Hi,

I'm looking at swapping a 1227165 into my 84. Most of the lines are the same, but the grounds seem to be different. I don't have all the wiring diagrams for an 89 S10 that the ECU came from, but I did find some on line. Two of the grounds on the ECU are tied together and labeled as direct grounds.



Can anyone tell me what "Direct Ground" means in this context?

Thanks,
Bob

It has to do with the injector driver setup relating to the ground side of the driver.

The injector driver in the 7165 was designed to either control 1 peak/hold injector (tbi) or several saturated injectors(port). When the pins D9 and D10 are connected, the driver is set to peak and hold mode and will control the TBI injector. If D10 is grounded, the driver is set to saturated mode and will control regular port injectors. Going by the diagram you posted is what you need to control the 2.5 TBI setup.

What did I just write?

Let us know how it turns out, the 84 could use a newer ECM

quote Originally posted by chetw77cruiser: It has to do with the injector driver setup relating to the ground side of the driver. The injector driver in the 7165 was designed to either control 1 peak/hold injector (tbi) or several saturated injectors(port). When the pins D9 and D10 are connected, the driver is set to peak and hold mode and will control the TBI injector. If D10 is grounded, the driver is set to saturated mode and will control regular port injectors. Going by the diagram you posted is what you need to control the 2.5 TBI setup. What did I just write?

It sounds like you wrote that I need to jump D9 and D10 together without grounding them to set it to TBI mode. Thanks. I'll try that.

My plan is to use the stock code (ANCZ). I was reading up on the $12P code that you've been using and I read that it doesn't support TBI... I guess that explains why all the $12P wiring diagrams that I looked at have D10 grounded and D9 unconnected.

quote Originally posted by RWDPLZ: Let us know how it turns out, the 84 could use a newer ECM

I cut the ECU connectors off yesterday, so I'm committed now... But it will take a while because I need to add in the MAT sensor. Plus I may also add ECU control of the EGR rather than disabling in the ROM.

Bob

[This message has been edited by cerulean (edited 02-18-2013).]

I do know that the $12P code will run a TBI system. I am working with a fellow who has an MG-something with the 1.5 4 cyl and a custom TBI unit on the intake. We set it to run in 4 cylinder mode. So far so good. The acceleration enrichment tables as well as a few other settings need adjusted to match up with the larger single injector, but at least it is on the road.

quote Originally posted by chetw77cruiser: I do know that the $12P code will run a TBI system. I am working with a fellow who has an MG-something with the 1.5 4 cyl and a custom TBI unit on the intake. We set it to run in 4 cylinder mode. So far so good. The acceleration enrichment tables as well as a few other settings need adjusted to match up with the larger single injector, but at least it is on the road.

I must of misread some of the threads on DelcoHacking. I'll take another look.

Thanks,
Bob

There is nothing in delcohacking about TBI using the 12P code. This is a pioneering effort on behalf of myself and another with the "Test Subject". So far things are going well.