Fuse Pull: Low Octane Fuel Fix For L99 and LS3. Reset Fuel Map for High Octane Fuel. - Page 5 - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

hot ss · 08-25-2009, 05:46 PM

paste your high tables into your low table, and never loan out your car when its almost out of gas.

is this a good time to poke fun at the 87 octane lovers that may be jumping on the "my L99 is slow" bandwagon!

Yakory1ss · 08-25-2009, 05:49 PM

Quote:

Originally Posted by Mosher

Man... I think also Dealers should be warned to NOT put regular in the V8's period! Really good find.

I totally agree. I think all dealers expecting camaro's to arrive should definitely get on the same page with this info. I'm going to make sure my dealer reads and understands this

PQ · 08-25-2009, 05:50 PM

Quote:

Originally Posted by Ject

I guess what I ment was.. from a technical point of view. I am very analytically minded so I like to know major details of stuff. (possibly why im in the IT business lol)
Pulling the fuse will actually discharge the ECM? Thus making it a blank and have to re-learn.. that sound correct? That's what I am to assume after reading everything.

No. I think it sets the computer to factory defaults that were changed with the low octane gas.

Michael_Js · 08-25-2009, 05:52 PM

I already sent a note to my dealer saying IF they fill it, use the maximum possible grade! Else, I said don't fill it...Too bad here in CA we don't get better than 91 octane :(

Info@PeddersUSA.com · 08-25-2009, 06:14 PM

Pedders has a SS and drove it about 1500 miles. We had a new style ProCharger installed on it. However, the motor is missing about 25hp before and after the install. Not really sure if the average person would even feel 25hp, but it is missing. Software, of coarse was updated. We will be doing long tubes, complete exhaust, and an electric waterpump with a custom tune. Hopefully we will be able to find the 20-25hp loss.

thanks
mike
dms

FunkyELF · 08-25-2009, 06:16 PM

Quote:

Originally Posted by jimpfromwv

My LS3 had a full tank of 87 in it from the dealer but I've been running 93 since then. I just pulled the fuses so we will see if it helps in 3 or 4 hours.
The car has been 8.72@85.03 mph in the 1/8 so if this helps it sholud be a bad mofo!

Awaiting your results.

DDustiNN · 08-25-2009, 06:31 PM

Quote:

Originally Posted by Ject

I guess what I ment was.. from a technical point of view. I am very analytically minded so I like to know major details of stuff. (possibly why im in the IT business lol)
Pulling the fuse will actually discharge the ECM? Thus making it a blank and have to re-learn.. that sound correct? That's what I am to assume after reading everything.

This is from another thread, and I posted it here but I think people are skipping over this since it's in a quote block, so I'll just paste it below:

Credit to wh0rsep0wer:

I tuned in HPTuners on my LS1 and if it is the same for an L99/LS3, this is what happens when you pull the fuses:

There are two tables values used for spark timing - high octane table and low octane table. If you use 93 octane from day one, your computer is using spark timing from the high octane table. If you got a tank of 87 from the dealer, the engine experienced premature detonation and the knock sensors went crazy, and told the computer to use the low octane timing table. What is supposed to happen is after a while of not seeing detonation from the knock sensors, the computer (ECU)tries the high octane spark timing table again. (This doesn't appear to be happening - THIS IS THE PROBLEM!!!!).

The values in the high octane and low octane tables are NON-VOLATILE MEMORY (meaning they are there even if you lose power -like when you do the fuse pull). These tables are usually adjusted when you get a custom tune, and burned into the non-volatile memory. So therefore if you get a custom tune YOU WILL NOT LOSE THESE "TUNED" VALUES with the fuse pull.

What WILL happen with the fuse pull is your volatile memory will be reset. This includes long term + short term fuel trims, knock retard, etc... but what is important in this case is the little parameter that determines which spark table to use will reset...meaning if you were running from the low octane tables before (safe + slow mode), after the fuse pull it will force the computer to try the high octane table again (super giggle fun happy rockin' mode).

However it is important to note that you shouldn't need to try the fuse pull if you've only used high octane gas since getting a custom tune, because burning the tune to the ECU resets all volatile memory. This is why it will go through the idle re-learn process and may run a little weird for the first 20 minutes or so after burning a tune or pulling the fuses.

Pulling the fuses is no different from recovering from a dead battery. The only reason I could see that it would be a problem to pull the fuses is if GM wanted to run diagnostics on the cars with the problem and needed to see the volatile values.

*mlee* · 08-25-2009, 06:34 PM

Damn this is good stuff PQ... Congrats to everyone with fast cars now.

Maybe if you had let your dealer keep the old wheels and tires he would have put 93 in the tank...

Sooooo what would happen to someone with a tune... would it wipe out everything. Could be a good fix if you didn't want to blow your warranty and needed work done.

007s 'Vert · 08-25-2009, 06:42 PM

I already knew about this trick, from what I understand this has been a long standing big secret about cars with computers. I tried this on my avalanche......unhook the battery(either post doesn't matter) turn the ignition key on and let it sit for at least an hour, turn the ignition back off, hook the battery back up and Whala! it actually works. Like any computer it has capacitors that hold a charge like that little lithium button battery you find on a mother board of a PC, whe the car battery is unhooked the computer has residual energy stored up, by turning on the ignition it helps dischsrge the computer and thus resetting the learning cycle that the computer has to go through.
Another thing to note that is very important, if you are to ever need to jump start someones car with yours, then make sure that your car is NOT on or running!, make sure the keys are out of the ignition! like any computer the one in your car can can collect information from the other car and whatever may be wrong with that car will be misconstrued as a problem with your car. If their car wont start straight from your battery then there is a whole lot more wrong with their car than just a bad battery.

PQ · 08-25-2009, 06:51 PM

Quote:

Originally Posted by mlee

Maybe if you had let your dealer keep the old wheels and tires he would have put 93 in the tank...

I spit coffee.

Ject · 08-25-2009, 06:51 PM

Quote:

Originally Posted by DDustiNN

This is from another thread, and I posted it here but I think people are skipping over this since it's in a quote block, so I'll just paste it below:

Credit to wh0rsep0wer:

I tuned in HPTuners on my LS1 and if it is the same for an L99/LS3, this is what happens when you pull the fuses:

There are two tables values used for spark timing - high octane table and low octane table. If you use 93 octane from day one, your computer is using spark timing from the high octane table. If you got a tank of 87 from the dealer, the engine experienced premature detonation and the knock sensors went crazy, and told the computer to use the low octane timing table. What is supposed to happen is after a while of not seeing detonation from the knock sensors, the computer (ECU)tries the high octane spark timing table again. (This doesn't appear to be happening - THIS IS THE PROBLEM!!!!).

The values in the high octane and low octane tables are NON-VOLATILE MEMORY (meaning they are there even if you lose power -like when you do the fuse pull). These tables are usually adjusted when you get a custom tune, and burned into the non-volatile memory. So therefore if you get a custom tune YOU WILL NOT LOSE THESE "TUNED" VALUES with the fuse pull.

What WILL happen with the fuse pull is your volatile memory will be reset. This includes long term + short term fuel trims, knock retard, etc... but what is important in this case is the little parameter that determines which spark table to use will reset...meaning if you were running from the low octane tables before (safe + slow mode), after the fuse pull it will force the computer to try the high octane table again (super giggle fun happy rockin' mode).

However it is important to note that you shouldn't need to try the fuse pull if you've only used high octane gas since getting a custom tune, because burning the tune to the ECU resets all volatile memory. This is why it will go through the idle re-learn process and may run a little weird for the first 20 minutes or so after burning a tune or pulling the fuses.

Pulling the fuses is no different from recovering from a dead battery. The only reason I could see that it would be a problem to pull the fuses is if GM wanted to run diagnostics on the cars with the problem and needed to see the volatile values.

Thank you very much, that's exactly what kind of detail I was looking for!

Verio · 08-25-2009, 06:55 PM

Well, let it sit for 1.5 hours, didn't notice any difference. Then again, wife was in the car with me... and she said it seemed faster. Either mine is operating as it should, or it needs to sit longer. Pulled em again for the rest of the night... we'll see in the mornin

stirthepot · 08-25-2009, 07:24 PM

Quote:

Originally Posted by 2011DropTop

...
Another thing to note that is very important, if you are to ever need to jump start someones car with yours, then make sure that your car is NOT on or running!, make sure the keys are out of the ignition! like any computer the one in your car can can collect information from the other car and whatever may be wrong with that car will be misconstrued as a problem with your car. ....

I dont think your car's computer is going to read data from another car via jumper cables. It cant happen, the jumpers are carrying current, not data.

Blueclyde · 08-25-2009, 07:27 PM

I have been following the discussion on this thread and am struggling quite a bit with some of the information. It is hard to argue with the results of the stop watch so it does appear that some of this is valid. I know a little bit about engines and engine controls strategy but do not have any experience with the GM controller on the L99 or LS3 engines. As I see this, both the L99 and LS3 engines should be susceptible to this problem. I have an LS3 and I know for a fact that my dim-witted dealer put 87 octane in the tank prior to deliver. They were not even aware of the fact that it called for 93 octane. I questioned them about it at delivery and advised them to read the manual.

Back to the issue of spark tables and "clearing" the ECM. Most current automotive controls systems employ what is called "Adaptive" control strategy. The primary purpose of this strategy is to allow the engine controller to learn and re-adjust as the engine/vehicle goes through its normal use/wear life cycle. This strategy is one of the ways that the auto companies insure their vehicles comply with the EPA & CARB emission useful life periods legislated for on-highway vehicles (no trivial task here). This is nothing really new. This has been around for a while. One point that I would like to make is that these systems general learn bi-directionally. Meaning, if an engine subsystem has a problem (like a plugged air filter), the system will adapt to that. Once a problem is corrected the system will adapt back. Yes, resetting adaptive parameters back to zero (or "clearing" the ECM) will generally speed that process up, but it will also occur on its own over the course of normal vehicle operation.

With respect to spark calibration tables and "93 Octane Tables" and "87 Octane Tables" I would be very surprised to find more than one spark calibration table in the control strategy. Again, I am no expert on the GM controller but I would be surprised if there are multiple tables. Generally there is one spark table that is calibrated across the speed and load range using the recommended fuel. I would think in this case with this being a performance vehicle the base spark calibration was done with high octane fuel. This engine is equipped with a knock sensor that is calibrated to detect and report occurrences of spark knock back to the engine controller. "Generally" engine control strategies use this knock sensor input data to "derate" or pull back spark advance from the base spark table. Calibrations are created to pull back the appropriate amount of spark for the input signal received from the knock sensor. There are probably other sensor based spark derate systems employed in addition to knock. Parameters such as intake air temperature and engine coolant temperature probably also have spark derates associated with them. If this is in fact the case, then none of this makes any sense, unless there are also other fueling corrections being made when the spark is being pulled out.

My point to this is do not assume what is being written hear is all correct. There is obviously something to this as again the stop watch doesn't lie. I would also submit that the folks at GM's CAC probably do not even fully understand how this all works. It would be really good to hear from a true GM expert (probably somebody from GM Powertrain calibration) to enlighten us all a little bit.

08-25-2009, 05:46 PM	#57
hot ss Drives: aqua 2ss l99 Join Date: Jun 2009 Location: Edmonton Posts: 1,215	paste your high tables into your low table, and never loan out your car when its almost out of gas. is this a good time to poke fun at the 87 octane lovers that may be jumping on the "my L99 is slow" bandwagon! __________________ May your exhaust note, sing in harmony with your blower.

08-25-2009, 05:52 PM	#60
Michael_Js SoCal C5 Family Member Drives: 2010 Camaro SS/RS - Black w/IOM; 6M Join Date: Jul 2009 Location: San Diego, CA, USA Posts: 5,299 View My Garage	I already sent a note to my dealer saying IF they fill it, use the maximum possible grade! Else, I said don't fill it...Too bad here in CA we don't get better than 91 octane :( __________________ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~ 2010 Black 2SS/RS; 6M; IOM, GFX, sunroof; ADM Race CAI; Zoomers CB; Viper Alarm; Pdaft F&R sways, Adj Endlinks, Rtrailing arms, Camber kit, strut brace, Front Trailing Arm Bushing; SLP Skip-Shift Elim; Tinted lights/windows; Hurst Short-throw; LoJack; Door & Dash ABL Mods; ********; JBA Shorty headers; AACStyle LEDs; Stillen DS rotors, Hawk Ceramic pads; Havoc Blk Chrome wheels: 20x9s; Lingenfelter Blk Al Pedals; RevXtreme Catch Can; Goodridge SS lines; Ported TB; RK Sport hood; Hotchkis chassis brace; KW V3 coilovers;

08-25-2009, 06:34 PM	#64
mlee CamaroFans.com Drives: ZLE & ZR2 Join Date: Oct 2008 Location: Conroe, TX Posts: 37,496 View My Garage	Damn this is good stuff PQ... Congrats to everyone with fast cars now. Maybe if you had let your dealer keep the old wheels and tires he would have put 93 in the tank... Sooooo what would happen to someone with a tune... would it wipe out everything. Could be a good fix if you didn't want to blow your warranty and needed work done. __________________

08-25-2009, 06:55 PM	#68
Verio Taking it 1 day at a time Drives: 2010 Chevy Camaro 2SS/RS Auto Join Date: Apr 2009 Location: San Antonio, TX Posts: 751 View My Garage	Well, let it sit for 1.5 hours, didn't notice any difference. Then again, wife was in the car with me... and she said it seemed faster. Either mine is operating as it should, or it needs to sit longer. Pulled em again for the rest of the night... we'll see in the mornin __________________ Order#: NJWGTF 1100, Preliminary order accepted 04/27/2009 6000, Delivered to the customer 07/23/2009 - 3 Months (worth the wait!!)

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08-25-2009, 06:14 PM	#61
Info@PeddersUSA.com Drives: 5th Gen Rental Join Date: Aug 2007 Location: New England Posts: 1,901	Pedders has a SS and drove it about 1500 miles. We had a new style ProCharger installed on it. However, the motor is missing about 25hp before and after the install. Not really sure if the average person would even feel 25hp, but it is missing. Software, of coarse was updated. We will be doing long tubes, complete exhaust, and an electric waterpump with a custom tune. Hopefully we will be able to find the 20-25hp loss. thanks mike dms

08-25-2009, 06:42 PM	#65
007s 'Vert Formerly Lil'BlueCoupe Drives: '13 2LT/RS Vert, Summit White Join Date: Jul 2009 Location: Vegas Baby!!!!!!!! Posts: 1,786	I already knew about this trick, from what I understand this has been a long standing big secret about cars with computers. I tried this on my avalanche......unhook the battery(either post doesn't matter) turn the ignition key on and let it sit for at least an hour, turn the ignition back off, hook the battery back up and Whala! it actually works. Like any computer it has capacitors that hold a charge like that little lithium button battery you find on a mother board of a PC, whe the car battery is unhooked the computer has residual energy stored up, by turning on the ignition it helps dischsrge the computer and thus resetting the learning cycle that the computer has to go through. Another thing to note that is very important, if you are to ever need to jump start someones car with yours, then make sure that your car is NOT on or running!, make sure the keys are out of the ignition! like any computer the one in your car can can collect information from the other car and whatever may be wrong with that car will be misconstrued as a problem with your car. If their car wont start straight from your battery then there is a whole lot more wrong with their car than just a bad battery.

08-25-2009, 07:27 PM	#70
Blueclyde Drives: 2023 ZLE Join Date: Jun 2009 Location: Detroit Posts: 1,717	I have been following the discussion on this thread and am struggling quite a bit with some of the information. It is hard to argue with the results of the stop watch so it does appear that some of this is valid. I know a little bit about engines and engine controls strategy but do not have any experience with the GM controller on the L99 or LS3 engines. As I see this, both the L99 and LS3 engines should be susceptible to this problem. I have an LS3 and I know for a fact that my dim-witted dealer put 87 octane in the tank prior to deliver. They were not even aware of the fact that it called for 93 octane. I questioned them about it at delivery and advised them to read the manual. Back to the issue of spark tables and "clearing" the ECM. Most current automotive controls systems employ what is called "Adaptive" control strategy. The primary purpose of this strategy is to allow the engine controller to learn and re-adjust as the engine/vehicle goes through its normal use/wear life cycle. This strategy is one of the ways that the auto companies insure their vehicles comply with the EPA & CARB emission useful life periods legislated for on-highway vehicles (no trivial task here). This is nothing really new. This has been around for a while. One point that I would like to make is that these systems general learn bi-directionally. Meaning, if an engine subsystem has a problem (like a plugged air filter), the system will adapt to that. Once a problem is corrected the system will adapt back. Yes, resetting adaptive parameters back to zero (or "clearing" the ECM) will generally speed that process up, but it will also occur on its own over the course of normal vehicle operation. With respect to spark calibration tables and "93 Octane Tables" and "87 Octane Tables" I would be very surprised to find more than one spark calibration table in the control strategy. Again, I am no expert on the GM controller but I would be surprised if there are multiple tables. Generally there is one spark table that is calibrated across the speed and load range using the recommended fuel. I would think in this case with this being a performance vehicle the base spark calibration was done with high octane fuel. This engine is equipped with a knock sensor that is calibrated to detect and report occurrences of spark knock back to the engine controller. "Generally" engine control strategies use this knock sensor input data to "derate" or pull back spark advance from the base spark table. Calibrations are created to pull back the appropriate amount of spark for the input signal received from the knock sensor. There are probably other sensor based spark derate systems employed in addition to knock. Parameters such as intake air temperature and engine coolant temperature probably also have spark derates associated with them. If this is in fact the case, then none of this makes any sense, unless there are also other fueling corrections being made when the spark is being pulled out. My point to this is do not assume what is being written hear is all correct. There is obviously something to this as again the stop watch doesn't lie. I would also submit that the folks at GM's CAC probably do not even fully understand how this all works. It would be really good to hear from a true GM expert (probably somebody from GM Powertrain calibration) to enlighten us all a little bit.