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Old 10-06-2012, 07:44 AM   #85
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Originally Posted by PQ View Post
Very interesting. Thanks for going the distance and checking this out PQ.

All I can figure is that they either cleared the memory with test equipment during their testing, or as NFERNOSS said, a different fuse. Or, something altogether different fixed the issue.

The PIP does mention fuse #20. I suspect that this circuit may hold some parasitic voltage for a short period of time, so that's why GM calls to remove this fuse for the ECM reset. That's why I specifically stated to wait 45 minutes before testing, so any parasitic voltage could bleed off before testing. Good stuff.

I would have thought that GM would have revised the ECM logic to start at maximum timing advance with every new start of the engine, then back off and hold back advance as dictated by the knock sensors until the engine is restarted again. This is the logic that most cars use.

GM engineers, please speak up.
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Old 10-06-2012, 10:10 AM   #86
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They did tell me the problem, car was in the low octane table thanks to dealer original putting 87 in it the PDI or what ever the test of the car is called when it gets to the dealer ship. They reset it to the high octane table. They spent an entire day working on it and finally figured out that was the problem with many calls with Al Op and his team during the day.
Oh. I forgot about that. I was mainly referring to them not telling you how to fix it. I remember that day. I was on pins and needles over here.

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Funny how the TSB from GM says pull fuse 20 under the hood and fuse 13 in the trunk.

I have pulled my fuses a couple of times since the fuse pull was discovered. On time after the only gas I could get was 89 on a trip. The fuse pull worked everytime. Fuses pulled 5 and 20.
With no juice in those fuses, how could it make a difference?

Now I still KNOW that the car can get stuck in a low octane, retarded state. And Apparently the fuse in the trunk is the one to pull for the ECM but how can fuse 20 make a difference when it's power is killed when you turn the ignition off?
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Old 10-06-2012, 10:21 AM   #87
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Oh. I forgot about that. I was mainly referring to them not telling you how to fix it. I remember that day. I was on pins and needles over here.

With no juice in those fuses, how could it make a difference?

Now I still KNOW that the car can get stuck in the low octane table. And Apparently the fuse in the trunk is the one to pull for the ECM but how can fuse 20 make a difference when it's power is killed when you turn the ignition off?
Electrical gremlins?
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Old 10-06-2012, 10:24 AM   #88
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Originally Posted by strych9 View Post
Very interesting. Thanks for going the distance and checking this out PQ.

All I can figure is that they either cleared the memory with test equipment during their testing, or as NFERNOSS said, a different fuse. Or, something altogether different fixed the issue.

The PIP does mention fuse #20. I suspect that this circuit may hold some parasitic voltage for a short period of time, so that's why GM calls to remove this fuse for the ECM reset. That's why I specifically stated to wait 45 minutes before testing, so any parasitic voltage could bleed off before testing. Good stuff.

I would have thought that GM would have revised the ECM logic to start at maximum timing advance with every new start of the engine, then back off and hold back advance as dictated by the knock sensors until the engine is restarted again. This is the logic that most cars use.

GM engineers, please speak up.
Agreed.

One thing I know is that the car WILL get stuck in a low octane retarded timing state. My complaint all along was that it didn't revise automatically and I suspect that it's a way for them to keep the car at it's uber safest level to not have as many warranty claims. I know there are people out there who are stuck in the low octane table and don't know it.

I'm a little confused at all of the people who SWEAR that it helped. Mine was at the dealer just before the fuse pull. (It was always at the dealer for this. The dealer appologized to me for telling me that I was wrong when that bulletin came out about the issue) I didn't do any timed testing between the last time the car was at the dealer and the day I did the first ever 'Fuse Pull'. The dealer told me they reset the computer but I was already in 'Done' mode with the car waiting for the engineers to put out a TSB.

To tell you the truth I was hoping I'd find some juice in at least one of those fuses. It was my fuse pull that blew this whole thing open and I will own up to that. My findings on my cars immediate and undeniable performance jump had to have been from my last trip to the dealer. And we were right about the low octane settings not adjusting back to a more advanced timing (can't deny that, it was the engineers that said that) but the fuse pull for the moment seems to be egg in my face.

I tried to get EVERYONE to time their cars before and after but NOBODY did. If you go through the fuse pull sticky you'll see me saying it over and over and over. I finally just gave up.

And now We'll all be laughed at pretty hard. I will take that square on the chin and accept that. But I think anyone that had the same chain of events in my shoes would have done the same.

I feel a little responsible for this. So I'm going to make an effort to find out exactly what fuses and where they are so that we can let people know properly. After all, there are people out there with SSs that are nannied and don't know it.
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Old 10-06-2012, 10:28 AM   #89
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PQ - maybe try filling her up with 87 to drop her down to the low octane table and time some 0-60 runs. Then fill her back up with 93 and pull the fuse in the trunk to see if that does anything?
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Old 10-06-2012, 10:28 AM   #90
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Also, I have come to understand that it may not be a table. There may be no 'Low table' or 'High table' but an averaged timing advance or retard. Like resetting a trip meter and MPG meter. The farther you drive the more miles it will take to get changes to record but resetting it makes it record changes immediately.
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Old 10-06-2012, 10:29 AM   #91
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PQ - maybe try filling her up with 87 to drop her down to the low octane table and time some 0-60 runs. Then fill her back up with 93 and pull the fuse in the trunk to see if that does anything?
I'd be willing to do that if someone has a stock L99 for me.

I'm .............. well ............. TUNED would be an understatement.


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