little. sort of the same if you added a CAI and disconnected the ecu. your car would run leaner until the ecu caught up with it about 100 miles or so later. (my theory through logic anyway)

Are you sure? It's my understanding it adjusts timing/boost on the fly. A lower octane gas would affect both. It's also my understanding that the ECU doesn't really learn anyway. There's a small degree of adaptation but this whole "ECU has to learn" thing is not exactly accurate.

 

[mazdaspeed32007]

Are you sure? It's my understanding it adjusts timing/boost on the fly. A lower octane gas would affect both. It's also my understanding that the ECU doesn't really learn anyway. There's a small degree of adaptation but this whole "ECU has to learn" thing is not exactly accurate.

the ecu must "learn" something because if it takes a tank of gas to have your car run "normal" again it must be your ecu adjusting to the changes that were made to the car. i understand what your saying but i believe its somewhere in the middle of both our assumptions/knowledge. thats why you feel immediate changes to the car but you also have a lasting effect before the car can return to normality.

 

[SwampAss]

In speaking with CPE and reading the installation and foreword with the Stand Back instructions, I got the understanding that the ECU doesn't learn.

 

[Abaddon]

In speaking with CPE and reading the installation and foreword with the Stand Back instructions, I got the understanding that the ECU doesn't learn.

From what I understand about ECUs in general, it might depend on what mode the car is in.

On my 96 Taurus SHO it worked like this.

WOT, open loop mode. ECU runs based on gathered data during non WOT time. Ie, the ECU "remembers", but doesn't really "learn". It just runs based on how it worked during normal operation.

Non WOT, closed loop mode. ECU tries to run based on what it "remembers" but actively changes everything based on what the sensors are telling it.

I have no clue if the Mazda ECU runs in the manner.

 

[dkswim]

yes it dose run in open and closed loop, in open loop it is trying to maintain an A/F ratio and maintaining that it gets a value based off of the stock map a corection figure and uses that then you have to start getting into short term and long term correction values and then you open a can of worms and call it all good. but to answer the real Q car will run better you ll have better detnation deterence but you shouldnt gain anything off of the gas unless you have a racegas map loaded up

 

[Jays07MS3]

yes it dose run in open and closed loop, in open loop it is trying to maintain an A/F ratio and maintaining that it gets a value based off of the stock map a corection figure and uses that then you have to start getting into short term and long term correction values and then you open a can of worms and call it all good. but to answer the real Q car will run better you ll have better detnation deterence but you shouldnt gain anything off of the gas unless you have a racegas map loaded up

I think you mean in closed loop mode the ECU tries to maintain an A/F ratio (stoich or 14.7). But in any case, if he uses race gas, he'll be able to turn up the boost a little more as long as his fuel pump spits out enough fuel to go with it. Even if the ECU doesn't advance the timing due to the race gas, higher boost should be ok since detonation won't occur as easily.

 

[mazdaspeed32007]

ECU tries to run based on what it "remembers" but actively changes everything based on what the sensors are telling it.

"remembers"....thats the word i was looking for. sorry swampass. wow...is that how it feels to type your name....swampass. lol. funny.

yea so back to my original thought....the ecu remembers....not "learn"