Rpm tach problems. . .

[nightspeed87]

Im currently running a 1990 ecu for eprom chipping purposes.
I had to switch pin 6 and 14 I believe to make it work with my 93 harness.
The ecu works fine and have been driving with it for a few months and my only problem right now thats bothering me besides a check engine light that comes on randomly is my stock rpm gauge wont work.
Well i have done a search and found that the 90s ecu uses different rpm signals or different grounds or something meaning
the stock 93 tach wont work on a 90s ecu. The funny thing is; is that it works when i first turn the car on then after about 2 minutes it doesnt work anymore for the rest of that driving session. Why would it even start to work at all though? I even hooked up an aftermarket autometer
tach/ w shiftlight to see if I could get that to work in its place and I hooked it up correctly
and hooked up the signal wire to the white wire on the transitor harness next to the coil pack and it works 60 percent of the time and the other 40% it will start jumping around and sticking at one rpm number and not moving. Both tachs always seem to work on first start up then sometime during driving just stop working..
Why would the manually connected aftermarket tach exibit problems aswell if it was hooked up correctly? Any ideas on how to get either of these working correctly?

Also one more thing id like to add to this thread instead of starting another one would be that my car doesnt always like to start right up.
Ive considered it being the starter, but the thing is, on cold startups it cranks just fine with no hesistation.
After its at operating temperature and Ive been driving it for a while if I turn it off and then go to turn it back on it just rotates and doesnt start unless
I give it some gas. Why is that? I dont have a fuel pressure solenoid and I hear those help with warm starts.... Could this be the culprit?

 

[nightspeed87]

Actually I cut it like Jeff told me to do and the pin is still sitting in the harness.... After you cut it just leave it like that.
You can electric tape it at the cut to make sure you dont get any shortage or anything weird but thats it.
Its a white wire, just cut it like 3 inches above the connector in case you ever have to solder and splice it back together youlll have a little room to do so. My ecu is easy to access because i lifted the harness wires some for more slack, and my ecu is never connected I leave it laying on the floor directly behind the cd player housing ( on top of the carpet were the shifter cabels go, between driver and passenger footwells. ) Its easy to get to ( plug in plug out ) that way. I dont like unscrewing nothin.

Cut that white 109 wire loose ( its the 2nd wire over on the bottom row on the smallest connector )
and let me know if yours works also.

 

[wvturbo2]

Do i pull the pin first to make sure then just cut the wire or just cut the wire. My power steering exploded and i can do it tomorrow.

 

[nightspeed87]

just cut it and tape it