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4.56 gear problems solved...woohoo

1102 Views 7 Replies 4 Participants Last post by psychoslaphead, Jun 26, 2005

Discussion Starter · Jun 26, 2005

The dealer had to reflash or replace my prom and I started over. Not sure if my truck had a bad ECM prom before I started, but to recap:

When you first have the gears installed, the traction control will be whacked because the sensors are getting bad information. What happens is the vehicle dies when it hits second gear, no matter what speed you are moving at. This can be hazardous to your health the first time it happens as you pull out into traffic from the gear shop. You will have to disable the T/C manually until you get into the ECM to tell it you have a new gear ratio. Dealers CANNOT do this with standard GM software - you must use an aftermarket tuner.

Here is where it gets painful - I tried Crane and Superchips tuners, neither would even load on my truck. I then tried a Granatelli, which would load, but things got even crazier. Now my speedo error got WORSE, and the T/C light came on permanently, GRRRRR. This all takes time, I'm driving a crippled truck for almost a month trying to sort this all out. Back to the dealer let them work over the ECM (they fixed a bunch of other issues too), and this time I grab a different Granatelli off the shelf, and it works PERFECTLY. I'm rockin now. I've raised my shift points and rev limits, installed a very aggressive tune (requires 91 octane), firmed up the shifts, and I'm driving a REAL HOT ROD, not a poseur. And with the Magnaflow exhaust, it SOUNDS like one too.

Thanks Jim for all your hard work on this stuff, everything you've posted has been true in my experience, and at this point I can't recommend the gear change enough to others... :seeya

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beer100

· #2 · Jun 26, 2005

The moral of the story....

So the moral of the story is to have a programmer, one proven to work on your vehicle, on hand before having the gears changed.

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Zack

· #3 · Jun 26, 2005

4:56 and 05-6 speed??

Do you think this programing issue will affect my SSR since it has no shift points and no traction control???

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beer100

· #4 · Jun 26, 2005

I does have an advanced engine control system. One that relies on knowing the correct speed of the vehicle.

I always wondered why it doesn't get this by reading the speed from the abs system. :confused Who knows, maybe it does.

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JimGnitecki

· #5 · Jun 26, 2005

beer100: All 3 software manuals I have been reading say that the VCM calculates its vehicle speed from the number of pulses per minute from the VSS (vehicle speed sensor), which is located on the driveshaft side of the rear axle on SSRs and on the output shaft side of the Corvettes (they have a transaxle).

Most of the microtuners and tunign software packages AUTOMATICALLY corrct the speedometer AND shift points once you change just ONE field in the software: the gear ratio. If you screw around with any of the other fields related to that screen, you will likely screw things up.

The reasons are too lengthy to list here, but trust me: don't screw with the other settings on that software screen!! Just change the gear ratio from 3.73 to 4.56 and save.

Jim G

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SA13355

· #6 · Jun 26, 2005

Jim

Jim, per your comment about too lengthy to list here,
maybe we should have a "tuner" forum here to go with general and tech?

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Discussion Starter · #7 · Jun 26, 2005

beer100 said:
I does have an advanced engine control system. One that relies on knowing the correct speed of the vehicle.

I always wondered why it doesn't get this by reading the speed from the abs system. :confused Who knows, maybe it does.

Before I corrected the ratio with the tuner, I got a message on the computer to "Service Brake System", along with the traction control not working properly. The two may share a sensor.

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Discussion Starter · #8 · Jun 26, 2005

Zack said:
Do you think this programing issue will affect my SSR since it has no shift points and no traction control???

The Granatelli will ask you whether you have an auto or manual transmission and presumably give you different options for each. For the manual, I'm guessing you could adjust the rev limiter only instead of shift points.

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