Jump to content

Twisted...


geoffbeaumont
 Share

Recommended Posts

Been out laning in Shropshire with VeryDisco today. First time I've been out round there - easy lanes, but pleasant and fantastic views. I'll post some photo's when I get them off the camera.

The Range Rover managed a run down to Horsham and back on Saturday - was a bit rough and down on power, but okayish. Sunday it was running like...well, to be honest like a V8 that had been near water... :angry: Spent most of the day running on about four cylinders. The problem, at least in part, is that the old ignition coil is still there so the Hotwire system has a timing signal (I know I could get round this, but it's only supposed to be temporary...), and it's arcing really badly and interfering with all the electrical systems on the truck. I guess the surprising bit is that I've got away with it up to now - I ran the truck like this for several months after fitting EDIS before I took it off the road in June and had no problems with it at all.

The slightly surreal bit was that driving through water reduced the arcing considerably and the truck would then run fairly well for a few minutes until the coil dried out :lol:

The temporary solution we've come up with is to cable tie an old spark plug to one of the brackets, set a very small gap on it and attach it directly to the coil. Still causes some interferance but much less and the trucks running better now. We did consider grounding the coil, but we were worried it would burn out and leave us with no fuelling.

I strongly suspect there's another issue as well, but I need to get rid of the coil before I've any chance of diagnosing it. Time to finish installing the Megasquirt, I guess!

Link to comment
Share on other sites

The edis will produce a tach sygnal of its own (pin 2 IIRC) but the amplitude may not be enough to trigger the ECU. The correct fix would be to swap the resistor in the ecu to one of a lower value, but dont ask me which one it is! I had to do this to my tacho to get it work with the edis system.

If not the 5x diodes system seems to work well - thats what Nige runs!

Jon

Link to comment
Share on other sites

The edis will produce a tach sygnal of its own (pin 2 IIRC) but the amplitude may not be enough to trigger the ECU. The correct fix would be to swap the resistor in the ecu to one of a lower value, but dont ask me which one it is! I had to do this to my tacho to get it work with the edis system.

If not the 5x diodes system seems to work well - thats what Nige runs!

Jon

EDIS8 doesn't have a clean tach signal (though whether that makes any real world difference I don't know) - the tach signal has a 'handshake' pip on it every now and then to let the Ford ECU know it's still there when the engine isn't running. EDIS4 and (I think) EDIS6 have a clean tach output as well.

I don't see much point in rigging up diodes when I'm going to set the Megasquirt up to do the fuelling anyway. That's just making work!

Need to have a look and see if the Megasquirt has a suitable tach output for the LPG kit (think it does) - if not I'll try hooking that up to the EDIS tach output and see if it objects. The LPG kit can be set to use either 0-12 or 0-5V switched square wave, so there should be something I can use.

Link to comment
Share on other sites

What are you using to control the edis at the moment then? I used the Tach output on my megajolt unit which is a 12v square wave.

I cant beleive that megasquit doesnt have the same or similar.

Jon

Eh? :unsure:

The EDIS sends a timing pulse (PIP) - which as far as I know is basically a tach output - to the Megasquirt. It receives back a signal (SAW) which tells it how much advance to run. I think - but can't remember for sure - that SAW is a waveform signal. Might be confusing it with the VR sensor output though.

Megasquirt gets its timing signal from the EDIS controller, not the other way round. Can't see how this could be different with Megajolt since it's how EDIS works?

Link to comment
Share on other sites

PIP is a 12V square wave that is grounded when a coil is firing, so should give you a TACH signal for the ECU. I don't know how much current it will drive should the Lucas ECU need any.

ford_edis.png

Profile Ignition Pick-up is the term used for the signal sent from the Electronic Distributorless Ignition System (EDIS) to the Electronic Control Module.

This signal is the digitally modified signal that originated from the Crank Angle Sensor (CAS) in an Alternating Current (AC) format. The PIP signal into the ECM is a squarewave switched at 12 volts and is the ECM's reference for the engines speed and position. The PIP signal when received by the ECM can then be modified to take into account the ignitions timing advance. This returning signal to the EDIS unit is called the SAW (Spark Angle Word) signal as is in the form of a 5 volt squarewave.

Link to comment
Share on other sites

Nonnononono........

the Megajolt ECU has a "tach out" pin that is put there to drive the tacho.

So are you using the megasquit ecu in ignition only mode at the moment then? If so I'm sure it'll have a similar "tach out" function.

The 12v square wave is not enough to drive a flapper ecu even without the resistor that is normally on the end of the coil wire. Dont know about a hotwire ecu, but I'd guess it'd be the same.

The kick back from the coil firing can be as much as 50v, so the ecu is looking for a higher pulse than this.

Jon

Link to comment
Share on other sites

EDIS8 doesn't have a clean tach signal...

Need to have a look and see if the Megasquirt has a suitable tach output for the LPG kit (think it does) -

Yes it does. Pin 2 as mentioned previously.

I use it for just that, triggering the LPG (engine running) input.

Link to comment
Share on other sites

Nonnononono........

the Megajolt ECU has a "tach out" pin that is put there to drive the tacho.

So are you using the megasquit ecu in ignition only mode at the moment then? If so I'm sure it'll have a similar "tach out" function.

The 12v square wave is not enough to drive a flapper ecu even without the resistor that is normally on the end of the coil wire. Dont know about a hotwire ecu, but I'd guess it'd be the same.

The kick back from the coil firing can be as much as 50v, so the ecu is looking for a higher pulse than this.

Jon

The MS tach output has issues. It is a quite brief pulse (order of 100:1 duty cycle)

There was a request to change this to 50:50 on the MS forums in an upcoming firmware revision, due to the fcat it doesnt work with all tacho gauges. (MS SnS Extra code anyway)

Link to comment
Share on other sites

The MS tach output has issues. It is a quite brief pulse (order of 100:1 duty cycle)

There was a request to change this to 50:50 on the MS forums in an upcoming firmware revision, due to the fcat it doesnt work with all tacho gauges. (MS SnS Extra code anyway)

I'm running MSnS Extra anyway, but in that case I'll give the EDIS pin2 signal a go. I'd rather take it from the EDIS controller anyway, seeing it's sat right next to the LPG controller... Do you know what voltage the EDIS tach signal is?

Link to comment
Share on other sites

I'm running MSnS Extra anyway, but in that case I'll give the EDIS pin2 signal a go. I'd rather take it from the EDIS controller anyway, seeing it's sat right next to the LPG controller... Do you know what voltage the EDIS tach signal is?

Don't know TBH, but it works for me.

Replace the ignition coil with a relay coil.

This will remove the coil transformer effect but retain the back-emf pulse that is required by the hotwire as a Tachin signal.

jw

I disagree. A relay coil has far less inductance than an ignition coil bay a factor of 100 at least.

If it even works, it causes the same RFI problems.

Theres far more elegant solutions.

Link to comment
Share on other sites

The IDM signal present on all EDIS modules is used as the factory tach output to the ECU. This signal is used to determine the welfare of the ignition system. If a coil primary opens or does not fire, the IDM signal is not emitted, and thus the coil is faulty. The IDM signal is triggered by the flyback voltage of the coil being fired. The EDIS module processes this into a 512us pulse on the IDM line during operation. When the engine is stopped, but the Key is turned on (KOEOff), the EDIS module emits a 64us pulse every 262.144ms to indicate proper operation. Because of this, any tachometer operation from this line must filter out the 64us pulses.

IIRC its (very roughly) a 0-5v square wave

Cheers

Jon

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy