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  1. #1

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    Virage 1200 Txi rebuild - MAG Cylinder not firing

    Hi All

    Firstly, greetings to everyone!
    I'm a total newb to the PWC game and this is my first post so take it easy on me please.
    I've done heaps of reading on this site and it's been a wealth of information.
    You guys got me to where I am today, but now I'm stuck on a problem.

    I kinda inherited this Virage Txi (1200 Di Ficht) not running, been sitting a a backyard on a trailer for a couple of years.
    Decided to tackle it as a bit of a father/son type learning experience and get it running.
    Mechanically there was 1 pot seized solid (PTO) - but got pretty lucky with the rest.
    Anyway, long story short, it got a full top end rebuild and I'm at the start-up stage.

    It has even compression across all 3 pots (130 psi), all 3 are also firing the plugs.
    On first start attempt it took a few minutes worth of cranking but eventually started up although it ran pretty rough.
    I pulled the plugs and 2 of them were black and sooty but the other 1 from the MAG cylinder was clean and clearly hadn't been firing.
    I swapped plugs over and tried again. The plug was OK as it now worked in the centre cylinder but the MAG was still not firing.
    Tested spark again, both visually with plug out and also with timing light and it is OK on both.

    This led me to the injector. I swapped the MAG and Centre injectors around for a test.
    The problem stayed with the MAG cylinder not firing and the Centre was OK. Therefore both injectors are OK.
    The MAG injector signal also tests OK using a timing light.
    It just doesn't seem to want to fire that cylinder.

    I was then thinking it may be an EMM problem, but the fact that it's giving me spark and injection signals on all 3 cylinders doesn't make sense either.
    I know the fuel pump is working but I haven't yet tested the return fuel pressure.
    Any help with this would be greatly appreciated.

    Cheers

    Coops

  2. #2
    martincom's Avatar
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    I'm not sure how you would test
    The MAG injector signal also tests OK using a timing light.
    . Can you elaborate?

    Based on what you conveyed, it does appear to be an EMM issue or, remotely, a wiring harness. However, let's backup and perform another test. All of the injectors are supplied power from the +45/21 VDC supply on the white/red wire. The EMM switches the ground path, from the injectors, to pulse them. Check the DC voltage on the white/red wire. It should be approximately 21VDC while cranking and 45VDC when running. You must keep everything connected when making this measurement. Do not open a connector to probe at.

    The EMMs have been known to have their output driver components fail, which would produce the symptoms you describe. The diagnostic software, Digital Wrench (DW) has a few static tests that allow you to check each injector, ignition coil and the fuel pump individually. It is really a handy set of tests, as they are checked without the engine running or cranking over, so you can hear injectors clacking and even the spark plugs firing, while installed in the cylinders! As well, you can hear the fuel pump run. So it can quickly isolate problems or excluide them in the process of elimination.

    I know we have a few members "down under" that have the diagnostic software. Of course, distance could be a factor, but I would suggest you reach out to them via the PM messaging utility of the forum. One member is Swan and another is bspanovic. Alternatively, they may have a three cylinder EMM that you could substitute for a test.

  3. #3

    Join Date
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    Hi Martincom

    I read somewhere on this site in 1 of the many forum I've trolled thru that you can test the injector signals by using an inductive timing light.
    Just by simply putting the inductive pickup of the light over the injector signal wire similar to how you would on a spark lead.
    At first I put it over both the signal wire and the white/red wire and got nothing.
    But if you seperate and just put the pickup on the signal wire without the white/red wire the light flashes away.
    After thinking about it, it makes sense since there's a supply voltage always on the white/red, the signal wire must get switched down to Gnd thru the EMM to fire the injector.
    The light must pickup this pulse.

    I have about 45V on the white/red when it's running but I've only tested back at the EMM side of the loom.
    I'm not a big fan of peircing wires and since I have to leave the injector end connected to test it's pretty difficult to get a running test at or near the injector.
    I've tested both the signal wire and the white/red wires for continuity and both check out OK. Connections look OK.
    The fact that it fires the other 2 cylinders and it runs kinda tells me that it's got the supply voltage from the EMM.
    I know it has spark on all 3. Spark looks OK. Similar on all 3, but I suppose 1 could be weak, coil pack perhaps??
    I'm pretty confident the injector is pulsing, I also tested using an auto stethoscope and I can hear it clicking. It's just pretty noisy when testing it that way and maybe I'm hearing the others.

    Yeah a working copy of DW software would be nice.....I have no idea where or how to get a hold of that.
    I'll look into the location of those members you mentioned.

    It's like the timing is out on that 1 cylinder, but I just don't see how that would be possible.
    Do you know of a way to check if fuel is actually getting injected in there?

    Cheers
    Coops

  4. #4

    Join Date
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    Hi Guys
    Turns out that the problem is with the EMM and the injector isn't getting sent a signal.
    So.....using a timing light to test injector pulses is NOT a reliable method.
    I managed to track down someone with DW and the injector test failed.
    Injector itself is fine.

    So, I did a bit of digging into the EMM.
    I read around here that the injector drivers have been known to fail.
    That's good I thought, as changing those out would be a pretty easy fix.
    Not so much, the 3 driver transistors are good.
    I swapped 2 around and the problem stayed with the MAG.
    So my question.....
    Does anyone know the upstream components that are driving these?
    Or, is there a circuit schematic of this board getting around somewhere?

    Cheers
    Coops

  5. #5
    downunder123
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    I don't think any member here would have schematics but I do know that HiPerCo has it all worked out. If you are happy to pay shipping to US and back and convert it all to $ Oz (+ the cost of repair) I am sure your EMM will be fixed, and you will be out for close to a $1000 aussie.
    I have some knowledge and experience with EMMs. Where in NSW do you live?


  6. #6

    Join Date
    Apr 2019
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    Australia NSW
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    Hi bspanovic

    Yeah, I know that Lakeside Tech would be the best solution.
    I think what he's charging to repair these things is pretty reasonable if you live in the US.
    But it hurts when you don't. It's like you said, basically get raped by the currency exchange and postal services.
    I'm on the Central Coast not far from Wyong.

    Cheers
    Coops

  7. #7
    downunder123
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    PM me if you think I can help you. I am in Sydney.
    Cheers

  8. #8
    Moderator HiPeRcO's Avatar
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    Quote Originally Posted by bspanovic View Post
    PM me if you think I can help you. I am in Sydney.
    Cheers
    I think you could probably help him, and I give you my blessing to do so

  9. #9
    downunder123
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    The southern hemisphere branch of the Lakesite Tech? BTW, I think the EMM flash memory programing worked well....will PM you the details.
    Cheers
    Quote Originally Posted by HiPeRcO View Post
    I think you could probably help him, and I give you my blessing to do so

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