Tampa 928s

I want to test for continuity for each Injector and the Maf cable back to the computers. A quick check on the Injectors shows an open acress the leads, one side goes to ground. All other connectors are common across one side of the bank I believe that 4 banks are fired at the same time what about the other bank where do I pick up this connection on the Ez for each bank?
How about the Maf pin outs what pins do I check on the Lh.

I have sent out my original Injectors to have them rebuilt, the Fords I am in question about. After all checking and double checking my power was way down and after full throttle it would idle at 1100 Rpm's. When I replaced my old Injectors I started to blow black smoke and felt I must have had a stuck inj.
The vendor is going to flow test both the Bosch and Ford to see how they differ if any. This will put to bed, are these direct drop ins for an 86. I'll let you know how it turns out if I can't get this to run right I want be going to Sitm.

JHowell37

The injectors are wired together like Christmas tree lights and if there's a break anywhere, none will work. IIRC all 8 fire at once. Whether the Ford injectors are a direct drop in or not hasn't been an issue for the majority of us. There is no connection from the EZF to the injectors. There is ONE connection from the LH to the injectors and that is pin 13 on the LH plug.

On the LH plug the pins that run the MAF are the following:
pin 8 on the LH plug goes to terminal 1 on the MAF
pin 7 on the LH plug goes to terminal 5 on the MAF
pin 6 on the LH plug goes to terminal 3 on the MAF
pin 14 on the LH plug goe to terminal 6 on the MAF
This leaves terminals 2 and 4 on the MAF unaccounted for
terminal 2 on the MAF goes to relay XXV on the central electrical panel
terminal 4 on the MAF goes to ground

Sending out your injectors and having the Fords tested are a waste of time and money. You've not tested the LH on a car that you know is in good working order. You've not tested the replacement LH on a car you know is in good working order. So you don't know if they work or not. 20+ year old solid state electronics are like old people and gold fish: sometimes they just die for no apparent reason.

John Speake

......................the injectors are all wired in parallel, not in series like Xmas lights...... each injector is around 16 ohms, so all 8 in parallel should show a couple of ohms only.

One side of the injectors goes to +12v. The other side to connected to ground for the required time intervals by the LH ECU. So there should be no path to ground when measuring with ignition off.

Tampa 928s

This is interesting one side of all my Inj go to ground.
I guess I will pull my LH off and see if it goes away.
So what you are telling me is that the 12v is constant with the Ign on and the ground is switching from the Lh is this correct?
And yes I did swap the Lh I have a spare This car ran great untill I took the intake off.
I want to make sure I completly understand the Inj wiring from what I heard this should not be grounded. I am going to lift the Neg on the Battery and test then Lh and test see if the ground goes away.

Tampa 928s

I removed battery ground and disconnected both computers and I still have one Inj pin to ground. Before I start chasing this short I need to make sure that this info on triggered ground is correct. The way this is testing the car should not even start but it runs Semi ok.

John Speake

You will have to taqke my word for it...

You must have a different connector in there......if one was short one side, then all the injectors would all be short because as I expained before, they are all connected in parallel.

Double check that you have the correct injector lead. If that has power on one side, and a short to ground on the other, then the injector would be on all the time. This might explain your very rich running ?

If you connected a lead to an inhjectors

Tampa 928s

John

I can still see ground from one pin off of the Injector connector, the battery ground is off, the Lh and Ex connectors are off. The change I did see was now the other Pin does not show continuity between all the pins it went away after disconnecting the above. How can I test for 12V with out starting the car all the Inj are removed along with the Lh ect. I maybe reading the 12v ground but should it lift the ground once everything is disconnected?

WallyP

The injector diagram is Page 97-249 in Volume VI of the Factory Workshop Manuals. Trying to repair or maintain a 928 without the manuals is very difficult...

From Terminal 13 on Plug W, there are two red/yellow wires that run to the injectors. One wire feeds injectors 1, 2, 3, & 4. The other wire feeds injectors 5, 6, 7 & 8. These wires are supplied 12 vdc by Relay XX, the Fuel Pump Relay.

From injectors 1, 2, 3 & 4, brown/red wires lead to a common junction point, buried in the harness. From injectors 5, 6, 7, & 8, brown/red wires lead to a common junction point, buried in the harness.

From these common junction points, brown/red wires lead to a common juntion point, buried in the harness.

From there, a brown/red wire leads to Terminal 13 on the LH ECU. When Terminal 13 is grounded by the LH ECU, all injectors fire.

It makes no difference whether the battery ground strap is connected or not - the injector harness should not be grounded if the ignition switch is off when checked with an Ohmmeter between the harness and the engine or chassis ground. (Earth to John, of course.)

When the engine is running, all injectors see 12 vdc on one pin, and a pulsed ground from the LH ECU on the other pin.

If one brown/red injector wire is grounded to the engine or chassis, all should be grounded, as all are hooked together.

John Speake is one of the most knowledgeable people on this Forum on the 928 injection system...

Imo000

Just to add something to John's and Wally's comments. The AIT sensor connector looks a lot like an injector connector and maybe Tampa 928 is mistaking this for an injector plug. This plug is close enough to the injector plugs that it can be easily taken as one.

Tampa 928s

First of all I do have a manueal on CD very hard to find what I need quickly. That said I have tracked down info as needed but my WSM does not just show the 85-86 so some info does not pertain.


I went out and found something interesting:
All Inj connections Show ground to frame on all the same side connector right side of 1/2 moon on connector, except for cylinder number 3 the ground is reversed on the connector.
Considering that there should be no ground from any pins seems I may have a short?
Also I checked all the injectors separately all have on r of 1/2 moon connectorcontinuity to pin 13 of the LH connector except for Cly 3 its reversed.
I chcked for ground to frame on pin 13 of the LH and it is not shorted.
This is making no sense:
Ground to frame all inj
Continuity to pin 13 from one side of connectors "right side of half moon ext # 3
No ground to frame form pin 13

Tampa 928s

One more thought:
If I am having a short on the Inj harness to ground would the car not run by allowing all the Inj to be held open therefor flooding it?

Tampa 928s

Got a call from the Inj rebuilder and he stated the following:

Orginal
One Inj leaking
All others flowed good improved flow rate by 2%
Impedence 16.5 Ohms
Flow rate 22.4 per hour

Ford:
Flow rate 25 Lb's per hour
14.9 Ohms impedence

Being shipped back as we speak:

Tampa 928s

I thought i would share this:
Zeus mentioned that I maybe getting feedback on the relays giving me a false reading on the pins showing that they are going to ground on the 12v line. I am going to remove the Ez, LH and FP relays and test tomorrow.
Feedback is welcome !

TAREK

I don't know how many variables you may have introduced to your car since the problem started, but didyou get the chance to verify that you have a good ECU and a good MAF? you're welcome to come by to Clearwater and swap MAF or ECU from my car if you need to, as long as you haven't changed any of the wires

Tarek

Tampa 928s

Tarek
Roger gave me a spair Maf and Lh I assume they are good ,as a last resort I'll let you know once all the parts are together.
Thanks