LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Speedo Way Off

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Old Jan 13, 2012 | 01:16 PM
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Default Speedo Way Off

Still working out the kinks with the "new to me" Z28. Today I took it out on I95 and realized that when in 6th gear, RPM around 1400 or so, and probably doing around 65-70mph, the speedo was sittin pretty at about 35mph.

As you can see, its way lower than actual speed.


Where do I start with problem solving? Tune?...Speed sensor somewhere?
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Old Jan 13, 2012 | 01:37 PM
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UHHHH Also noticed that I do not appear to have a working REVERSE LOCK OUT. I was upshifting from 4th to 5th and went to far over and barely started to grind reverse!


I also noticed when the car was in the shop that on the topside of the transmission there was a sensor of somesort that was plugged in, but had no wires going to it.


blah smh
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Old Jan 13, 2012 | 02:03 PM
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Wow, you got all kinds of trans issues; no 2nd gear, no reverse lockout, sensors not plugged in, now the speedo is WAY off? No offense, but did you drive the car at all before you bought it? Sounds like you got a deal "to good to be true" somebody else's basketcase...I would have had a mechanic look it over good before you bought it and test driven the **** out of it. If you found all this stuff out BEFORE you pulled the trigger and bought it you probably could have negotiated a lower price. Maybe try plugging in the sensor in the trans and see what happens?
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Old Jan 13, 2012 | 02:24 PM
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Lol, i basically got the car for free. 107k miles, uncracked leather, decent shape,and all the mods in my sig.. I paid $1,150 for it. But it was not running when I bought it. It needed an opti, plugs,wires. I Now it runs great. Now that im driving it, im discovering the transmission issues. The t56 was swapped in. The car was a A4. Im really wondering what that sensor is on top. Its plugged in, but there are no wires going to it. hmm..
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Old Jan 13, 2012 | 02:25 PM
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The PCM needs to be reflashed if it came from an auto car. You can have it done at pcmforless.
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Old Jan 13, 2012 | 02:39 PM
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Does pcmforless just sell programmed pcm's? I dont want the car to be down for a week+
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Old Jan 13, 2012 | 03:35 PM
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You could buy the cables and software and do it yourself for about the same price. I don't see how the speedo calibration could be that far off. Gears and tires would only throw it off 5-10mph in the 60mph range, maybe 15mph, but 35mph (or 50%) tells me something else is going on. I don't know how the M6 speedo sensor is set up, but it could be the wrong speedo gear or reluctor ring or whatever they use.

You might try posting in the transmission section of LS1tech and ask the M6 gurus what they think.
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Old Jan 13, 2012 | 04:16 PM
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I was just reading about the a4-t56 swap and found out that if the pcm is not tuned for the m6 it will be about 50% off. Also the tutorial says the skip shift and reverse lockout solanoid are optional..... guess the po opted out of those
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Old Jan 13, 2012 | 06:27 PM
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Oh, I didn't know it was a swapped M6. That'll probably do it. Hit up Solomon at lt1pcmtuning.com and I think he has a loaner deal on cables and software and he will tune it at a reasonable price. No down time required.
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