4.6l 3V swap Injector Pulse Issues

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  1. #1

    Default 4.6l 3V swap Injector Pulse Issues

    Hi Everyone. I am doing a 4.6l 3V swap from a 2006 Mustang GT into and old truck. I have the stock harness and pcm which has been re pinned and reprogrammed with HP Tuners. PATS has been turned off, this has been confirmed.

    I can't get it to stumble sometimes but not all the time.

    I have Crank Signal and Spark while cranking.

    I have 12V to my injectors in key on and while cranking.

    When I starting cranking upon a new key cycle I get one pulse with 1 shot of fuel.

    If I connect my test light to the control side of the injector and battery positive I get one pulse while cranking then nothing.

    I have a stand alone fuel system and an adjustable regulator that is set to 42psi and it stays constant while cranking.

    I have new coils, New Plugs. Injectors do test out with a 9V battery. I have 5V reference at MAF. MAF is stock replacement.

    I have checked grounds on connector C175T and have continuity on pins 10, 47, 48, 49, 50.

    I have disconnected all injectors and ohmed them out to confirm that nothing is shorted.

    Not sure what tells the injectors to fire or what is failing in the sequence. Any help would be appreciated.

    TIA D

    - - - Updated - - -

    Sorry not sure how to edit thread. But I CAN get it to stumble randomly if I can get fuel in it.

    D

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  3. #2

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    It sounds like a fuel delivery issue. If you use a starting fluid will the engine attempt to start or just turnover w/o starting?


    Ed

  4. #3

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    Agreed. It will start with fluid. Just not sure why the PCM isn't telling the injectors to continue to pulse.

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  6. #4

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    If it will run on starter fluid then your problem is fuel delivery.

    Either the electrical harness to the injectors could be damaged, or the tune in the ECU is faulty or the ECU itself is faulty. While ECU's do die the incidence of death is relatively low in the non-starting bucket. By far the most common reason for a non-start is a faulty tune. I would try something like putting back a stock tune only upgraded for whatever size injector you are using. Give it a try and see if it starts. If it does then you need to fix a broken tune.


    Ed

  7. #5

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    I bought this set up 4 years ago and have never heard it run. I had a guy who does these swaps rework the harness and re program the ECU. I do have a new set of injectors coming fearing it was a shorted or plugged injector.

    I messaged him and he took another look at the program and said there doesn't seem to be anything out of sorts. The guy doesn't live anywhere near me and the engine is sitting in my 57 mercury truck so there is no going back to a stock tune. All parts are stock on the engine except for the CAI but I used the stock MAF. The MAF is facing the correct way and has 5V at it as well as 12V.

    I agree it is a fuel delivery issue but it's a matter of going thru some tests with a proper scan tool attached to see if we are missing anything or if a sensor is out of whack.

    I wouldn't rule out a damaged harness but it was gone over so I assume it good. Not sure what ohm values I should be looking for if I am looking for a shorted or damages harness.

    I could send the ECU to get tested and see if it is a bad unit but not 100% sure were to send it. I want to start with the cheapest and go form there if that in fact makes the most sense from a trouble shooting stand point.

    D

  8. #6

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    99% you are dealing with a bad tune. The other stuff while possible to create the problem would typically be isolated to a few injectors. Even if it affected four injectors the remaining four good injectors would run the engine — albeit rough but it would run.

    You most likely have a bad tune. Which as luck would have it turns out to be relatively good news. A visit to a competent tuning shop should be able to get you up and running with only moderate pain for the price of the tune.


    Ed

  9. #7

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    It's interesting that you say that as I had a local guy who is a tuner come over and he hooked up his laptop and HP Tuners and went thru it all and felt that it looked good. I have been tested the TPS and MAF and FPS for voltage VREF and grounds and they seem good. Still at a stand still. May have a local AutoTech electrical guy come over and have a look and give his opinion.

    Once I find the solution I will share it.

    D

  10. #8

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    Ok I have an update in that is going in the right direction. I replaced my injectors as this engine is 13 years old and has been sitting at least 4 or more years, definitely got more of a stumble out of it.

    Did a bit more reading and decided to unplug the Cam Position Sensors, she fired right up but dies after 3 secs. Fuel pressure remains constant and within factory specs. I tested my injector pulse and it seems to be more present while cranking. I think I will change my Crank Position Sensor and the Cam Position Sensors. They are $111 CAD for motorcraft brand from rockauto. Parts should arrive Friday and I will give it a shot.

    I did only get 180mVAC when back probing my Crank Position Sensor, and from what I understand I should have 500mVAC to 1VAC.

    D

  11. #9

  12. #10

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    Listening to your first video, the engine would not be able to run like that, even for such a short period of time, if the tune was bad. It may well be a number of bad sensors that just need to be replaced — even easier fix than a tune fix.


    Ed

  13. #11

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    I know. I was talking with a Ford Tech today and he mentioned maybe that the engine isn't seeing power in the run position once it fires. So just to confirm I hooked up my DMM to the relay that controls those power feeds and I consistently see 11.41VDC give or take when cranking. Lowest I saw was 10.66V and I never lost the voltage once. My process to getting this thing running at this point is. So for me it technically rules that out unless there is and internal PCM Issue.

    1) Change CKP and both CPS.
    2) Getting alternator tested to make sure the rectifier bridge isn't broken and causes weird feedback voltages to the PCM.
    3) Sending PCM out for testing to make sure it's not the issue.
    4) Ford Racing timing set with new cam phasors, chains etc. This is a very last resort.


    I did find another thread in the 2005-09 ford that 2 guys had the same issue, one never posted his resolve and the other said his PCM was bad and he replaced it and good to go.

    https://www.modularfords.com/threads...-Need-PCM-help


    https://www.modularfords.com/threads...ghlight=zzkats

    D

  14. #12

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    I recently did a 5.0 Explorer EFI swap into a '68 F100. Some of the power to the PCM is always hot (B+) and other parts are powered only in the run position. Initially I wired the run relay trigger to the accessory/run lead coming off of the ignition switch but came to find out that it lost power while the ignition switch was in the crank position. That confused the PCM greatly. The engine did a lot of what you are describing.

    Your old fender mount starter relay has 2 little wires coming in to the top. One is the starter wire and the other labelled I(?). It originally powered the coil with 12VDC while it was cranking. I took that power over and tied it into the one from the ignition switch run/accessory.
    Last edited by Nozzleman; 12-11-2019 at 10:03 PM.

  15. #13

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    I had a similar issue with a 03 Cobra swap and was chasing my tail. I found there was a crossed wire on the modified harness. I would do a point to point check on your harness.

    Also, is the ECM setup for a return type fuel system?
    Last edited by joorloop; 12-11-2019 at 10:18 PM.

  16. #14

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    Ok so CKP changed along with CPS and same result. It will only fire with both CPS unplugged. Popped off right valve cover to inspect Cam Phaser and VCT solenoid, both look to be in very good condition. Nothing seems out of sorts.


    Quote Originally Posted by Nozzleman View Post
    I recently did a 5.0 Explorer EFI swap into a '68 F100. Some of the power to the PCM is always hot (B+) and other parts are powered only in the run position. Initially I wired the run relay trigger to the accessory/run lead coming off of the ignition switch but came to find out that it lost power while the ignition switch was in the crank position. That confused the PCM greatly. The engine did a lot of what you are describing.

    Your old fender mount starter relay has 2 little wires coming in to the top. One is the starter wire and the other labelled I(?). It originally powered the coil with 12VDC while it was cranking. I took that power over and tied it into the one from the ignition switch run/accessory.
    I did connect my DMM a to confirm and had 12V to the correct pin and 12V consistent in start and run while cranking and had anywhere between 10.66V to 11.65V while cranking, no voltage was lost during or after cranking stopped.

    Quote Originally Posted by joorloop View Post
    I had a similar issue with a 03 Cobra swap and was chasing my tail. I found there was a crossed wire on the modified harness. I would do a point to point check on your harness.

    Also, is the ECM setup for a return type fuel system?
    I have been considering getting my knife out and cutting some tape to inspect. I have done some continuity and pin testing and haven't found anything strange yet. All injectors pin to correct injectors and pins as well as coils and in the correct firing order as well. But a quick inspection maybe in order before I send my PCM out for testing.

    Next test is disconnecting the alternator to see if isolating it from the PCM changes any behaviors. Just not sure why unplugging the Cam Position Sensors allows it to start to me that smells of bad wiring or PCM issue.

    Thanks for all your input!

    D
    Last edited by dman642008; 12-12-2019 at 07:26 PM. Reason: improve my grammar :)

  17. #15

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    I'm still chasing my tail on this one. I have tried another harness and ECM and have the same end result. It wants to run but it seems to fire and then dies. IF anything it seems like it gets to much fuel and floods itself out. I do have a return style fuel system what do I need to do other than turn adaptive voltage to disable? Do I need to tune my fuel rail setup? If so how do I do that?

    Engine is all stock except Airaid CAI with stock MAF.

    D
    Last edited by dman642008; 05-04-2020 at 11:43 PM.

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