Fast Idle problem with DS 21 ie and modern ECU replacement - Page 3
  • Register
  • Help
Page 3 of 3 First 123
Results 51 to 72 of 72
Like Tree2Likes

Thread: Fast Idle problem with DS 21 ie and modern ECU replacement

  1. #51
    Member
    Join Date
    Jan 2017
    Location
    mulgrave
    Posts
    37

    Default

    Gentlemen,

    I have been busy but not very effective.
    I have done the following
    1. Removed the 4 inlet manifold tubes (including the injectors)
    2. Replaced the 3 "old" injectors with 3 new injectors and 4 new o-rings. All the injectors are now the same.
    3. Replaced the inlet manifold gaskets
    4. Re-installed all of the above

    Car started and ran better (maybe) but now it is definitely running on only 3 cylinders.... number 4 is not working. (Removing either Number 4 spark lead or injector plug produces no change in RPM. On the remaining 3, now a very definite drop in RPM)
    There is spark at the distributor for number 4 cylinder.
    I don't know of any easy way of checking whether number 4 injector is getting power when it should (multimeter would not measure anything I assume). But as the injectors operate in pairs, it is unlikely that there is a fault in ECU except perhaps in the cable run to the injectors.

    So I assume that the problem is
    1. Faulty Number 4 spark plug (brand new that they all are, I recently installed 8 new plugs on my MG and one was faulty)
    2. Faulty Number 4 spark plug cable
    3. No power to fuel injector 4 (I assume it is not the injector both because it is brand new and also because number 4 was a problem before I replaced the old injector). Probably faulty connector or break in cable
    4. Although compression check was fine, perhaps there is a fault in piston/cylinder somewhere (I hope not!) "Daffyduck", I noted your comment about oil in the cylinder but where would oil come from? I did take the oil cap off but it made no difference

    So some more work ... plug another (old) injector into cold start line and number 4 cable and see what happens. Try new spark plug, depending on what I find, chase the cables again back to ECU. I could replace the loom to the injectors if needed but I will need to buy some more Molex connectors (do all DS's use these?)

    Regards
    ian

    Advertisement
    Blueduck (aka Ian Downie)
    1974 Citroen D Special with DS21i.e. engine and 5 speed gearbox
    MGB GT V8 B.... bullet--proof and great fun

  2. #52
    Member
    Join Date
    Jan 2017
    Location
    mulgrave
    Posts
    37

    Default

    Gentlemen,
    It would seem 9 week problem has been fixed.
    A bottle of red (pick-up only .... quality uncertain) for first who guesses what problem was.
    Cheers
    Hope this is really the end,
    Ian
    Blueduck (aka Ian Downie)
    1974 Citroen D Special with DS21i.e. engine and 5 speed gearbox
    MGB GT V8 B.... bullet--proof and great fun

  3. #53
    Administrator GreenBlood's Avatar
    Join Date
    Mar 2001
    Location
    Brisbane
    Posts
    7,567

    Icon11

    Quote Originally Posted by blueduck View Post
    Gentlemen,
    It would seem 9 week problem has been fixed.
    A bottle of red (pick-up only .... quality uncertain) for first who guesses what problem was.
    Cheers
    Hope this is really the end,
    Ian
    Dizzy cap, hairline crack. . .

    Cheers
    Chris
    74 D(very Special) >>Rejuvenation Thread<<
    C5 HDi Rouge Lucifer



    "Déesse" Roland Barthes, 'Mythologies', 1957

    The Déesse has all the characteristics of one of those objects fallen from another universe that fed the mania for novelty in the eighteenth century and a similar mania expressed by modern science fiction: the Déesse is first and foremost the new Nautilus.

    (Umberto Eco [Ed], The History of Beauty, Rizzoli, NY, 2004)

  4. #54
    Fellow Frogger! marc61's Avatar
    Join Date
    Jul 2013
    Location
    Stamford, UK
    Posts
    229

    Default

    Dodgy spark plug insulator tube?
    Cheers, Marc.

    1987 CX GTi T2 Maikonics
    1972 SM 2.7 carb
    1972 DS21 EFI

  5. #55
    Member
    Join Date
    Jan 2017
    Location
    mulgrave
    Posts
    37

    Default

    Gentlemen,
    It would seem 9 week problem has been fixed.
    A bottle of red (pick-up only .... quality uncertain) for first who guesses what problem was.
    Cheers
    Hope this is really the end,
    Ian
    Blueduck (aka Ian Downie)
    1974 Citroen D Special with DS21i.e. engine and 5 speed gearbox
    MGB GT V8 B.... bullet--proof and great fun

  6. #56
    Member
    Join Date
    Jan 2017
    Location
    mulgrave
    Posts
    37

    Default

    Hello
    2 good guesses ... close but not correct.
    Ian
    Blueduck (aka Ian Downie)
    1974 Citroen D Special with DS21i.e. engine and 5 speed gearbox
    MGB GT V8 B.... bullet--proof and great fun

  7. #57
    Fellow Frogger! mberry's Avatar
    Join Date
    Mar 2011
    Location
    victoria
    Posts
    832

    Default

    No.4 spark plug lead broken down.
    M.BERRY
    68 DS21 BVH
    70 DS21 BVH
    70 D Super
    74 D Special

  8. #58
    Member
    Join Date
    Jun 2015
    Location
    Ashburton
    Posts
    85

    Default

    Quote Originally Posted by mberry View Post
    No.4 spark plug lead broken down.
    Fitting same type of injectors

  9. #59
    Member
    Join Date
    Jun 2015
    Location
    Ashburton
    Posts
    85

    Default

    Quote Originally Posted by PeterMol View Post
    Fitting same type of injectors
    Come on Ian we need an answer. My guess is something loose

  10. #60
    Member
    Join Date
    Jan 2017
    Location
    mulgrave
    Posts
    37

    Default

    Hello
    2 good guesses ... close but not correct.
    Ian
    Blueduck (aka Ian Downie)
    1974 Citroen D Special with DS21i.e. engine and 5 speed gearbox
    MGB GT V8 B.... bullet--proof and great fun

  11. #61
    Member
    Join Date
    Jan 2017
    Location
    mulgrave
    Posts
    37

    Default

    Ok
    Dodgy Number 4 spark plug. It was new 2 months ago. Bad spark plugs seem to hunt me down.
    Only after I have put things back together and driven 50 km will I be truly convinced.
    But engine idled perfectly and accelerated perfectly. But only in garage at this stage.
    Mr Berry was close enough to get the prize
    Regards
    Ian
    GreenBlood likes this.
    Blueduck (aka Ian Downie)
    1974 Citroen D Special with DS21i.e. engine and 5 speed gearbox
    MGB GT V8 B.... bullet--proof and great fun

  12. #62
    Fellow Frogger! mberry's Avatar
    Join Date
    Mar 2011
    Location
    victoria
    Posts
    832

    Default

    Quote Originally Posted by blueduck View Post
    Ok
    Dodgy Number 4 spark plug. It was new 2 months ago. Bad spark plugs seem to hunt me down.
    Only after I have put things back together and driven 50 km will I be truly convinced.
    But engine idled perfectly and accelerated perfectly. But only in garage at this stage.
    Mr Berry was close enough to get the prize
    Regards
    Ian
    Ian,

    Great to have it sorted, perfect timing, feb fast is nearly over.
    MB
    M.BERRY
    68 DS21 BVH
    70 DS21 BVH
    70 D Super
    74 D Special

  13. #63
    Member
    Join Date
    Jan 2017
    Location
    mulgrave
    Posts
    37

    Default

    Hello all,

    Here am I thinking problem is licked

    Having driven car about 500km, the problem has suddenly returned. After changing coil and ballast resistor, in the last 200 km, I noticed, just once, a lot of smoke coming out the exhaust but it then stopped!!! Thus

    1. Car starts without trouble (even though cold start injector is blanked of due to leak)

    2. Idle is slightly rumbly but with drops of water and no obvious smoke coming out the exhaust. When car was running well there were no drops of water.

    3. Revving the engine causes missing (bucketing) and clouds of smoke coming out exhaust. This exhaust smoke has very strong smell of petrol.

    4. For no particular reason, other that the fact that it was the only item I had not checked before, I checked the temperature sensor near the distributor at the front left of block. When engine was up to temperature, it shows 450 ohms across the sensor terminals (is that the correct way to check?). I think that is what it should be. Just to see what happened, I disconnected it and car was reluctant to start

    5. Exhaust pipe itself is black and very, very sooty (no surprise given all the smoke)


    I have no idea what to check now. Has all the work I have done been to no avail?

    I know there is a mixture knob on the ECU but surely this gross problem is not going to be cured by fiddlying with that?

    Any thoughts. Should I send ECU off for checking.

    Regards
    Ian Downie
    Blueduck (aka Ian Downie)
    1974 Citroen D Special with DS21i.e. engine and 5 speed gearbox
    MGB GT V8 B.... bullet--proof and great fun

  14. #64
    Fellow Frogger! ds21bvh's Avatar
    Join Date
    Nov 2010
    Location
    Brisbane
    Posts
    511

    Default

    Sounds like cold start injector to me..sorry if youve already discussed this...
    Cheers
    Mark...

    Sent from my SM-G935F using aussiefrogs mobile app

  15. #65
    Fellow Frogger! ds21bvh's Avatar
    Join Date
    Nov 2010
    Location
    Brisbane
    Posts
    511

    Default

    Quote Originally Posted by ds21bvh View Post
    Sounds like cold start injector to me..sorry if youve already discussed this...
    Cheers
    Mark...

    Sent from my SM-G935F using aussiefrogs mobile app
    Edit I reread...that should say is it really blanked off no chance of it leaking?
    Bad injectors can leak fuel...have they been pressure tested...?


    Sent from my SM-G935F using aussiefrogs mobile app

  16. #66
    1000+ Posts
    Join Date
    Oct 2010
    Location
    Armidale
    Posts
    1,612

    Default

    I think you need to check your head gasket - compression test might be next step...

  17. #67
    Tadpole
    Join Date
    Jan 2012
    Location
    melbourne
    Posts
    27

    Default

    About the only thing left to check would be the pump and filter. Have you had a look at the fuel rail pressure while the engine is running? If the pump can't maintain 28-30psi under acceleration that would cause the engine to miss. Put a pressure gauge onto the cold start injector feed and see what happens. If all is functioning properly the pump was designed to deliver more fuel than the system can ever use and should hold the rail at 28-30psi no matter what.

    Testing the temp sensor as you described is alright, it just doesn't take into account the resistance of the wiring which should be negligible anyway. I'm surprised the car started at all without the sensor attached. In theory the car wont start if It and the MAP sensor aren't attached. Essentially the ECU will think its -30C or something like it.

    The knob on the ECU adjusts the idle mixture only. From the pics you posted it looks like someone has had a go at the ECU already adding in a variable resistor. could be the source of problems but without knowing where it's wired in it's a bit of a wild guess.

    It might be worth having the ECU looked at but I'd want to rule out absolutely everything else first, not just problems with the fuel injection.

    Failing that you may have to go looking for problems deeper in the engine.

  18. #68
    Fellow Frogger
    Join Date
    Jan 2004
    Location
    Sydney
    Posts
    7,813

    Default

    Didn't someone locally offer to loan a donor ECU to trial? That may be worth trying as a diagnostic step.
    A dry joint on the board in your own ECU could cause an intermittent problem and be hard to track down.

  19. #69
    Tadpole
    Join Date
    Jan 2012
    Location
    melbourne
    Posts
    27

    Default

    That would be me, the offer is still there if you'd like it Ian.

    Just a random thought, what is the resistance of the coil in the new injectors? I'm just wondering if it could be different enough to throw the ECU out of calibration.

  20. #70
    Member
    Join Date
    Jan 2017
    Location
    mulgrave
    Posts
    37

    Default

    Hello all.... and thanks for suggestion.

    Note.

    1. The cold start injector is definetly blocked off.

    2. The injectors are all brand new. I have not checked the injector resisitance but they are meant to be direct replacements. Would they work for 100 kilometers and the suddenly stop working and then all start working again?

    3. The car has had a complete head recondition and new head gasket 1000km ago. I did a compression test during this problem resolution and they were. No. 1 172 No.2 162 No.3 172 No.4 158. All high but even enough I would think. I will check again.

    4. The fuel filter is new about 2000km ago. I have checked the fuel pressure and it is consistently 2 bars with almost know variation. The bump has an odd vibration that comes into play after driving for 10 minutes and stops if you sop and then start engine. I have a new spare so I think I will replace it. And a new filter .... who knows

    5. Actually the car did not quite start with temperature sensor detached. It kicked a few times and that was it. And it definetly will not start when the MAP is disconnected.

    6. Faulksy, thanks for confirming offer. I might take you up on it

    Regards
    ian
    Blueduck (aka Ian Downie)
    1974 Citroen D Special with DS21i.e. engine and 5 speed gearbox
    MGB GT V8 B.... bullet--proof and great fun

  21. #71
    Member
    Join Date
    Jun 2015
    Location
    Ashburton
    Posts
    85

    Default Smoke

    Ian. When I am as following you back last Sunday the engine was smoking most of the way on and off. May help you diagnose. I would check to see if you have not diluted the oil with a whole lot of rich running just as a precaution

    Peter

  22. #72
    Member
    Join Date
    Jan 2017
    Location
    mulgrave
    Posts
    37

    Default

    Pet6er,
    Yes. I could see it some times. But no missing!
    Ian
    Blueduck (aka Ian Downie)
    1974 Citroen D Special with DS21i.e. engine and 5 speed gearbox
    MGB GT V8 B.... bullet--proof and great fun

Page 3 of 3 First 123

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

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