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post #1 of (permalink) Old 10-12-2011, 09:41 PM Thread Starter
Join Date: Oct 2011
Location: Cal
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Smile Junk yard tbi conversion

Hello all,

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
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post #2 of (permalink) Old 10-15-2011, 10:52 AM Thread Starter
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update: junk yard tbi

Update: I decided to ditch the howell approach and let the ecm control the timing. I have removed the duraspark and wired in the 8 pin ign module/hei/ with the ecs biscuit/knock sensor/ P5.

Dist - I locked down the vacum adv. with a small tack weld - for removal latter if need be. some folks remove springs and weights and etc. I just want the option to go back to the Duraspark in the future.

I will update later when we have launch off.
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