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

[GQ4Life]

i need to dyno my car and make sure it is puttin down the 370wHP other peoples are..

[Danny5]

MAD props to Arrowlane Racing for figuring out the issue with my LS3!

Chris @ Arrowlane was just as curious to see if the ECU reset did anything for our LS3. He graciously ran the car on the dyno for 5 more pulls today until we knew exactly what we're dealing with.

First off. The fuse pull & battery disconnect did NOTHING for the car. We threw done 355hp on the first pull.

Confused by the car's extremely rich fuel settings, Chris did 3 more pulls comparing all the numbers. By then, the car was running hot so we put some fans on her and let her sit.

The final run we got the magic 370, but fuel is still rich. The verdict is that 1 We don't drive her hard enough and 2 the ECU is compensating for the muffler delete.

YMMV. Dyno sheet if you guys want it, but this process definitely didn't reset anything in our computer...

[GQ4Life]

Originally Posted by Danny5

MAD props to Arrowlane Racing for figuring out the issue with my LS3!

Chris @ Arrowlane was just as curious to see if the ECU reset did anything for our LS3. He graciously ran the car on the dyno for 5 more pulls today until we knew exactly what we're dealing with.

First off. The fuse pull & battery disconnect did NOTHING for the car. We threw done 355hp on the first pull.

Confused by the car's extremely rich fuel settings, Chris did 3 more pulls comparing all the numbers. By then, the car was running hot so we put some fans on her and let her sit.

The final run we got the magic 370, but fuel is still rich. The verdict is that 1 We don't drive her hard enough and 2 the ECU is compensating for the muffler delete.

YMMV. Dyno sheet if you guys want it, but this process definitely didn't reset anything in our computer...

I thought it was only my car but I have notice that eventhough I let the car warm up befor going the car doesnt seem to have its full potential the first couple times I floor it. Like oil still cold or something. Well it does have a HUGE oil pan. Never saw a car hold so much oil

[PQ]

Originally Posted by Danny5

MAD props to Arrowlane Racing for figuring out the issue with my LS3!

Chris @ Arrowlane was just as curious to see if the ECU reset did anything for our LS3. He graciously ran the car on the dyno for 5 more pulls today until we knew exactly what we're dealing with.

First off. The fuse pull & battery disconnect did NOTHING for the car. We threw done 355hp on the first pull.

Confused by the car's extremely rich fuel settings, Chris did 3 more pulls comparing all the numbers. By then, the car was running hot so we put some fans on her and let her sit.

The final run we got the magic 370, but fuel is still rich. The verdict is that 1 We don't drive her hard enough and 2 the ECU is compensating for the muffler delete.

YMMV. Dyno sheet if you guys want it, but this process definitely didn't reset anything in our computer...

So you're running on the correct fuel table for stock then. But with the muffler delete, you may have to change it. (Tune)

But like I said. There should be no reason to pull the fuses anymore as the corrections have been made. Mine is still running fine. I just haven't put any low oct. fuel in it.

[SonnyakaPig]

Originally Posted by jhmurphy

This place rocks for information!!!

Went to my dealer to get my tires sensors reset (Changed rims and tires) and told him about the fuse mod and he was amazed out how much more info is on the web and expecially in this forum than he has available to him from GM.

I know. This forum is so full of useful and interesting information, I'm blown away. I'm really loving this site.

[SonnyakaPig]

Originally Posted by Blueclyde

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.

You know a "little bit about engines?" You sound like a "G." Nice post.

Still, I'm calling the dealership tomorrow to ask what kind of fuel they use to fill up new Camaros. And if they say 87 or 89, I'm going right to my local dealer to ask them if they know anything about this fuel table mess.

[PQ]

Good luck gettng that info. GM engineers came down here with a Camaro and looked at the problem. Scott spent all day with them. When they left they basically had Scotts car running correctly. They wouldn't even let us know what the deal was. Like it's some kind of nuclear secret or something. But my car was slow, and then fast. (Vids proove it) was running with a super rich AFR and then a normal line (Dyno prooved it) so there HAS to be at least two tables or my car woulnd't have gotten stuck in that mode and not automatically corrected it's self. Because I ran about 20 tanks of 93 oct. fuel through it and still had the problem until the reset.

[GQ4Life]

Originally Posted by PQ

Good luck gettng that info. GM engineers came down here with a Camaro and looked at the problem. Scott spent all day with them. When they left they basically had Scotts car running correctly. They wouldn't even let us know what the deal was. Like it's some kind of nuclear secret or something. But my car was slow, and then fast. (Vids proove it) was running with a super rich AFR and then a normal line (Dyno prooved it) so there HAS to be at least two tables or my car woulnd't have gotten stuck in that mode and not automatically corrected it's self. Because I ran about 20 tanks of 93 oct. fuel through it and still had the problem until the reset.

doubt there is two tables but more of the car will automatically pull certain amount of timing when it senses the wrong fuel. pulling enough timing will make a car run a lil more rich.. it goes into a safe mod when it senses too much knock

[Contemporary485]

DO YOU PULL THE FUSES WHEN THE CAR IS RUNNING? OFF? kEY IN? OUT?

wHAT'S THE PROCEDURE? pARK IT, TAKE THE KEY OUT, THEN PULL? tHEM REPLACE HOURS LATER BWFORE TURNING THE CAR ON I SUPPOSE?

[GQ4Life]

Originally Posted by Contemporary485

DO YOU PULL THE FUSES WHEN THE CAR IS RUNNING? OFF? kEY IN? OUT?

wHAT'S THE PROCEDURE? pARK IT, TAKE THE KEY OUT, THEN PULL? tHEM REPLACE HOURS LATER BWFORE TURNING THE CAR ON I SUPPOSE?

NO TURN THE CAR OFF..

park the car.. pull the fuses.. leave on the side.. come back in like 4 hours and reinstall fuses.

[SonnyakaPig]

Originally Posted by PQ

Good luck gettng that info. GM engineers came down here with a Camaro and looked at the problem. Scott spent all day with them. When they left they basically had Scotts car running correctly. They wouldn't even let us know what the deal was. Like it's some kind of nuclear secret or something. But my car was slow, and then fast. (Vids proove it) was running with a super rich AFR and then a normal line (Dyno prooved it) so there HAS to be at least two tables or my car woulnd't have gotten stuck in that mode and not automatically corrected it's self. Because I ran about 20 tanks of 93 oct. fuel through it and still had the problem until the reset.

I spent hours reading through this forum, so I understand the problem about the L99 "slows." I believe it too. I never doubted you guys and especially your experiences. There were was so much documented variations in HP readings on the different dynos. Even given the different dynos and temps, something was off.

Here's my experience so far: I called the local dealer today, spoke with the service manager, told him I wanted the service department to check which fuel table my car was running on. He of course doubted me and said there was no logic behind my quierry. I of course became frustrated but because I wanted to have a good working relationship with them, I just shut up and scheduled an appointment.

I brought my car in. I called them later in the day and they confirmed that GM released a bulliten describing the exact problem that is being discussed in this thread: The 5-20.

I also called Jannetty Racing and they confirmed it.

Both Jannetty and my local Chevy dealer told me that the earlier production Camaros had the problem and after a certain production date, the problem was fixed.

My car was built right on the bubble. So my dealer is not 100% sure if the ECU was cured of the defect. So, they will fix the problem if they see that it's there. But unfortunately, their diagnostic machine is being recalibrated and updated and they're not sure it's going to be ready to use today.

So, if it's not ready (will find out shortly) they will give me my car back, in drivable condition and then schedule me to bring it back to be fixed -- that is if the car wasn't already fixed at the factory, considering it might have been built after the production date that represents the factory fix for this problem.

I'll update this thread with my findings. Thank you to C5 community for being on top of the ball and sharing this valuable information with all of us.

Personally, I have always felt that my car was performing fine, in terms of speed (it can be improved in the transmission shift points and possibly not running so rich, if it is in fact running rich). But we'll see. Perhaps it does need the fix and I just didn't know it.

[SonnyakaPig]

The verdict's in! My car does not have the SLOWS! I'm very happy. The dealer checked the computer and my car was built with the updated program.

I pretty much figured that when I read people talking about their cars spinning the wheels with traction control on from a dead stop after the 5-20 fix. Mine did that from the factory. So I guess all is good for the L99.

Oh, and the dark grey color feels like the fastest.

[GQ4Life]

Originally Posted by SonnyakaPig

The verdict's in! My car does not have the SLOWS! I'm very happy. The dealer checked the computer and my car was built with the updated program.

I pretty much figured that when I read people talking about their cars spinning the wheels with traction control on from a dead stop after the 5-20 fix. Mine did that from the factory. So I guess all is good for the L99.

Oh, and the dark grey color feels like the fastest.

Ok cool got mine 12/06/2009 so I guess Im good..
mine will spin tires and do 90 degree turn with full traction control and stability on.. which really it shouldnt
I know people with like 350z's that wont spin in the snow let alone dry with traction control on..

i always have the Grey.. I wish it was faster

[Roger Ramjet]

There are, in fact, 2 spark tables for the L99 - High Octane and Low Octane.