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is this a fuel issue? or an air issue? how should i diagnose

Discussion in 'Engine/Tuning' started by P49Y-CY, Aug 5, 2019.

  1. P49Y-CY

    P49Y-CY selfie deaths ftw Established Member

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    I'm looking forward to coming down for that October mustang show you were telling me about
     
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  2. slo984now

    slo984now AKA 01yellerCobra Established Member

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    Right now I'm just hoping my car will be running in time for that.
     
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  3. P49Y-CY

    P49Y-CY selfie deaths ftw Established Member

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    i am hoping so too! i've been following your progress and that big whipple on there looks mean as hell!
     
  4. slo984now

    slo984now AKA 01yellerCobra Established Member

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    This upcoming weekend will be the big push to get it done.

    Dumb question: Have you checked your alternator voltage when the car is warm?
     
  5. P49Y-CY

    P49Y-CY selfie deaths ftw Established Member

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    no i haven't checked that, but it is a good idea. i just dropped the fuel tank to check out the pumps
     
  6. slo984now

    slo984now AKA 01yellerCobra Established Member

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    A couple summers ago I was having an issue with the alternator dropping voltage when it got hot. It caused some weird issues. Like the FPDC would max out at part throttle and the fuel pressure drop across the injectors would show 50psi. This was on my Aeroforce. Also when shifting the RPM's would drop really fast. If I wasn't paying attention it would stall. The worse case was when I was stuck in traffic in Temecula in the summer. Eventually that alternator ended up leaving me stranded in Ramona leaving my buddies place. Got it towed home (about 40 miles) and as soon as it rolled off the truck I was able to fire it up and all the readings were back to normal again.

    It might not be your issue, but just something to consider. I think that alternator had about 110K on it. I'm pretty sure it was the original.
     
  7. P49Y-CY

    P49Y-CY selfie deaths ftw Established Member

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    well the fuel pumps were not the problem and i've now swapped just about every part possible - except for the entire damn ecu and wiring harnesses lol

    it is almost like clockwork as far as how long it runs before konking out - it is just about one-half hour each time. but i'm thinking it can't be the recognized coolant temperature because it is fully warmed up long before then, and the fans come on and off many times before stalling. i may be near to having to throw in the towel on it.

    i checked the charging system and it's putting out over 14 volts even right before it stalls.

    our cars do not have an actual fuel pump relay in the fuse box like previous mustangs, is that correct? there is none listed anywhere that i can find, and i am assuming that the fpdm replaces that in our electronic returnless system?
     
  8. hotcobra03

    hotcobra03 Well-Known Member Established Member

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    Fuel pump relay is in ccrm
    Located in passenger fender
     
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  9. hotcobra03

    hotcobra03 Well-Known Member Established Member

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    Ours is non serviceable unless your an electronic geek.

    It’s a change ccrm thing for us

    I recall a few threads on bad ccrm so anything is possible

    I had looked at a friends car back in the 90s. Fuel pump relay would shut off after 5 mins of run time and car wouldn’t restart till it cooled
     
  10. P49Y-CY

    P49Y-CY selfie deaths ftw Established Member

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    Thanks, I'm gonna give it a shot! Definitely running out of parts to swap, man-o-man! lol
     
  11. P49Y-CY

    P49Y-CY selfie deaths ftw Established Member

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    well i had a really good feeling about it being the ccrm, but still no dice. car is pretty consistent about running pretty good for about a half hour, and then dying.

    since i have now changed (literally) every single part i can think of, i may be at the point of having to call in some professional diagnostic help.

    one thing is, i sure am learning a lot about working on this car! so that's a plus
     
  12. hotcobra03

    hotcobra03 Well-Known Member Established Member

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    Fuel filter you haven’t changed
    Being you said you did 30k ago
     
  13. hotcobra03

    hotcobra03 Well-Known Member Established Member

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    And what about the coils? Those you can swap full set from loaner car without killing yourself
     
  14. P49Y-CY

    P49Y-CY selfie deaths ftw Established Member

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    I did it when I dropped the tank for the fuel pumps.

    Yup I swapped those pretty early on.
     
  15. hotcobra03

    hotcobra03 Well-Known Member Established Member

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    Has any codes popped even if engine light isn’t on.

    Than what about key on engine running scan.

    I had purchased a Bosch 1350 scanner.
    This does it

    I pass basic scan but fail on running
    Gives 1 o2 code
     
  16. P49Y-CY

    P49Y-CY selfie deaths ftw Established Member

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    no codes - when i changed out the frps i accidentally turned it on without it being connected so i did get that code, but when i went to clear it no other codes came up.

    yeah now that the car is getting older and higher miles (nothing compared to yours tho lol) and i am really considering getting some more advanced diagnostic tools such as a scanner, etc.

    and thanks very much for all the advice, i really appreciate it hotcobra03!
     
  17. slo984now

    slo984now AKA 01yellerCobra Established Member

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    What about the wiggle test hotcobra03 had to do on his car? I think it was the negative cable that was broken. Maybe something is heating up and expanding then losing contact.
     
  18. hotcobra03

    hotcobra03 Well-Known Member Established Member

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    After reading over thread.

    What about compression test?

    I had mentioned it in the start.

    Something I use as diagnostics

    Fast.

    Fuel
    Air
    Spark
    Timing

    But base engine is needed and as you see with all the guys asking when buying a terminator

    Compression test is a must every time car runs funny
     
  19. P49Y-CY

    P49Y-CY selfie deaths ftw Established Member

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    no, i have not done that yet. all of the basic diagnostic stuff i realize is what should have been done first, instead of just throwing parts at it like i have been. it's like putting the cart before the horse! only reason i have been doing it this way is because i have a donor vehicle and didn't have to buy anything.

    so yeah i really need to start looking at buying or renting the basic automotive diagnostic tools such as a compression tester, leak down, fuel pressure gauge, multimeter/wiring test light, etc.

    yup that is what i have been thinking too, it sure seems like it has got to be a bad electrical connection somewhere that heats up enough to loosen? tracking it down will be the tough part tho, and that is where i guess i will have to systematically check the voltage and connection at each
     
  20. P49Y-CY

    P49Y-CY selfie deaths ftw Established Member

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    big shoutout and thanks to @bigmoose on here. he sent me a livelink software version compatible with my xcal2, it recognized everything, and i was able to get into its datalogging screen.

    as i mentioned earlier in the thread, i had a version of the old xcal2 livelink software, but it wouldn't not recognize my xcal2 device. (i also tried my xcal3 a couple weeks ago with the sct website, but also to no avail). bigmoose's xcal2 livelink was "version 6.5", and i don't think mine said that. so many thanks again, jon!

    i just ran the car for about 10 minutes and datalogged the following parameters:

    - fuel pump duty cycle: avg .28; min.21; max 1.12

    - fuel rail pr psi: avg 42; min 37; max 286

    - fuel rail pressure: avg 480; min 75; max 592

    to be honest i am not sure exactly what i am looking at, and the needles seem to be jumping all over the place. but now i have access to all the parameters available in livelink.

    can anyone recommend what other items i should check on?
     

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