Tach

samsonitesamsonite · Aug 31, 2007

My 88 was wired by someone other than myself before I bought it. I know the tach does not read right, it says that at 60 MPH I am running 3500 RPM (4.0 5spd 3.73 gears and 31" tires) how do I "recaibrate" the Tach, or "Re-wire"

MAKG · Aug 31, 2007

You take that 2.3L tach and throw it in the garbage, and get one from a V6 donor with EDIS.

samsonitesamsonite · Sep 1, 2007

the truck had an origonal 2.9 that i swapped for the 4.0, I thought that they had the same tach?

MAKG · Sep 1, 2007

That could be a problem as well.

2.9Ls have one coil. 4.0Ls have three.

samsonitesamsonite · Sep 1, 2007

is a gen 1 dash so how woud i fix the tach mike?

MAKG · Sep 1, 2007

There is probably a resistor you can change (I know there is between 4cyl and 6cyl), but I don't know the values. The resistor lives in the instrument cluster.

Ozwynn · Sep 1, 2007

sam, I am all for finding the problem but i don't think the 4.0L likes the gen 1 tach. it costs $30 for a sunpro tach at autozone.

samsonitesamsonite · Sep 1, 2007

yeah yeah.. I know john, I just like the stock look... I am thinking of stripping the motor down the the basics and going with a 1st gen exploder wiring harness and dash, that will solve more problems than one. Although, with the 96 spliced into my truck I have OBDII

Ozwynn · Sep 1, 2007

there you go, there is your problem. you are trying to use an OBD1 tach with an OBDII computer...... they don't like each other. Take out your factory tach and put the sunpro in the hole. you just need to find 1 that will fit. Are you using a cable or a VSS for the speedo and how well is it working?

samsonitesamsonite · Sep 1, 2007

Im using a cable and it's working fine, i changed my speedo gear with my tire size and when im running 60 mph i get radar'ed at 59

Ozwynn · Sep 1, 2007

how you gettin that to work with the obd2?

Wicked_Sludge · Sep 1, 2007

i think what hes getting at is the fact that the obdII computer has to have a speed sensor signal to function properly...but even gen 1's had a speed sensor in the transfer case, right?

Ozwynn · Sep 1, 2007

yeah, for the computer, the speedo still ran on a cable through 91. 92's had a VSS for the speedo. I am trying to figure out how he is using the older trans with OBD2 ..... i was under the impression that there were differences.

Wicked_Sludge · Sep 1, 2007

actually the speedo was cable driven untill 95 (when they switched to OBDII)...when the switched and ran it off the VSS in the rear diff. the computer has always used the VSS in the transfer case.

samsonitesamsonite · Sep 2, 2007

well i will say this much, I have no idea how its working, its out of a 96 explorer, that much I know for a fact. the guy that did the swap and wiring was an electrical engineer.

Tach

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