S10 V-8 Conversion no tachometer

[redliteracer]

I converted a 1999 v-6 s10 4wd to a v-8. I have the original ECM and one for a 1999 Tahoe. It would start and run with the v-6 ECM, but would run badly. If I swap in the Tahoe ECM, it runs good, but we have no tachometer. The v-6 ECM has a tach output. So, I took the V-8 Tahoe program and flashed the V-6 ECM and now the tach does not work. I cannot find anywhere on the HPT program where I can turn it on or off. Am I looking at it all wrong as far as flashing the ECM? Where should I go now?

[mecanicman]

http://www.hptuners.com/forum/showth...der-tachometer

[redliteracer]

I hope I don't sound like an idiot, but I cannot find anything on any screen in HPT that has anything to do with the tach. Is there something I'm overlooking or is it a software problem?

[mecanicman]

Its under engine-general on the right side(when you click engine its on first page the pops up). If your in begginer mode you may not see it, have to switch to advanced mode.

[mecanicman]

Its occured to me your running a black box pcm, your running an older 57 vortec. This setting is not available. Your tach feed comes right from your coil. You will need an inline signal adapter.

[redliteracer]

Yes, true it's a black box. I know I saw tach info on other vehicles data in HPT. The tach signal comes out of the ECM for v-6 and out of coil for v-8. I tried to swap wiring but no joy on getting tach to work that way. Right now, I have open both the v-6 cal and the v-8 cal. I was in process of copying all the v-8 info to the v-6 ECM to see if I could get it to run good and still have the tach. Do you think I am going in the right direction taht way? As far as inline signal adapter, can you give me more info?

[mecanicman]

Not sure, didnt realize the pcm output the tach signal. Maybe head over to s10forum and search around.