For my birthday I invested in a scanning cable and some good software from tts power systems. I have always known my speedo, tach and temp gauge were off, but never by this much. The RPMs are off by about 450(what a differance an extra 450 into the redline makes too ), the miles per hour is about 7 miles to high, and the temperature gauge is reading 130 when my coolant sensor is telling the ECM 180.5. The good news is my battery volts were nearly on the mark. So how did this happen(like this since I bought it) and how can I recalibrate it? I could not find info anywhere on this including the GM shop manual so you are my new hero if you know the answer to this question.


[This message has been edited by UVA3rdGen (edited April 17, 2001).]

 

Well you have a little bit of a problem....

Which one is right, the gauges, or the ECM????

Start with the speedo. Drive down a road at exactly 60 on the dash unit; time how long it takes you to drive a measured distance, like 10 miles on the interstate according to the little green numbers, and get a correction factor for the dash unit.

Same with the RPM: hook up some kind of an engine analyzer, or even a frequency counter, and measure the actual RPMs; compare that against the dash one and the ECM one.

Etc...

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"So many Mustangs, so little time..."
ICON Motorsports

 

All the family cars seem to be on the side of the ECM. As far as RPMs go, the dash says I am idling at 1100, but my TPS is properly adjusted and if I go much lower on the IAC it is a real rough idle. The comp says I am idling at 750, and judging from the setting the timing with the spark advance disconnected, the computer seems to be right about that also. I really need to learn to burn my own prom, but that will come later. What would cause my ECM to report the wrong RPMS? I can diffinitely see getting MPH wrong with all the variables, but I think the computer is right about both.

Thanks for the advice though.

[This message has been edited by UVA3rdGen (edited April 17, 2001).]

 

? anyone ?. How do you recalibrate your dash gauges?

 

Pull the needles off and adjust them.

 

Ron you knucklehead, for inaccuracy like he's talking aboput just pulling the needles won't help. I believe that there are shops that specialize in calibrating guages, where they will open it up and actually adjust the resistances/coils that move the guage to mek them accurate. Of course this prolly costs more thna custom dash with autometer guages in it though.