andy2986 Posted April 27, 2010 Share Posted April 27, 2010 Hi Guys, OK here we go. Engine is a 97 3.9V8 serp in a disco Before MJ, LPG and Petrol both running fine Converted to megajolt and am very pleased. When on petrol it runs well and stable, well happy. However, here is the problem. It wont switch over to gas when it should, (supposed to switch on revs) I interrogated the LPG system with the lap top and when the ignition is on everything works as it should, however when I turn the engine on when it fires up the LPG program crashes. I disconnected the lpg pulse wire, originally on the neg. of the coil now being fed with a 4 x diode and zener (same as the black and white EFI feed) and the lap top will run the program for about 20 secs then freeze. Im thinking it's an induced interference but not sure where to start. Ive also disconnected the MJ leaving just the Edis, same problem The plug leads are no where near any LPG parts. Are there any known sources of interference with Edis that could disturb an LPG system ? The VR sensor is wired in good quality twin screen cable. Will re-route the 4 x diode/zener cables away from the LPG pulse lead in case it's inducing interference Any pointers will be gratefully received Andy Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted April 27, 2010 Share Posted April 27, 2010 How are you connecting - serial, USB, ? I take it the LPG kit has its own ECU and software that you're talking about here? Quote Link to comment Share on other sites More sharing options...
Dave W Posted April 27, 2010 Share Posted April 27, 2010 It might be worth taking the RPM pulse from the EDIS unit output rather than via diodes etc... works fine on my Tartarini LPG system. Quote Link to comment Share on other sites More sharing options...
andy2986 Posted April 28, 2010 Author Share Posted April 28, 2010 How are you connecting - serial, USB, ? I take it the LPG kit has its own ECU and software that you're talking about here? Hi, Yes, the LPG system has its own ECU and is connected to the laptop via a usb cable, this set up has worked before and will work here until the engine is running. The mj is connected via serial and is working as it should. I only have one ecu plugged into the laptop at a time. Andy Quote Link to comment Share on other sites More sharing options...
andy2986 Posted April 28, 2010 Author Share Posted April 28, 2010 It might be worth taking the RPM pulse from the EDIS unit output rather than via diodes etc... works fine on my Tartarini LPG system. Hi, So does that mean you use just one of the four coil drivers ? ie one of either pins 8,9,11,12 from the edis? Andy Quote Link to comment Share on other sites More sharing options...
Quagmire Posted April 28, 2010 Share Posted April 28, 2010 Are you using resistive spark plugs? According to some of the MS blurb you might want to try pin2 on the EDIS module (the IDM output) to provide an RPM signal... Quote Link to comment Share on other sites More sharing options...
andy2986 Posted April 28, 2010 Author Share Posted April 28, 2010 Are you using resistive spark plugs? According to some of the MS blurb you might want to try pin2 on the EDIS module (the IDM output) to provide an RPM signal... Hi, No there not resistive plugs, pin 2 ? ive got that n/c at the mo so that would be an easy try. Cheers Andy Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted April 28, 2010 Share Posted April 28, 2010 Hi, So does that mean you use just one of the four coil drivers ? ie one of either pins 8,9,11,12 from the edis? Andy There's a specific tach output on the EDIS module as well as on the MJ ECU, I would be trying one of those TBH, I know a friend of mine is using the MJ tach output to directly drive the input to his LPG switch etc, works fine. Quote Link to comment Share on other sites More sharing options...
andy2986 Posted April 28, 2010 Author Share Posted April 28, 2010 Ok then just going out to have another go. Going to try pin 7 on the MJ first (says its a tach out) if that doesn't work going to try pin 2 on the Edis (IDM diagnostic signal to ecu, just looked on a couple of forums and apparently you can use that to drive a tacho as well) Will report back in due course. Oh ive also reloaded the pegaso software on the laptop, just incase. Thanks so far for all your replies, I do appreciate all your help so far. Andy Quote Link to comment Share on other sites More sharing options...
Dave W Posted April 28, 2010 Share Posted April 28, 2010 Hi, So does that mean you use just one of the four coil drivers ? ie one of either pins 8,9,11,12 from the edis? Andy Just use the tach output on the EDIS unit - pin 2 sounds right I'd use the EDIS tach rather than the MJ simply because it gives you a get you home option if the MJ fails. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted April 28, 2010 Share Posted April 28, 2010 EDIS-8 does not have a tach output, although some may be using the PIP signal I would advise against it as it's a low current signal to the ECU. If the MJ has a tach output then that would seem the ideal point to pick a tach signal from as you can program it to behave to suit your needs. You may need to check the internal wiring to see if it needs a pullup resistor. Quote Link to comment Share on other sites More sharing options...
andy2986 Posted April 28, 2010 Author Share Posted April 28, 2010 OK GOOD NEWS !! Ive used pin 7 on the MJ and the LPG ECU is seeing it and allowing the system to switch to LPG. Unfortunately the LPG program is still locking up on the lap top BUT it would appear initially that the system is running. once everything else is settled I will look into the Edis pin 2 option, the get you home thing if the MJ fails makes sense to me, but Im keen to get some proper maps in and sort out the map switching... Thanks for your help guys Andy (running on gas !!!) Quote Link to comment Share on other sites More sharing options...
Dave W Posted April 28, 2010 Share Posted April 28, 2010 EDIS-8 does not have a tach output, although some may be using the PIP signal I would advise against it as it's a low current signal to the ECU. If the MJ has a tach output then that would seem the ideal point to pick a tach signal from as you can program it to behave to suit your needs. You may need to check the internal wiring to see if it needs a pullup resistor. EDIS-8 does have a suitable tach signal on pin 2, as already stated, it works fine on my EDIS-8/LPG installation. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted April 28, 2010 Share Posted April 28, 2010 EDIS-8 does have a suitable tach signal on pin 2, as already stated, it works fine on my EDIS-8/LPG installation. FF had me confused on this one too, I know we had the choice when MJing a friends 4-cylinder Mazda engine, at which point I doubted myself and though it might be that it was just on EDIS4 and not on EDIS8.... Phew, not going as mad as quickly as I thought I was Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted April 28, 2010 Share Posted April 28, 2010 Well every day's a school day - collected wisdom of the MS community has it that only 4 & 6 cylinder EDIS modules have a tach output. Quote Link to comment Share on other sites More sharing options...
MikeAK Posted April 28, 2010 Share Posted April 28, 2010 Hi, Deifinatly has a tach output. I think Ford call it the IDM signal (Ignition Diagnostic Somthing or other). Its generated from the flyback voltage on the coil primaries. Its used by the the engine control ecu to diaganose faulty coils, PIP without IDM = coil not fired. On the ones I've had there is a thin (~ 1us from memory) pulse train emitted on IDM even when the engine not running (ign on), I think this is an "Im alive" signal from edis to ecu. I had to use a circuit to filter this out as the tacho I was driving didn't like it. Mike Quote Link to comment Share on other sites More sharing options...
andy2986 Posted April 28, 2010 Author Share Posted April 28, 2010 I will probably change over to the Edis one (pin 2) later on, for conveniance it was easier to use the MJ feed (pin 7) as the two ecu's are next to each other. first tests are all good though, just a few high rev gremlins to sort out.. Andy Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted April 28, 2010 Share Posted April 28, 2010 That'll be why then, as you say if it outputs a pulse train even when the engine's stopped you probably don't want to wire that straight to your LPG kit and find it injects LPG with the engine off Quote Link to comment Share on other sites More sharing options...
andy2986 Posted April 28, 2010 Author Share Posted April 28, 2010 Ah yes ! good point, think I will leave it where it is then !! Quote Link to comment Share on other sites More sharing options...
MikeAK Posted April 28, 2010 Share Posted April 28, 2010 Here's a link to a description of the tach output (IDM) signal, about halfway dwon the page. EDIS IDM Slightly different to what I said above, but I was working from memory. Mike Quote Link to comment Share on other sites More sharing options...
andy2986 Posted April 29, 2010 Author Share Posted April 29, 2010 Thought I would just add a couple of photos.... Quote Link to comment Share on other sites More sharing options...
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