Stock Tachometer Problem

[JessesTalon]

Ok so everytime I go WOT or get to high rpm's (3500) and above and give it a little gas the stock tach goes all the way down to zero or like 500 rpms, but as soon as I let off the gas the tach goes right back to where it should have been.


could the problem be a 91 ecu in a 90 that the wires got switched or something?

also my dash lights don't work could this be the same cause, I checked fuses and everything but everything seems good... It's a royal pain in the ass wiring job, and the a/f gauge and the egt don't work either, I don't know what to do.

 

[JessesTalon]

Well got it figured out... turns out the ECU was the problem. I plugged in the TMO ECU and took me a while but got the code in and the car ran great...

Dash lights are still out though, really sucks driving at night!

 

[luv2rallye]

Check for faulty rheostat.

 

[JessesTalon]

Well a friend came over who has lots of eletrical expierence and we took apart the dash and took out the gauge cluster and checked with my snap-on multimeter all the lines going to the dash, it seems somewhere between the cluster and the ground is faulty, the problem is the only way to find where the ground is completly taking apart the entire front dash and tracing the ground wires inch by inch.

We said eff it and moved on to getting the egt and a/f and bosot gauge lighting to work and the ecu wire's were in poor condition and we saudered up a ton of wires that were loose and barely stuck in the plug. grrrrr little gremlins everywhere!