Calibrated My Speedometer, What a Difference

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Mar 8, 2003 | 08:48 AM

turbonatr

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From: Gun Friendly, Pennsylvania, USA!!

Calibrated My Speedometer, What a Difference

I run 32x11.50s on my 302 '95 XLT and got around to calibrating my speedo yesterday. I used the 8.86 constant according to the tech article for a 32x11.50 tire. Wow! I didn't expect much, but what a difference. The trans used to stay in a higher gear instead of downshifting which really killed speed on hills. It eventually downshifted, but usually too late. It's perfect now. Feels like I picked up power since it shifts when it's supposed to. Before calibration, it was running 2000rpm at 70mph. Now I tach 2000rpm at 75mph. I'm guessing the speedo was off about 5mph. Can't wait to see what kind of mileage I get.

I still think I am going to go with 4.10s, though.

Mar 11, 2003 | 12:10 PM

Tahoe1990EB

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Calibrated My Speedometer, What a Difference

I'm wondering if a non-calibrated speedo effects the E4OD when the odometer is not digital. I have a 1990, 5.8L, with 31's and am wondering if the slightly larger than stock wheels are throwing off shifting points. I don't really mind the speedo being off, but if the shift points are being effected it seems worth it to make the correction.

Mar 11, 2003 | 12:16 PM

pyro515

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Calibrated My Speedometer, What a Difference

Forgive my ignorance, but how do you correct it? Is it a speedo gear or something else?

Thanks,

Mike

Mar 11, 2003 | 12:36 PM

Tahoe1990EB

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Calibrated My Speedometer, What a Difference

Pyro: I've just been searching the old posts and the deal seems to be if you have a digital odometer you can calibrate through a sequence of steps which codes are entered using the LCD odometer display. If you have a non-digital then you have to change the gear which drives the speedo. Do a search on "calibrate" or "speedometer".

But I'm still interested to know if the computer in the E4OD gathers any info from the speedo?

Mar 11, 2003 | 12:42 PM

pyro515

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Calibrated My Speedometer, What a Difference

Tahoe,

Cool, I have the digital odometer so I will do a search.

Thanks,

Mike

Mar 11, 2003 | 06:53 PM

turbonatr

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From: Gun Friendly, Pennsylvania, USA!!

Calibrated My Speedometer, What a Difference

The calibration sequence can be found in the Tech Articles section.

Mar 11, 2003 | 11:24 PM

steve83

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Calibrated My Speedometer, What a Difference

Tahoe
There's no computer in the E4OD - it's controlled by the EEC, which DOES receive a signal from the PSOM. The same signal used by the cruise servo.

You can read the procedure and other interesting stuff here.