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Thread: Delorean Sputters/Bucks on acceleration wont run right "stage 2"

  1. #1
    Member
    Join Date:  Jan 2017

    Location:  Rockwall, Tx

    Posts:    96

    My VIN:    10686

    Delorean Sputters/Bucks on acceleration wont run right "stage 2"

    Alright I give with this car, I cant get it to run correctly. Heres what has been done and checked:

    Rebuilt engine - new high compression ratio pistons, rings, bearings, all sealed up, performance cams (hervey)
    Fuel pump - new pump DMCH, filter, cleaned out tank, rebuilt CPR/WUR, Rebuilt fuel distributor, new lines, cleaned injectors
    Vac lines all new, hooked up correctly, double checked multiple times
    no vac leaks, did a smoke test, the one i found at the pipe of agony was fixed
    timing is set to 13 degrees check with a timing light
    primary pressure regulator is set at 5.4 bar, control pressure is good
    has the delorean go uk exhaust with no cats
    frquency valve buzzes and has power. power in open loop and buzz in closed loop
    new plugs (delorean bosch) cap, wires, rotor (seated on correctly, checked the wire placement multiple times, all secured on the cap and plugs, not rotated 180)

    What happens-
    if you pull all of the injectors and put them in jars they all spray evenly and put out the same amount of fuel. I have noticed that they do drip a little after i release the pressure plate to go back to rest. When I "crack" the injectors to reset a base line the idle is good in open loop, the car has power and still has some hesitation, I hear a dull popping sound from the exhaust as i drive, gets worse the more gas you give it. when you let off the gas and the idle swings from 500 to 1200. the car will almost shut off unless you give it gas. you have very little movement on the mixture setting screw, to lean it shuts off to rich it shuts off

    if you attempt to hook up the o2 sensor for closed loop you cant even get the thing to run right, nor can you get it into speck with a dwell meter, the idle improves and holds at 800 ish but it drives like crap and sputters and bucks worse than open loop.

    the voltage on the dash gauge shows just above 8 with any accessory on (alternator hervey), i have charged my enersys odessy battery fully over night and it still drops. interesting thing is when in closed loop it holds better and no idle swing, when it is in open loop the idle swings with any electrical load, so badly the car will shut off

    So im at a loss here.

  2. #2
    Senior Member
    Join Date:  Jun 2011

    Posts:    4,317

    My VIN:    3937

    Sounds like you've been pretty thorough going through things. A couple thoughts (brainstorming mostly, not trying to imply these wouldn't already have been checked)...

    - With the install of the replacement fuel pump, are you certain the pressure side line from the pump is going to the correct hardline and the return hose to the other hardline?

    - With that 8 volts on your gauge... do you see it higher than that at any other time? Like up around 13 volts when you turn the key to accessories? Any reason to suspect a problem with the battery warning light in the instrument cluster? Does it come on when you turn the key to accessories? Any special wiring connections at the alternator that might have been hooked-up incorrectly?


    Sept. 81, auto, black interior

  3. #3
    Not a DeLorean Guru
    Join Date:  May 2011

    Location:  Rochester, NY

    Posts:    2,178

    My VIN:    01049

    Not super helpful to your problem, but once you get your car running correctly - 13 degrees is not enough advance for 'hot' cams in a PRV. You want at least 16, and if you can run premium fuel, go 18-20 to make the most of the cams.
    -Mike
    1981 DeLorean, Carb LS4 swap completed
    1999 Corvette, cam/headers/intake manifold, 400 rwhp
    2005 Elise, stock
    2016 Chevy Cruze

  4. #4
    Member
    Join Date:  Jan 2017

    Location:  Rockwall, Tx

    Posts:    96

    My VIN:    10686

    Yes the light comes on, gets right at 13v on the dash gauge. All the connections for the alternator are correct.

    Well Iíll advance the timing some, I am running & 93


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  5. #5
    Senior Member Bitsyncmaster's Avatar
    Join Date:  May 2011

    Location:  Leonardtown, MD

    Posts:    7,135

    My VIN:    03572

    Trouble shoot that 8 volt reading and you may fix many engine problems.

    Have you done a fuel pressure check?
    Dave M vin 03572
    http://dm-eng.weebly.com/

  6. #6
    Member
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    Location:  Rockwall, Tx

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    My VIN:    10686

    Yes 5.4 bar primary pressure


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  7. #7
    Senior Member
    Join Date:  May 2011

    Location:  Burnsville MN-Moving to Kalispell MT. in June 20111

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    cams?

    Didn't know about 16 degree advance running DPI's cam....

  8. #8
    Delorean Guru
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    Location:  Northern NJ

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    Check with your vendor on the correct base timing for ignition for the cams. I would also verify the correct timing on the cams and do a compression test. Recheck valve clearances. Check and check again the firing order. Plug all of the vacuum lines coming of the motor and see if that helps. Verify proper vacuum and mechanical ignition advance.
    David Teitelbaum

  9. #9
    Not a DeLorean Guru
    Join Date:  May 2011

    Location:  Rochester, NY

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    Quote Originally Posted by SS Spoiler View Post
    Didn't know about 16 degree advance running DPI's cam....
    You're always going to want to advance base timing with hotter cams. When I ran DPI's cams in my PRV, Josh advised me to run 18 degrees. Being EFI and able to get actual good fueling control, I was able to run 22 degrees without any pinging.
    -Mike
    1981 DeLorean, Carb LS4 swap completed
    1999 Corvette, cam/headers/intake manifold, 400 rwhp
    2005 Elise, stock
    2016 Chevy Cruze

  10. #10
    Member
    Join Date:  Jan 2017

    Location:  Rockwall, Tx

    Posts:    96

    My VIN:    10686

    I increased the base timing to 18 degrees. That seemed to just change the pitch of the noise. I did mange to run it in closed loop, got the dwell meter swing to around 20. But still when you give it gas it acts like the fuel is cutting out. A slight press on the throttle gets it driving but while driving if you give it more gas it just bucks and cuts out.

    Firing order is correct because after re assembly I drove it about 40 miles round trip on the highway and it ran great. The valves have been adjust 2 times to the factory spec.


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