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Thread: Engine Miss Under Load and With Light Throttle - Diagnosis Help Request

  1. #21
    Senior Member
    Join Date:  May 2011

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    Post

    Quote Originally Posted by DMCMW Dave View Post
    What plug gap are you running? That has much more impact on system voltage and therefore stress on the cap and rotor than plug wire resistance or coil type. .
    Stock...I'll double check it (after 10K miles) when I pull them.

    Also, the coil is hooked up correctly....

  2. #22
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    Caps and rotors do not last forever. Every time a spark jumps their gap it takes a tiny bit of metal with it. Eventually the gap gets too big for spark to jump consistently. It's no different than erosion of spark plug electrodes.

    Because they are so difficult to replace DeLorean caps and rotors sometimes get left in too long.

  3. #23
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    Post Spark Plugs Pulled

    I removed the spark plugs tonight.

    -The passenger side bank all look pretty even with a tan-ish/white color
    -The driver side bank- the middle plug and plug closest to the rear bumper were black fuel fouled(bumper one more than the middle one). The one closest to the front of the car was pretty close in comparison to the passenger side bank. The gaps were all consistent and were narrow (i didn't check them with a tool though)
    -The middle plug wire was stubborn to get off and when I tried to persuade it, the metal connector stayed on the plug and separated from the wire, ugh.
    -I was originally told to pull all of the fuel injectors, removed the linkage from the front of the engine and remove the allen bolts that hold the center section to the "W" pipe to lift the center section out and get to the distributor. I started doing this until I tried to figure out an easy way to get to the bottom two allen bolts that hold the center section to the "W" pipe.

    I then made a call and was also told that I can just remove the back hanger brackets and carefully wedge the center section up, which gives just enough room to reach the clips on the distributor cap and then slide the cap out with the wires attached and pull the rotor off.
    Does anyone have any more tricks?

    So on the way are new plugs, cap, rotor, and now I need wires. I am assuming the trouble cylinders were the two fuel fouled ones on the driver side which would narrow down to plugs, wires, or the cap/rotor.

    Any new thoughts on these latest discoveries?

    Thanks again for all of the help!!

  4. #24
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    Problem Solved-Two Problem Fuel Injectors

    I replaced all of the ignition components, including the coil (pertronix) and the problem was still present; it was not ignition related as I originally thought.
    So I pulled the fuel injectors from cylinders 5 and 6(which had-fuel fouled spark plugs) and replaced them with clean injectors. They didn't have visible dirt as much as they had black "fuel fouled soot" on them similar to the spark plugs.

    Anyway, the problem went away after replacing those injectors.

    Problem Solved.

    Thanks for all of the help everyone!!

  5. #25
    Vin3299's Doc DeLorean03's Avatar
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    My VIN:    3299

    Thank YOU for telling us what it turned out to be. This is the kind if stuff I like to see - helps those of us trying to diagnose issues something to go on. I can't stand it when someone asks for help, gets suggestions, and then fixes the problem and never tells everyone else what it was. Quite possibly my #1 pet peeve on ANY hobby forum I am a part of.
    DMCTalk.org Moderator

    Actual snippet of a conversation from Sept 2013:

    Me: Eddie, I can't wait to get the car back when you're done with it.

    Eddie: Yeah, you'll be able to give the car gas, and it won't be - like - embarrassing....

  6. #26
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    Angry Problem has started to redevelop

    Problem has started to redevelop...get a slight hesitation upon acceleration and not consistent; sometimes not noticable.
    The problem is not as bad as before, but definitely annoying.

    Could it be the fuel filter? I haven't changed it in 12K miles/2 years. I was going to wait until I upgraded to the new DMCH fuel pump/sender kit.

    Any other ideas what would cause this? Fuel accumulator? The problem happens when warmed up. Can't recall if it happens when cold. Still testing...

    Thanks for all of the help!

  7. #27
    Vin3299's Doc DeLorean03's Avatar
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    My VIN:    3299

    Did you replace all 6 injectors - or just #5 and 6?

    I'd be wiling to bet if 1-4 stayed the same, another one started to act up.

    FWIW, I haven't changed the fuel filter in 9 years.
    DMCTalk.org Moderator

    Actual snippet of a conversation from Sept 2013:

    Me: Eddie, I can't wait to get the car back when you're done with it.

    Eddie: Yeah, you'll be able to give the car gas, and it won't be - like - embarrassing....

  8. #28
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    My guess is that if you pull Injectors 5 and 6 and they are sooty looking......

    Like they were the first time around, I would first suspect the fuel lines going to those injectors bring dirty/collapsed/old preventing proper pressure (and therefore proper spray pattern leading to incomplete burning and "sooting" of the injectors), or (hopefully not) the fuel distributor being clogged somehow that 5 and 6 don't get their proper pressure leading to above..

    ...or..(and I'm spit-balling here) question why it's 5 and 6 and none of the others that feed from the same Fuel System. On my Model T, Cylinder number 1 always fouls way before 2,3, and 4 because the intake manifold is right behind the fan, and believe it or not cools the air going to #1, (actually forming ice on the intake manifold in that area). To get a proper burn, you have to adjust the carb a little rich, and it fowls the plug early.

    So, why are 5 and 6 "sooting"? Intake leak in that area? Temperature difference on that part of the head? Can you see inside the intake where the injectors drop in? Is it "sooty" compared to the others?

    ..again...just spit balling....

    Doogie

  9. #29
    Senior Member vwdmc16's Avatar
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    Ive had this same issue for the last 18 months, simply replaced my 18k mile plugs and the car hasnt run this smooth in years! Yeah easy fixes!

  10. #30
    Delorean Guru
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    I would do a compression test. You might need a valve adjustment.
    David Teitelbaum

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