now just complety out of curiousity why the hell does the sohc cam TACH not work on the DOHC motor like a tach gets a signal from the ignition coil right and there both 4cly it does not make any sence to me and if it has something to do with the wiring could’t a simple hard wiring for the intearior harness(the harness next to the passenger door) be hard wired to the coil
once again completly out of curiousity
there is different redlines for the sohc and dohc. The ecu is also different for both engines. Because the ECU is different the dohc ecu will not work with the sohc tach. It gets a different signal.
As for a way to hard wire. Why even try it? or think about it. I bought a dohc tack for $10.
The reason they won’t work is becasue the DOHC tach is electronic and the SOHC tach is cable driven.
yes a digital signal vs an analog signal
that’s not the case.
i can’t even think of a car on earth that has a cable driven tach.
dont older american cars have em?
i’m almost positive it’s still a wire off the ignition coil with them, at least it is with my '69 Opel GT (not american, i know).
maybe you’re thinking of cable driven speedos? they were used on a lot of older cars. i believe pretty much every car from the muscle car days and earlier used these. some cars still used them in the early 90’s (not 240s though).
lol are u serious cable drivin tach how is that even possible the tach should have nothing to do with the computer FOR EXSAMPLE if anyone here ever bought a tach at canadian tire or whatever the instrustions simple say one wire to ignition coil and one to power one to ground etc. i think the dohc has a different coil thats the only reasone i can think of. becasue if u think about it to get a tach signal all u have to do is change the gauge cluster make sense of that!
i believe that the difference is that the SOHC tach reads the signal off the leading edge and the DOHC tach reads off the trailing edge of the signal (or vice versa).
though if that was the case, you’d think that the SOHC tach on a DOHC would still read something, though it might be incorrect.
that’s my take on it anyway, maybe someone who knows for sure will chime in here?
nobody knows
LOL man you guys make me laugh. question?..do you see a cable anywhere on the transmission at all? really ? the only cables on the car are thottle, ebrake, and cruise, hood and trunk release. its electronic. distributor sends the signal out. for rpm or the cas on sr’s. are you gonna hook up a aftermark tach to your cable? also think of the question you asked. well not so much you but the replies. sohc vs dohc could the difference be an extra cam and the rpm of the cams are now different?
wow
The reason they won’t work is becasue the DOHC tach is electronic and the SOHC tach is cable driven.
-Dustin
'93 Green Hatchback with a Black door.
12.7@111
you guys do you know that you don’t have to swap out the vss when you do a soch to doch swap right.
only things i can think of is the pin-out of the tach signal is different due to the use of a different coil or the actual transmission of the signal reads differently on the sohc tach and dohc tach.
but why such a deep thought, dohc tach’s are cheap and easily obtainable. 
just curious
They are both electronic, however the tach signal is different.
I always thought he had to do with how triggering occured. eg positive triggering as opposed to negative.
Andrew.