This was my first thought too, but my fsm says the z1 circuit also goes to the negative side of the coil, which confused me. Since he claims ground on that wire, and the van runs, I'm thinking on the injector circuit, the ecm toggles the (+)

 

I was being careful, perhaps in cumbersome reading something was lost:


I still have 1 bad injector.....that injector does not work...anywhere...so the swapping was moving the symptoms along with that bad injector.


BOTH injector caps were working just fine at that point...when I installed the new injector is when I lost power to injector cap #2

The new injector and old injector work on injector cap #1.

Im going to recheck my connector at that cap and read out the wiring as I agree there must be a weak link.


That makes sense and that's the way I originally stated I thought it would work...constant power with ground pulses coming in BUT
if that's the case then the 12v reading should be constant with the key on/run positions.....I dont read that at either injector housing and my grounds on pin 1 and 4 are constant to chassis even with power off to the vehicle. Again, injector cap #1 works just fine as wired

Looks like there is a constant ground to the injectors not applied ground pulses from the ASD. If the ASD goes bad wouldnt I not get anything from it instead of selective operations?

LandYacth is saying the same thing that is stated in my 90 FSM and those are the same readings I'm seeing in the van


Again I suspect the injector connector and its wiring

 

The +12v off the ASD relay is supposed go to the (-) side of the coil. Then the (+) side of the coil goes to the SMEC and is pulsed.

Still confused? Well you should be because that is all wrong.

The ASD is supposed to run to the (+) on the coil and the coil (-) is supposed to go to the SMEC and get pulsed. The repair manuals copy one another, so when a misprint such as this one shows up; they all end up with the misprint, including the Haynes book.

 

It's good to know there is a legitimate reason for my confusion.
These misprints must be good for smoke releasing activities.

 

So with these damn misprints I was looking at what should the wiring really be etc
Could the ASD be causing my issue?

 

If the ASD relay were not passing current the engine would just crank and never start.

For now, just inspect the pins receptacles under the cap, the 4 pin connector and the connections at the PCM.

Do the key dance and look for codes too

 

I have code 27 pop up when I installed the new injector....I wrote up top about that, not sure if you saw it.
Can' wait to get home and work on this

 

There are procedures listed for checking the ASD relay, Since you do have a factory service manual for your year, and there are obvious slight differences between an '88 and an '89, My input might just be even more confusing that misprints if they do indeed occur. or are corect for tbi but not for MPFI

If your Z1 corresponds to a (switched?) chassis ground, then the hots must be fed from the smec to fire the injectors.

A know alloro is more familiar with later model vans, and it is a possibility the two are different, so there are many possibilies as to what is actually correct.

I happen to be a little overloaded with my own cooling system issues right now. Feel free to bounce around ideas, if the injectors connectors prove not to be suspect, but at this point I feel unqualified to render further advice, especially with the possiiblities of misprints and incorrect wiring diagrams. I want to check the diagrams against my wiring, but can't right now. Good luck

 

That means there's a break in the injector circuit.

 

and a break I found




I just came back from driving the van around town for the last 3 1/2 hours....from bumper-to-bumper traffic to highway cruising...smooth sailing. The van drove so smoothly a few times I thought the van died at stops...just a smooth idle.

Inside injector housing #2 one of the pins was dislodged from it's center point so I wasn't getting contact with the injector. Moved it back in place, buttoned her up and she fired up smoothly.

-Vacuum is at 18in steady.....drops with throttle mash and upon letting go jumps up to about 21in then right back to 18in....perfect.
-Fuel pressure constant at 14-15psi though the rev range
-Code 27 is gone
-steady and consistent idle

A very happy camper here


Thanks to everyone that replied and a HUGE thanks to landyacht318 and alloro. You guys are really helpful in this forum and even when I used the search feature to find some diagnosis for my problems I'd see your names often in other threads. Thanks a lot!!





Eli