FRAMING JOHN DELOREAN - ON VOD www.framingjohndeloreanfilm.com
Page 2 of 4 FirstFirst 1 2 3 4 LastLast
Results 11 to 20 of 37

Thread: 3.0 Tapping Noise

  1. #11
    Senior Member
    Join Date:  Feb 2013

    Location:  FL

    Posts:    947

    My VIN:    Early

    Ran some more today, and can definitely hear intermittent and very slight misfiring pops from exhaust.
    Last edited by 81dmc; 01-21-2023 at 09:01 PM.
    Early 81 5spd conversion- DMCH Ground Effects, Double Din, Custom Instrument Cluster, QA1 Suspension, 3.0 PRV with MS3

  2. #12
    Senior Member Bitsyncmaster's Avatar
    Join Date:  May 2011

    Location:  Leonardtown, MD

    Posts:    9,000

    My VIN:    03572

    Quote Originally Posted by 81dmc View Post
    Ran some more today, and can definitely hear intermittent and very slight misfiring pops from exhaust.
    I always though my engine had the same "very slight misfiring pops". But I put some software into my idle ECU to detect a misfire which checks every two ignition pulses and triggers if that time is outside +/- 50 RPM and my engine can idle for 5 minuets without any hits. So that popping sound you hear may be something other than a misfire.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  3. #13
    Senior Member
    Join Date:  Nov 2019

    Location:  Pittsburgh, PA

    Posts:    504

    My VIN:    Yes.

    Club(s):   (DCO) (DMA) (DCUK)

    Quote Originally Posted by Bitsyncmaster View Post
    I always though my engine had the same "very slight misfiring pops". But I put some software into my idle ECU to detect a misfire which checks every two ignition pulses and triggers if that time is outside +/- 50 RPM and my engine can idle for 5 minuets without any hits. So that popping sound you hear may be something other than a misfire.
    Obligatory sewing machine sound effects.

  4. #14
    Senior Member AugustneverEnds's Avatar
    Join Date:  Jul 2012

    Location:  Syracuse, NY area

    Posts:    1,025

    My VIN:    10287

    Club(s):   (DMA)

    Does your car have a catalytic converter? Perhaps it's partially plugged? The manifold gaskets might be beginning to leak. Fun job!

    Is your EFI mapping dialed in? Maybe the mixture is slightly off.
    Nick A.

    1988 BMW 325is
    1982 DeLorean DMC-12
    1989 Jaguar XJ6

  5. #15
    Senior Member
    Join Date:  Feb 2013

    Location:  FL

    Posts:    947

    My VIN:    Early

    Quote Originally Posted by Bitsyncmaster View Post
    I always though my engine had the same "very slight misfiring pops". But I put some software into my idle ECU to detect a misfire which checks every two ignition pulses and triggers if that time is outside +/- 50 RPM and my engine can idle for 5 minuets without any hits. So that popping sound you hear may be something other than a misfire.
    Maybe you're right. I just also get some vibration when it's doing the micropops. I may run a test harness and swap to the eagle premier coil pack instead of COPs.

    Or maybe I got a bad EDIS module





    Quote Originally Posted by AugustneverEnds View Post
    Does your car have a catalytic converter? Perhaps it's partially plugged? The manifold gaskets might be beginning to leak. Fun job!

    Is your EFI mapping dialed in? Maybe the mixture is slightly off.
    Cats are new DPI high flow, and I have new manifold gaskets on order. I probably toasted the gaskets as I ran the car for about an hour then I found I forgot to tighten the header studs .

    Overall, mixture isn't done yet, but in the video, it was idling around 14 afr and 14* of timing. I messed with the AFR and it didn't effect how it was running much.
    Early 81 5spd conversion- DMCH Ground Effects, Double Din, Custom Instrument Cluster, QA1 Suspension, 3.0 PRV with MS3

  6. #16
    Senior Member
    Join Date:  Feb 2013

    Location:  FL

    Posts:    947

    My VIN:    Early

    Tried the Monaco coil pack with no change. Drained oil after 35 miles of driving. Oil had a definite dust of metal. Was a 10w30.

    I changed it to VR1 20w50 and the idle oil pressure went from 14 to 22 psi. Big improvement there. Cam lobes still look good from oil fill hole.

    I will experiment with the exhaust gasket, EDIS, and injectors next to determine my issue. Will also try running with only headers to see if that?s my vibration.
    Early 81 5spd conversion- DMCH Ground Effects, Double Din, Custom Instrument Cluster, QA1 Suspension, 3.0 PRV with MS3

  7. #17
    Administrator Ron's Avatar
    Join Date:  Jun 2011

    Location:  North GA

    Posts:    6,175

    Club(s):   (SEDOC) (DCUK)

    Did you try pulling the plug wires one at a time?

  8. #18
    Senior Member
    Join Date:  Feb 2013

    Location:  FL

    Posts:    947

    My VIN:    Early

    No change pulling injectors one at a time. Also tested injectors and spray looks good.

    I read somewhere online that the hydraulic cams are different then solid lifter cams. Anybody know if this is true?
    Early 81 5spd conversion- DMCH Ground Effects, Double Din, Custom Instrument Cluster, QA1 Suspension, 3.0 PRV with MS3

  9. #19
    Administrator Ron's Avatar
    Join Date:  Jun 2011

    Location:  North GA

    Posts:    6,175

    Club(s):   (SEDOC) (DCUK)

    Quote Originally Posted by 81dmc View Post
    No change pulling injectors one at a time. Also tested injectors and spray looks good.

    I read somewhere online that the hydraulic cams are different then solid lifter cams. Anybody know if this is true?
    Good, pulling either one should change the sound if the problem is exhaust gaskets, usually.

    Solid lift cams typically have faster ramp speeds, lift higher, and need stronger valve springs.

  10. #20
    Senior Member
    Join Date:  Feb 2013

    Location:  FL

    Posts:    947

    My VIN:    Early

    I wish there were performance cam option for the 3.0. I would?ve put a set of cams in this if that were the case.

    Hopefully most of the noise goes away with break in. I guess I?ll find out if it eats the cam or not.
    Early 81 5spd conversion- DMCH Ground Effects, Double Din, Custom Instrument Cluster, QA1 Suspension, 3.0 PRV with MS3

Page 2 of 4 FirstFirst 1 2 3 4 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •