details and proof please [octane levels]

[Supersport2011L99]

Why does ONLY pulling the fuse work? If I'm not mistaken when you pull a fuse that cuts the flow from the main power to the octane table, right? and in result "resets"? So why doesn't it reset if the main power is taken out? I'd like to hear from people that have an understanding of electricity if possible.

...also where can I find a original GM document that states the octane table isn't active and that it has to be manually reset by pulling fuses?

Thanks in advance

[Cam2011]

I believe you'd achieve the same goal by pulling the main power, but then you would have to reset all your other settings, this way you isolate the fuses you need to reset the octane table.

[Supersport2011L99]

Originally Posted by Cam2011

I believe you'd achieve the same goal by pulling the main power, but then you would have to reset all your other settings, this way you isolate the fuses you need to reset the octane table.

No argument there but the word on the forum is that only a fuse pull works and taking the battery out unfortunately doesn't work.

[Russell James]

Ask your dealer to look up bulletin PIP4728.

That came out back when the '10s were doing it. That bulletin is for the '10 L99, but many have found it to work on all 5th gens.

The fuse vs battery disconnect thing may just be in how the memory is saved or reset. Different types of power downs may do different things. The bulletin specificly says to pull the fuses. Plus that saves you from having to reset the window indexing.

[E.T.]

I don't know the "magic" behind all this either, but here is what GM says:

Originally Posted by garcmol

Well, call it BS, call it magic, I don't really have the answer. All I know is #5 is the main ecm fuse and #20 is the ECM/ignition. I know that cutting power to the entire fuse panel does nothing. Maybe you just pull these so #17 is still powered (which is your sensing diagnostic module/ignition). Maybe leaving power to the rest of the fuses causes your knock sensors to readjust and think 93 octane. Then you put your #5 and #20 back in and the magic happens.

Point is, I reposted how to do it. Do it, don't do it

Document ID: 2366489
--------------------------------------------------------------------------------

#PIP4728: Higher Than Expected 0-60 MPH (97 KPH) Acceleration Time - (Nov 4, 2009)


Subject: Higher Than Expected 0-60 MPH (97 KPH) Acceleration Time


Models: 2010 Chevrolet Camaro

with V8 Active Fuel Management Engine (RPO L99)

and 6 Speed Automatic Transmission (RPO MYC)




--------------------------------------------------------------------------------

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Some customers may complain of higher than expected 0-60 MPH (97 KPH) acceleration times when hot ambient temperatures are present. In some cases, they may report 0-60 times around 7 seconds.

This may be the result of the vehicle being filled with regular grade unleaded gasoline at one time. If the vehicle has been filled with regular unleaded gasoline, the ECM may be compensating for the lower octane by retarding the ignition timing during certain driving conditions.

Recommendation/Instructions:
If SI diagnosis does not isolate the cause of this concern, perform the suggestions below if the customer wants the best performance from their Camaro:

•In an area where it is legal to do so, take a snapshot of a 0-60 WOT acceleration event and compare the vehicle speed parameter to the snapshot timer to determine the 0-60 MPH time.
•Determine what gasoline octane the customer has been filling the vehicle with.
• 2a. If they have never used anything but premium unleaded with a posted octane of 93 or higher, go to step 3.

• 2b. If they occasionally use regular or mid-grade gasoline, the gasoline must be removed from the tank and it must be refilled with premium fuel of 93 octane or greater. This can be done by advising the customer to switch to premium fuel of 93 octane or greater and returning after a few tanks of premium fuel have been consumed. Or, if immediate results are necessary, drain the fuel tank, refill it with premium fuel of 93 octane or greater, and drive the vehicle at least 15 miles to purge the old fuel out of the fuel rail and lines.

•Reprogram the ECM with the latest TIS2Web calibrations to reset the ECM adapts. Normally this reset can also be accomplished by pulling the 2 main ECM fuses (F13R, #5 and F20U, #20) shown in the ECM Power, Ground, MIL, and Serial Data Schematic (SI Document # 2209065).•In an area where it is legal to do so, take another snapshot of a 0-60 WOT acceleration event and compare it to the original snapshot to determine if the 0-60 MPH time has increased. If an increase is noted, advise the customer that they should only use premium unleaded gasoline with a posted octane rating of 93 or higher to continue getting the best performance from their Camaro. This is outlined on page 8-45 of the owner's manual. GM Connect Message G_0000037144 was also sent out on 9/2/2009 about filling stock units with premium gasoline.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION


© 2009 General Motors Corporation. All rights reserved.

[slick rick]

WOW this is really bugging you huh?

[Caspers2SSRS]

Thanks E.T ....that should pretty much wrap things up.

[Rockin the BlueSS]

Originally Posted by Supersport2011L99

Why does ONLY pulling the fuse work? If I'm not mistaken when you pull a fuse that cuts the flow from the main power to the octane table, right? and in result "resets"? So why doesn't it reset if the main power is taken out? I'd like to hear from people that have an understanding of electricity if possible.

...also where can I find a original GM document that states the octane table isn't active and that it has to be manually reset by pulling fuses?

Thanks in advance

well the computer has an energy storage device somewhere (a battery of sorts) and that is why when you pull the fuses you have to leave it over night. It may be that when all power is removed from the vehicle that extra backup is used the protect the ecu and it saves all the setting that it has learned. The fuse pull works around this by just removing the power the memory part of the ecu so that when the power is returned it must learn everything all over again.


But if you don't trust it that much it cool just don't pull the fuses, i would venture to say more than 90% of camaro owners wont ever pull the fuses. it is just for those that have the speed addiction

[cab2g]

Just wondering, if the bulletin is only for 2010 L99 Camaros, can you reasonably assume that the issue never existed for the LS3 and that the issue is resolved for 2011+ models? Why would GM create a TSB for only L99 if it could possibly affect the LS3?

Also if GM is aware of the issue, what would have stopped them from resolving the issue in the next model year or a mid-model-year software update?

[Rockin the BlueSS]

Originally Posted by cab2g

Just wondering, if the bulletin is only for 2010 L99 Camaros, can you reasonably assume that the issue never existed for the LS3 and that the issue is resolved for 2011+ models? Why would GM create a TSB for only L99 if it could possibly affect the LS3?

Also if GM is aware of the issue, what would have stopped them from resolving the issue in the next model year or a mid-model-year software update?

they do not see this as a problem they see the car as functioning as designed...

[FL1CK]

Pulling the fuses lets capacitors drain, removing battery power still has power to the capacitors and therefore nothing is reset. As for the tables, that's in a binary setting that GM engineers know. I don't have spare parts sitting around to test as to why it works, but this is just a basic electronics knowledge from my experience as to why fuses are pulled and not disconnecting the battery.

~U.S. Navy Electronics technician for 11+ years and counting...

[The Stig]

Originally Posted by Supersport2011L99

Why does ONLY pulling the fuse work? If I'm not mistaken when you pull a fuse that cuts the flow from the main power to the octane table, right? and in result "resets"? So why doesn't it reset if the main power is taken out? I'd like to hear from people that have an understanding of electricity if possible.

...also where can I find a original GM document that states the octane table isn't active and that it has to be manually reset by pulling fuses?

Thanks in advance

Fuses #5 and #20 don't power the octane table. They power the ECM - so you're resetting the whole ECM