Aerostar 4.0, changed coil, still has a persistant miss, ideas?

[Movin]

Sure sounds like a connector or corrosion in injector pins problem.

[chrisofna]

I have power to the injectors that are batch fired with it, lol.

[M3NTAL]

do you have power to that injector?

^

This ^

[chrisofna]

Which connector is it?

[Movin]

All the way through the injector back to the splice? special order connector just got in for a repair here, $46.oo wow.

grounding computer side of this injector with key on should turn this injector
on and a few more.

repair could be as easy as cleaning connector..wiring in new connector.

[FestYboy]

do you have power to that injector?

^

[91mcnasty]

That's always good!

[chrisofna]

Okie dokie, here is an update:

1. Tried a different computer, didn't help.
2. I can fire injector 2 (middle right, looking in engine bay) through the wire about 2 inches up from the plug.
3. It is definitely NOT firing with the computer. Oscilloscope proved that.
4. All cylinders have spark and compression.

My next test will be if I can fire the injector manually at the top of the harness where it plugs into. I feel I'm getting closer. At least I'm narrowing it down.

[Movin]

I have alldata too, lol. It makes stuff a lot more simpler than what it is.

They are really good, mine is so old it was originally put in with "floppies"
The Modis,the solaris and the old scanner all have Snap-on Troubleshooter
and having that data base can sure save time. I finally put alldata in a
big Lap top, sure helps on projects like this Aerostar.

[chrisofna]

I have alldata too, lol. It makes stuff a lot more simpler than what it is.

[Damkid]

Moved to the repair help section where it belongs

[Movin]

I usually strip what I can off the front, bungees are useful to hold things
back out of the way. I have not dropped mounts but that might make it
easier if you are using non powered ratchets.

Info...I pay for access to all manufacturers published information and
access to a data base of common problems with vehicles experienced
by techs. I did not see your year in this thread, I used '90.

[FestYboy]

it's called batch fire, my fiero has it too. that's why i asked about power to the injector.

[chrisofna]

There is about an inch between the firewall and the plenum, and the plenum has studs going through it, I don't see how it's going to come out without the engine at least lowered. It's definitely number 5, it's the only cylinder that doesn't change the miss at all when you remove the spark plug wire. It has spark and compression (120 across the board) on that cylinder. Where did you get the info that 3 injectors fire at the same time? I can't find that information anywhere.

[Movin]

The injectors are fired 3 at a time. The red wire supplies power and the tan
wire with whatever color stripe is grounded by the computer, 3 at a time.

Have you identified which cylinder is dead ?

You will need to know that so you can replace only one injector. You will
need a upper plenum gasket and patience to remove the upper plenum.

If you have to test the injectors, you can leave them clips to the fuel
rail, lift them from the lower intake and put a paper towel under each
injector then crank the engine to make them squirt fuel onto the towel

Unplug the primary of the coil and take all safety precautions with fuel.

It is kind of a drag to pull all that so you want to make sure you have
spark and compression in the dead cylinder before doing all that...I hate to
say it again, but no vacuum leaks!! either.

It is fun diagnosing stuff, keep us informed!!