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  1. #11
    Join Date
    Dec 2009
    Posts
    105

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    Hi,

    With the possibility of this reply being totally worthless, here goes.
    I know quite well how the MEFI 4 system work but I am not familiar with the MEFI 5.

    In the MEFI 4 you would have a Delco EST Distributor with an Ignition Module with 2 connectors.
    The Ignition module would in fact tell the ECU that the engine is turning and if the ECU gets not signal this way it would not open the injectors.
    Granted, mine is a TBI-engine and might be totally different.

    The Ignition module would also, I think, get the coil to "fire".

    If the ignition module is faulty or the distributor shaft has lost its magnetization you would probably end up with two conditions.
    1) The injectors would not fire.
    2) The coil would provide no spark.

    One test to do would be to hook up a LED in place of one of the injectors. Crank the engine and the LED should flash.
    If it doesn't the ECU is not sending a signal to the injectors to fire and you have either a problem with distributor/ignition module or the ECU, or of course, wiring.

    With the TBI you could easily test for this by pouring a small shot of gasoline down the throat of the throttle body and the engine would run fine for 1-2 seconds.
    With an MPI I guess this is much harder...

    I think you can bypass the functionality of the Ignition Module by putting the engine in service-mode, this is what you would do when setting initial timing or base timing of the engine. Again for MEFI 4, this would be to put a paperclip between two terminals of the diacom connector. That would get the ECM to ignore the signals from the ignition module.

    Hopefully the MEFI 5 is somewhat similar and this might provide some help, otherwise, disregard this... =)

  2. #12
    Join Date
    Nov 2013
    Location
    St Georges Basin, Australia
    Posts
    61

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    Ned
    Have you cleaned the corrosion out of the inside of the dizzy cap? I'm kind of leaning toward an earthing fault. I'll have a good look over mine today and see what I find.
    Regards Carl

  3. #13
    Join Date
    Nov 2013
    Location
    St Georges Basin, Australia
    Posts
    61

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    Ned,
    Just ran an eye over mine and remembered that the ecm sould have a separate earth on it. Mine bolts to the bellhousing close to the main earth lead. Might be worth changing the wire to a new one. I just re-newed both my main cables from the battery and made a huge difference in starting. 10 years of corrosion had taken its toll on conductivity. Keep us posted.
    Regards Carl

  4. #14
    Join Date
    Nov 2009
    Posts
    9

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    Thanks for the input roosm,
    i think you are on the right track, but with the MEFI the ignition module is integrated into the coil assembly and was changed as it was thought to be the casue at first.
    We have also attached the noid light LED's in place of an injector and saw it flashing during cranking.

    Unfortunately the MEFI 5 doesn't let you put it into service mode or check the codes by connecting pins anymore which is a downer vs the ease of the 4.

  5. #15
    Join Date
    Nov 2009
    Posts
    9

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    Quote Originally Posted by carlossa View Post
    Ned,
    Just ran an eye over mine and remembered that the ecm sould have a separate earth on it. Mine bolts to the bellhousing close to the main earth lead. Might be worth changing the wire to a new one. I just re-newed both my main cables from the battery and made a huge difference in starting. 10 years of corrosion had taken its toll on conductivity. Keep us posted.
    Regards Carl
    Thanks Carl,
    i pulled the all the earth wires from the common earth point on the block on Thursday evening, gave them a good scrub cleaned the earth point itself and reassembled. I could try another wire from the ECU to that earth although we did do a test just by touching the ECM chassis and jumping it to a different point.

    Im still waiting for the promised Diacom unit so i can tackle it with all tools at my disposal on Monday.

  6. #16
    Join Date
    Nov 2009
    Posts
    9

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    Quote Originally Posted by Nedster View Post
    Hi all,
    I have a 2007 21V with the 325hp Assault engine that I haven’t been able to start for 2 months despite lots of troubleshooting and replacement parts. Between me working on it, a few mechanically minded friends and a marine mechanic with a Diacom unit we have still not managed to isolate the problem so I am hoping the wisdom of the forum can suggest some further avenues before I go crazy, and the family disowns me.

    Being in Sth Hemisphere we are boating now, so we last used it on Dec 26th and it started and stopped perfectly all morning. It was cleaned, flushed, refuelled and put into undercover storage. 2 weeks later we took it camping to a river and it just cranked and cranked but wouldn't start. Heres what we tried;
    • With limited tools we determined we had the fuel pump priming, fuel pressure at the rail, but no spark. We have not yet actually measured Fuel rail pressure (just tested it squirts from the schrader valve).
    • Visually inspecting the electrical items we could see the distributor cap and contacts were a little corroded but not cracked or damaged, however the coil looked heavily corroded so concluded it was breaking down and made a mad dash to the closest dealer 30 Miles away to get a replacement. Sadly back at camp and fitting it up - still no start
    • Next morning we came back to the dealer to get what we thought was the coil pickup for inside the distributor (now know its the camshaft angle sensor) – sadly still no start
    • We gave up on the boat, and towed it home for proper diagnosis. After downloading the MEFI5 manual we started again with multimeter in hand using the step by step guides.
    • We found no blown fuses in the engine bay or under the dash
    • We found the relays had power either side of them
    • We found the ECM had power and ground in and out when testing the 6 pin DLC and their respective ECM pins
    • We had power to the coil
    • we had continuity between the coil and the module
    • We had 5V at the CKP sensor
    • We had gnd at the CKP sensor
    • We had continuity between the CKP and the ECM
    • We tested the injectors with noid lights - all good

    At that point we thought it was probably the CKP sensor but decided to send it to the mechanic to scan rather than just throw more random money at the problem.
    After restoring all connections we gave it 1 more try and it fired up instantly. Not being on a hose at that stage and being late, we stopped the engine. A day later I set it up on the hose, started it fine, and proceeded to look for loose connections in the CKP wiring. Finding nothing I let it run for 15 minutes to flush then stopped it.

    On the next weekend, I decided to do a major check of wiring and clean rust and corrosion around the ECM and relay bank. When I removed the ECM from its plate to clean that I discovered a clot of salt build up between the plate and the ECM which I removed only to find a small hole in the back of the ECM. Looking through it with a flashlight I saw no evidence that anything had entered the hole and affected the boards inside so cleaned the area, sealed it and re-installed it.
    The boat however has never restarted. The Dealer has suggested that rarely do ECM's turn out to be the issue but it cant be excluded.
    Attachment 16904

    My mechanic (ex main dealer) who has worked on the boat for the last 4 years had it for several weeks but could pull no meaningful codes and surmised broken wires in the harness somewhere or an ECU, but couldn’t find any wires at fault.
    I took it back so I could tow it to the current dealer in case they could try swapping parts in from old stock but was told they don’t have anything left from that era so I would have to buy new anyway.

    Just to exclude it as a factor I have now replaced the CKP also – still no start.

    Since the harness is neither simple or cheap and the ECU just incredibly expensive out here I want to I be sure before parting with more cash. The codes that did appear were as below, however I’ve had other people suggest that many of those were old codes that were the result of us removing and refitting electrical plugs to test, or low battery could explain SPN66014.

    SPN636 - CKP sensor
    SPN65541 - IGN coil
    SPN65601 - TPS sensor
    SPN65602 - TPS sensor
    SPN65604 - Pedal Position sensor
    SPN65610 - TPS sensor
    SPN65701 -
    SPN66014 - Power train relay

    There is an outside chance that through the importer, I can find someone near me with a similar generation MEFI5 that I can persuade to fit my ECU to their working boat (as if their boat then starts with my ECM we can eliminate the ECM as a factor), but i'm not holding my breath waiting.

    Can anyone suggest some other areas to investigate next?

    thanks from Australia
    Tpnedster
    Hallelujah the boat is now starting consistently and i now believe there was 1 problem originally that we did fix, but introduced a 2nd issue that meant we couldn't get it to restart. I wanted to close the loop for anyone else following this.

    Steps to a solution

    I borrowed a Diacom unit to monitor the outputs i couldn't easily check with my multimeter and went back to the 1st page of the MEFI5 troubleshooting guide. One of the 1st steps is to check power and earth through the ECM by probing the connector. This time i also looked closely for corrosion on both the connector and the ECM units pins. I didn't see any corrosion, but was horrified to see 2 pins on connector J2 that were bent out of alignment so wouldn't make contact properly. I removed the ECM, checked what those pins were for (i was unused the other was in the ignition circuit) and then with really careful use of a mini screwdriver and needle nose pliers was able to straighten the pins. If you try this yourself, and get it wrong the pins do break, and you will need it repaired or replaced. Once reconnected the boat started and idled perfectly fine over multiple cycles.

    Since i was the only one who took the ECM connectors off its been my own fault and also surprising as the connectors mate really well and have a cam lock that pulls them straight down cleanly. I am usually very careful with circuit board pins as I've seen them bend before. So i guess it was just carelessness on my part that meant at some stage i have pushed it on a little too forcefully.

    Just for S and G's i put the old CKP sensor back in, and since the coil was changed (which made no difference) before i removed the ECM connectors, I'm beginning to wonder of it was just a poor connection to the CKP all along.

    If it had been at the dealers they would have done the same tests i did, finally fitted a new ECM and then said - there's your faulty ECM, hand over a seasons petrol money !!.

    Moral of the story, use a troubleshooting guide, check the obvious things first and be careful with the ECM.
    Last edited by Nedster; 03-13-2016 at 11:59 PM. Reason: readability improvements

  7. #17
    Join Date
    Nov 2013
    Location
    St Georges Basin, Australia
    Posts
    61

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    Well done Ned. The best part is.......look how much you've learnt. Looks like you'll be hitting the water this weekend,

  8. #18
    Join Date
    Nov 2009
    Posts
    9

    Default

    Thanks Carl,
    yep hopefully i can get out earlier for a shakedown test then a weekend on the water while the weather is still good.

    cheers

  9. #19
    Join Date
    Dec 2013
    Posts
    543

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    Excellent...I love it when things start working again!

  10. #20
    Join Date
    Apr 2013
    Location
    KC, MO
    Posts
    686

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    I never saw this mentioned, but did you ever check your lanyard and the switch that connects to?
    -Mike
    2006 Supra Sunsport 20V

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