EDIS 4 No spark

[olie05]

Installing an EDIS 4 on a porsche 951 and were running into some problems that may also be relevant to other people running EDIS's on Z's.

 

Here are the symptoms:

 

When looking at megatune the rpm gauge only shows engine speed while cranking on the first try.

 

There is no spark at the spark plug wires, but I bench tested the edis coils and they checked out with the spark plug wires and spark plugs we are using.

 

This leads me to believe that somehow the coil driver circuit in the EDIS module is fried. Has anyone ever heard of this happening? The module is sending an engine speed signal to the megasquirt, but the module is not sending any signal to the coils.

 

also, Edis is wired per the msnse manuals.

 

Thoughts?

[Matt Cramer]

Dead EDIS modules aren't impossible, particularly if it's a used module. They don't have a very high failure rate, but sometimes a junkyard EDIS module could very well turn out to be the part that sent the car to the junkyard.

[olie05]

Just to set my mind at ease,

 

For those of you with EDIS running on a car, are you able to obtain rpm readings after the engine has stopped from it's initial run?

 

in other words: power on->start->run-> (engine stalls or turns off without power being removed) ->restart engine (with rpms reading?)

 

I'm just curious if resetting the power to obtain RPM readings is a characteristic of EDIS that we will have to deal with in the future. As of now I'm ruling this module out as toasted.

[olie05]

I tested the module today and it turns out it's good. I guess now I'm tracking down a wiring issue.

 

Anyone have any edis advice?

 

--One thing I am wondering: If the edis is somehow not sensing the missing tooth, will it still provide a PIP signal to megasquirt but no spark to the coils?

Edited September 8, 2010 by olie05

[Matt Cramer]

Just checking - you aren't powering the EDIS module from the fuel pump relay, are you?

[olie05]

Just checking - you aren't powering the EDIS module from the fuel pump relay, are you?

 

The edis (and megasquirt) is getting its power from the main relay.

 

I'm thinking that taking it all out and bench testing it might be a good idea. This is really a strange problem. I thought EDIS was supposed to work no matter what!

 

using this diagram, http://www.megamanual.com/ms2/edis4ew.gif

 

if I probe from pin 2 to 1 on the coil pack harness I see +12v

if I probe from pin 2 to 3 on the coil pack harness I see +12v also.

If I probe 2-1 or 2-3 (coil harness) on the frequency setting on the multimeter while cranking, I get no signal.

 

That's the part that's confusing me, because I can see the cranking RPM on the screen

 

Voltage drops to about 8v during cranking. Too low?

 

I'm attaching some cranking data logs which demonstrate the no RPM reading after initial cranking. Reset is required for megasquirt to read RPM again.

 

Thanks for the diagnostic tips! Hopefully we'll find an answer soon!

datalog201009051644.zip

[cygnusx1]

Swap the two wires on the VR sensor.  Even if the colors don't match.

[olie05]

Swap the two wires on the VR sensor.  Even if the colors don't match.

 

Already tried that, and it shows the same symptoms either way.

 

I would also like to add: why do the MSNSE diagrams show pin 4 disconnected? It says IGN GND ... that sounds kind of important.

 

4 cylinder EDIS module pinout

Signal EDIS Module Terminal

PIP (EDIS output signal) 1

IDM (diagnostic signal to ECU) 2

SAW (ECU spark control signal) 3

IGN GND (signal return) 4

VRS - (crank sensor negative) 5

VRS +(crank sensor positive) 6

VRS shield (crank sensor shield) 7

VPWR (ignition switched 12 volts) 8

PWR GND 9

COIL 1 (coil drive) 10

CTO (clean tach out) 11

COIL 2 (coil drive) 12

Edited September 9, 2010 by olie05

[olie05]

Finally got to work on the car this past weekend. I took the trigger wheel off and remounted it, made sure it was centered, then did some cranking tests. Somehow the RPM signal was getting to megasquirt regardless of previous cranking history (this was not the case before).

 

I took the spark plugs out and decided to sandblast them, since the closest autoparts store was about a 30min drive from where we were.

 

Set the cranking pulsewidths very low and it fired right up.

 

Looking back, I'm guessing everything was working right the whole time, I just could not diagnose the coil signals using the multimeter's Frequency setting.

 

Thanks for all the suggestions guys!

 

..Now to create a tach signal for the autometer Tach that works with the edis module...