Thanks for allowing me to post on this informative site!
I have read so much on this site my head hurts. I was entertained by the older post and bashing but i do need some guidance.
I am trying to save money and I attempting to do a TBI conversion on my 89 yj. Junkyard style. Ie wire-harness 90 astrovan 4.3 - o2,map,tps,aic, etc. gm tbi 94 s10./ homemade conversion plate. 7747 computer.
I am almost there except for the top secret tach filter that goes to pin b5 on the 7747 computer. I wanted to use the Duraspark combo with the accel coil, but I need a tach filter of some sort to talk GM language from my duraspark module?
I spoke with Howell and I can purchase CAL-prom and the wire-harness( with a built in tach filter) from them.$$ I would like to do it myself if possible or feasible.
If I go the Howell route - I may need the msd type tach filter and CAL-PROM
I have read the GM duraspark conversion under - short wheel base- wiring clinic but unsure of the tach signal.
I believe if I can get a clean square wave tach signal - the ECM will fire my injectors and batta bing! no mo red jeep parked in garage = happy wife
Any thoughts? Dennis