tach all over the place....

[onimitsu]

Well I did some searching and could not find anything so here it goes... well I have a 91 ford ranger with a 2.3l manual transmission. well I have changed my gauge console 2 times, my stock one had a tach and it was all over the place when I would drive and when I was at idle, the next one I got was from the junk and it came from a 91 2.3l 5-speed I put gauge over lays on it with out pulling the needles off, and that one was a little better the tach would be about 1000-500 RPM lower then what it the engine really was. The last gauge cluster I put on my truck was one from a Mazda Navajo, it was a 5-speed but I forgot what engine it had in it. Every thing works fine on this one but the tach does the same thing as the one before it but now some times the tach will say I am doing 3,000 RPM when I know I am not. And it is completely random when it does it. I have changed out the ignition control module once already. And I do have the check engine memory codes, 18, 88. Well I think that is enough info for now, but if you need to know anything else let me know. Thanks for reading all of this and any help you can give me would be HUGE! Thanks!

 

[pedal2themetal45]

I think you have a short in a wire... the tach's usualy run off the coil's... at least all the after market ones do. I'm not sure how the in dash one is actualy wired. maybe run new wires to it right off the coil and by pass all the harness crap.. if you can..
tim

 

[Bonedriver]

Change the DIS module (little grey box) monted on the front side of the intake (it'll have a connector on the top and bottom and look out for the white heat sink grease on the back - it's hard to get off your clothes). I had one of those go out and cause EXACTLY the samething on my friends 91 mustang 2.3. It ran fine... just the Tach was off. It read ~half of what it actually was. We swapped the DIS module out with mine and it fixed it so we got a new one from Advance and it was good to go.