Fuse Pull: Low Octane Fuel Fix For L99 and LS3. Reset Fuel Map for High Octane Fuel.

[GTAHVIT]

updates?

[Nobama]

Thanks for the info. I'm going to try it tonight. I just got my car last Monday and I've put 2-3/4 tanks of gas and onlt driven 607 miles. That comes out to around 12 miles per gallon!!!! Just normal everyday driving.

[BamaCommando]

I got wind of the octane issue with the gasoline the day before my car got to the dealership and advised the dealer to fill it with premium or else don't add any at all. I was dealing with an old high school buddy and he assured me that GM reimbursed them for the fillup and that it didn't matter to the dealer if it was premium or not and that he would fill it with premium when it got in. I have only put 93 octane in it and it has about 1500 miles on it now. I went out with Mrs. BC yesterday with a stop watch and after several runs, we were consistant with about 6.1 or 6.2 zero to 60 times. I pulled the fuses and last night we went back out. The first run we hit 5.5 so I know we got a boost. We did a few more just to make sure and the best was a 5.2. I would suggest that everyone with the L99 pull the fuses and reset the ECM. It DOES make a difference.

[ls2gto]

Originally Posted by irpq11

I'm so confused.


Anyway, I was told that the fuel tables were automaticaly adjusting only one way. That it would adjust from high to low to protect the system but not from low to high. You can run high octane through the low tabled setting just fine but running low fuel through a high tabled system could damage your system.

Make sense?

It makes sense that your computer was behaving that way but that is precisely what is wrong. It does not make sense to even waste time with 2 octane tables if the engine cannot adapt in both directions between the 2. I do not own a Camaro but doesn't your owner's manual say you can run regular gas but that the engine will perform better on premium? That's what the quick reference guide for my G8GT says. If the first time you run 87, you end up forever stuck on the low octane table, then running premium will not do anything. For some reason, your "knock learn factor" is not returning to zero over time, even though no knock has been detected recently.

HPTuners knows this stuff better than most people and in case you missed it in my previous post, here is what they say right in the help section of their software that I purchased:

Main Spark Tables
The VCM constantly looks up both High Octane and Low Octane spark tables and interpolates a value between the two tables based on the current Knock Learn factor. If the engine has been operating for a moderate time without any Knock Retard then Knock Learn is zero and the interpolation favors the High Octane table, if Knock has been detected then the interpolation will move towards the Low Octane table. During MAF failure the Knock Learn is set to maximum and the Low Octane table is used (HP Tuners speed density enhancements allow both spark tables to function).


Note: Excessive spark advance will cause knock (detonation, pinging) and lead to severe engine damage. Do NOT rely on knock sensors as the only source of detecting knock during tuning.

I note that if your MAF (Mass Air Flow) sensor goes bad, the system defaults to the low octane table, but I would assume they ruled that out as being the problem.

[radz28]

Originally Posted by Dakota Kid

I am pretty sure my L99 is "healthy" but just for shits and grins I'm yankin' the 5 and 20.

Maybe we should rename the thread: "The 5 and 20 Mod'"

Originally Posted by GTAHVIT

updates?

[ls2gto]

PS

I hate to bring this up but the fact that the computer slowly adapts to various inputs over time makes me wonder if inputs that are not octane related are part of the problem. As in, will the problem slowly come back....

Yeah I know, I need to shut up and go back to the G8 board.

[PQ]

Originally Posted by ls2gto

It makes sense that your computer was behaving that way but that is precisely what is wrong. It does not make sense to even waste time with 2 octane tables if the engine cannot adapt in both directions between the 2. I do not own a Camaro but doesn't your owner's manual say you can run regular gas but that the engine will perform better on premium? That's what the quick reference guide for my G8GT says. If the first time you run 87, you end up forever stuck on the low octane table, then running premium will not do anything. For some reason, your "knock learn factor" is not returning to zero over time, even though no knock has been detected recently.

HPTuners knows this stuff better than most people and in case you missed it in my previous post, here is what they say right in the help section of their software that I purchased:

Main Spark Tables
The VCM constantly looks up both High Octane and Low Octane spark tables and interpolates a value between the two tables based on the current Knock Learn factor. If the engine has been operating for a moderate time without any Knock Retard then Knock Learn is zero and the interpolation favors the High Octane table, if Knock has been detected then the interpolation will move towards the Low Octane table. During MAF failure the Knock Learn is set to maximum and the Low Octane table is used (HP Tuners speed density enhancements allow both spark tables to function).


Note: Excessive spark advance will cause knock (detonation, pinging) and lead to severe engine damage. Do NOT rely on knock sensors as the only source of detecting knock during tuning.

I note that if your MAF (Mass Air Flow) sensor goes bad, the system defaults to the low octane table, but I would assume they ruled that out as being the problem.

Hmmmmm. Well, when I say 'I was told', I'm talking about my dealers service manager who called me. She said that it was the TAC person from GM who called her about my car. (as I said, I had someone kind enough to look into it further for me) She was told by him that it was a one way deal without the dealer reseting it.

So, then, if it's is supposed to adjust both ways, GM will surely 'fix' it and update it.

BUT, look how many people on here that have benefited from the reset AND NEVER KNEW THERE WAS A PROBLEM WITH THEIR CAR. A few of us suspected this all along. Despite many thinking we were crazy. So if GM wanted to they could just leave it the way it is and instruct the dealers to 'fix' (reset) them should owners bring their cars in with 'slow' complaints. I think most people would never even know.

[PQ]

Originally Posted by radz282003

Maybe we should rename the thread: "The 5 and 20 Mod'"

I was reluctant to advocate this as a stickey because I was asked to not 'expeirement' with the car any further. Of course when my dealer called me and told me that essentialy what I did was what GM told them to do with it, I thought the stickey was a great idea.

Originally Posted by ls2gto

PS

I hate to bring this up but the fact that the computer slowly adapts to various inputs over time makes me wonder if inputs that are not octane related are part of the problem. As in, will the problem slowly come back....

Yeah I know, I need to shut up and go back to the G8 board.

No, you're fine. It's a concern of mine too. I did more tests lastnight and got a 4.99 0-60. and another 13.3 quarter mile.

I'm gonna keep a close eye on it and in a month I'll reset it just for gp to see what happens.

[TJTKSDMJ8]

I did it last night....Pulled fuses...left it overnight....


did it work?







HELL YES IT WORKED!!!!!!!

[radz28]

Originally Posted by ls2gto

PS

I hate to bring this up but the fact that the computer slowly adapts to various inputs over time makes me wonder if inputs that are not octane related are part of the problem. As in, will the problem slowly come back....

Yeah I know, I need to shut up and go back to the G8 board.

I've been thinking about this too; I guess we'll all find out. I suppose, as long as GM is working on this, this simple procedure isn't too big a deal to do once-and-a-while.

IMHO - I've learned a lot from the G8 boards too, and if you contribute like this here, please don't go. I think we could all benefit from one another

Originally Posted by irpq11

I was reluctant to advocate this as a stickey because I was asked to not 'expeirement' with the car any further. Of course when my dealer called me and told me that essentialy what I did was what GM told them to do with it, I thought the stickey was a great idea.

No, you're fine. It's a concern of mine too. I did more tests lastnight and got a 4.99 0-60. and another 13.3 quarter mile.

I'm gonna keep a close eye on it and in a month I'll reset it just for gp to see what happens.

I hear you. I feel better after reading this post because I'd hate to be one to contribute to a problem for the owners who performed this on their cars. Use at your own discretion doesn't make me feel disconnected from any, at least moral, responsibility if something were to have gone wrong; hence my leaving it un-stickied for so long. Now that we have dealer confirmation, my worry has completely gone away.

[ls2gto]

Originally Posted by irpq11

Hmmmmm. Well, when I say 'I was told', I'm talking about my dealers service manager who called me. She said that it was the TAC person from GM who called her about my car. (as I said, I had someone kind enough to look into it further for me) She was told by him that it was a one way deal without the dealer reseting it.

So, then, if it's is supposed to adjust both ways, GM will surely 'fix' it and update it.

BUT, look how many people on here that have benefited from the reset AND NEVER KNEW THERE WAS A PROBLEM WITH THEIR CAR. A few of us suspected this all along. Despite many thinking we were crazy. So if GM wanted to they could just leave it the way it is and instruct the dealers to 'fix' (reset) them should owners bring their cars in with 'slow' complaints. I think most people would never even know.

I know but I have an EE degree with a computer background and just am a little skeptical of the fix as my smart ass remark in my post above indicates. For example, what if everyone's knock sensor is faulty and says it is detecting a knock when one is not actually there? Then, the computer will slowly go back toward the low octane table and here comes that damn IS 350 again.

[PQ]

Originally Posted by radz282003

I've been thinking about this too; I guess we'll all find out. I suppose, as long as GM is working on this, this simple procedure isn't too big a deal to do once-and-a-while.

IMHO - I've learned a lot from the G8 boards too, and if you contribute like this here, please don't go. I think we could all benefit from one another



I hear you. I feel better after reading this post because I'd hate to be one to contribute to a problem for the owners who performed this on their cars. Use at your own discretion doesn't make me feel disconnected from any, at least moral, responsibility if something were to have gone wrong; hence my leaving it un-stickied for so long. Now that we have dealer confirmation, my worry has completely gone away.

To both.

[Camar0wn3d]

Originally Posted by radz282003

Maybe we should rename the thread: "The 5 and 20 Mod'"

I disagree. This isn't a "MOD" it's a "HACK" - the digital equivalent of a duct tape fix.

[Tillman Speed]

To answer, yes there is both high and low octane in the beta software with LS3/L99 calibrations pulled up. This is a great thread, and helps people understand exactly how the spark calibrations work for LSx's. Keep in mind, there are also adders and subtractors based on engine coolant temp, intake air temp, graphed with rpm and g/cyl as the axis'.

9 degree (roughly) difference should for sure wake the car up. It would be nice to get a back to back dyno with fuses pulled in between runs and after letting it sit overnight on the dyno. As long as conditions are the same.

Great thread. I don't see any harm in pulling the fuses until GM comes out with a new Adaptive calibration and gives out reflashes. I woudn't call it a "MOD" either. But I wouldn't go as far as saying a "HACK" or "DIGITAL DUCKTAPE". I'm thinking it should be referred to as a "PATCH" before the dealer is involved and can properly calibrate.

Chris