Diagnostics of EDIS system

[Dean924s]

Well after about 2 years of running my 924s with out issue it died this am. I had a nice walk home (about a mile) After some fast diagnosis in the parking lot it does not appear to be the MJLJr. I unplugged the unit and still no go. I checked fuel and there is plenty. I checked for spark and no joy. So this means that it is either the EDIS unit or the coil. I have replacements for both and I am just going to replace them and see what happens. However, if some one could point me to a diagnostics page for both the EDIS unit as well as the ford coil packs it would be helpful. It would also be helpful for us junkyard pickers if we could test the units in the cars before removal.

Brent, As usual you have a great product that has transformed my car from "mundane" to fun something that I look forward to driving every day.

[NITROPIXIE]

Sorry to hear your having problems, hopefully you can get it sorted soon enough.

Could also be the VR sensor??

To check the coil pack, although not a definitive test, is to continuity test the LT side (normally figure of around 1 Ohm or less) and the HT side (again aroung 1 Ohm). Basically you looking for open circuit (infinite Ohms) or short circuit (0 Ohms). Coil packs can test ok, under zero load, but not operate correctly as soon as the coil pack is under load.

To test an EDIS unit, the only way I can think of is to make your own test bed, which may utilise an Oscilloscope for exacting measurements or a more simple design to produce sparks as it would be setup in a car.

Out of interest what plugs have you running?? Did you change them when you switched to EDIS??

[Dean924s]

I don't think this is an EDIS problem. If I remove the lead from the #4 injector the car runs. Really bad but it runs. Plug in the #4 injector and it dies and will not start. I am beginning to suspect that there is something in the wiring harness between the cars computer that controlled the EFI and the injectors. I Ohmed it out and things seem ok but I can not figure it out.

[NITROPIXIE]

Ouch, sounds like you have some wigglies in your loom although a very strange one. Mind you for the age of car it can be expected. When I took ownership of one of my golfs it had no less than 20 single choc blocks dotted all around the loom, so I think I will produce my own loom in time and make it neater and more manageable for when removing the engine.

[Dean924s]

more fun. I can unplug any injector and it runs. Since there are two injector circuit from the stock Computer I am really thinking that it is the computer and not the wiring. I am going to Ohm out the harness tomorrow to check.

I took the computer and re soldered everything in it and the car worked for about 5 minutes but then died and reverted back to only running with 3 injectors hooked up.

I think the DME has gone bad. Probably the injector driver circuit.

I have been working on a programmable standalone system that I was going to be installing. It is about 90 percent done. IF the harness checked out I think I will move that forwarded.

I was also thinking that it may be the fuel pump or possibly the FPR. I wonder if it can not keep up with all four injectors. With only three attached it can. I don't know I guess I need to get a gauge and plumb it in and see what is going on.

[brentp]

Sorry Dean to hear you're having problems! And thank you for the kind words.

seems that you're getting spark? Weird how it runs with injectors unplugged. Overloaded injector drivers when all of them plugged in?

[Dean924s]

I think I figured it out:

From Clark's Garage

When the fuel pressure runs too high, the fuel injectors draw too much current causing the injector drivers in the DME computer to shut down. Disconnect on fuel injector connector and attempt to crank the engine. If the engine starts, where it would not start with all injector leads connected, the fuel pressure regulator is bad and should be replaced. Disconnecting one fuel injector plug reduces the injector driver current sufficiently to get the injector drivers to fire.

Now. I have a FPR from a turbo (951) on the shelf. I wonder if it will work in an NA car.

[NITROPIXIE]

Wow, that is interesting.

A turbo FPR should be fine as a temporary measure, as most FPR on EFI's regulate at 3 Bar max.

[Dean924s]

I was thinking about the 2.5 versus 3 bar and since you don't go in to boost on a na car it really should not matter.

I just put the and 86 951 FPR I had on the shelf in my car and it works perfectly. It is a 2.5 bar unit. The later 951's had 3 bar units.

On a side note I was getting progressively worse and worse fuel millage over the last couple weeks and I could smell it was running rich. I should have put it together.

[brentp]

A ha- thought it was something like that!