Here's a thought... (Cruise Control & Incorrect Speed)

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07-21-2004, 09:21 AM

Merlin 91/97

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Here'* a thought... (Cruise Control & Incorrect Speed)

I posted two different topics about different issues a while back....

Cruise Control Issues
http://www.bonnevilleclub.com/forum/...ic.php?t=20910

&

Incorrect Speed
http://www.bonnevilleclub.com/forum/...ic.php?t=21454

I was wondering if the two could be related?
If so, might knowning that help narrow down the problem.

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07-21-2004, 12:08 PM

repinS

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hmm, I have no idea whether my cruise even works or not

But after looking over your most recent topic again, what padgett has to say sounds interesting:

Quote:

I do know there is a PROM calibration byte for MPH. Would sound like you have a speedo for a 3.33 axle and a 2.94 actual gear but the VSS (vehicle speed sensor) is supposed to be fixed at 4000 pulses per mile reguardless of ratio (sensor driven by output shaft ?).

I may be experiencing incorrect speed readings as well, and I'm not on the original tranny job (previous owner did it).

I cruise just around 2000rpm when it reads 100km/h. All the more reason to check my RPO codes and figure out what my car really came with stock.

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07-21-2004, 02:47 PM

padgett

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Will need to check our 90 Bonneville with a scan tool. The Reatta has a digital readout and the same drivetrain, 2.94:1 axle for a hair over 35 mph/1000 rpm in o/d lock-up. (71.4 mph at 2000). Actual is about 2% more because of the 225x60x16s (same size on both cars).

I believe these long highway gears are the reason the torque peaks at 2000 rpm.

That said, I believe the speedo is driven by an analog signal from the ECM and like any analog guage, its calibration could be off (in the gauge). Another reason to check for the actual mph reading with a scan tool.