504 misses and won't accelerate.
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Thread: 504 misses and won't accelerate.

  1. #1
    Fellow Frogger! callipygous's Avatar
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    Default 504 misses and won't accelerate.

    Hi all,

    I'm having difficulty with my 504 turbo. I am after some suggestions as to what the problem may be. The car starts and idles fine, but it develops a miss at about 2,500RPM and when it is driven it will start to go, but about 5 seconds later it starts coughing and dying and won't accelerate any further.

    My main though is that it is a fuel problem, as if it were ignition it probably wouldn't idle as well as it does. If you're familiar with the vehicle, it runs a Ti lift pump which is regulated to about 2psi above manifold pressure via a fuel regulator with a boost reference. Now, watching the gauge that I've put on the regulator it would flicker from about 1.5 to 2.5 psi a lot. I thought that it may be a problem with the pump, so have tried another pump which seems not to flicker, but only holds about 1 psi fuel pressure. The car behaves the same no matter which pump was on it.

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    What are your thoughts? Does it sound like a fuel pump issue? If so, can I source a brand new Ti lift pump? Or should I use an entirely different pump all together? Running at 14 psi boost on the turbo, the fuel pump only needs to be able to supply fuel at a constant 16 psi, where the lift pump in the Ti is rated at about 35 psi. Should be sufficient?

    Where would I be able to get a new Ti lift pump?

    Are there other things I should check but may have overlooked?
    Peugeot 504 Intercooled T04 Turbo.

  2. #2
    Demannu-facturing! Demannu's Avatar
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    Don't be too hasty to rule out ignition. Remember that a spark will jump a gap easiest in a vacuum, and as cylinder pressure builds it gets harder for the spark to jump. It would only take a few minutes to close your spark plug gap up a bit and see if it's still misbehaving.

    Cylinder pressure is highest in the RPM range at the point where maximum torque is developed.

    What ignition system are you running (standard electronic or CDI)? What heat range plugs are you using?

    The old rule of thumb for forced induction engines was to close the gap up 0.1mm from standard for each half a bar of boost pressure, down to a minimum of 0.5mm... ie an electronic ignition 505 I think is supposed to run 1.0mm, so you would run 0.9mm at at 7psi, 0.8 at 15psi, etc etc. Points ignition cars usually only ran about 0.6mm, so there wasn't much you could do about them.
    Scotty

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  3. #3
    Fellow Frogger! callipygous's Avatar
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    I'm running an EDIS setup with a Microsquirt ECU. The plugs are Denso W25EDR14 plugs with the four surface gap electrodes that cannot be gapped. They're preset at 1.4 mm which is fine with the EDIS coil. I haven't had any issues with this setup before, but I'm not ruling out faulty plugs. I'm just in no hurry to replace them as they're fairly new and not an easy plug to come by. They don't appear to be fouled - I've had them out and cleaned them since this fault occurred but it didn't make any difference.
    Peugeot 504 Intercooled T04 Turbo.

  4. #4
    mud
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    i once had the same problem with my 505 series one, turned out the spark leads were perished and the spark was jumping through the insulation and earthing on the inside of the plug tubes

  5. #5
    1000+ Posts BIGRR's Avatar
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    Give the motor a rev in the dark and see if you can identify if there are any stray Zaps.


    Whack in an old set of plugs, set at 0.6mm and rule plug gap in/out?


    Not an aircleaner problem?


    A new Ti pump was worth a lot of $$$$$s (1992), I think one of the Volvos has same pump(?).
    Last edited by BIGRR; 25th May 2013 at 11:44 PM.
    Present fleet:-
    Peugeot 93' 205 Gti 16v
    Peugeot 73' 504 Ti from new
    Peugeot 08' 407 Hdi Coupe from new

    Previous fleet:-
    Peugeot 95' 605 Sv
    Peugeot 92' 205 Gti
    Renault 72' 16TS from new
    Renault 69' 10
    Renault 71' 10s
    Renault 68' 10 from new

    "Be reasonable do it my way!"


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    Fellow Frogger! callipygous's Avatar
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    Well, I'm pretty sure it isn't the pump or the leads. I got the new pump working properly and it made no difference to the miss. The spark plug leads aren't arcing visibly with the lights out so I can rule that out almost. I'll get the multimeter on the leads tomorrow and make sure there is continuity.

    Air cleaner problem? What could go wrong with the air cleaner?
    Peugeot 504 Intercooled T04 Turbo.

  7. #7
    1000+ Posts BIGRR's Avatar
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    Quote Originally Posted by callipygous View Post

    Air cleaner problem? What could go wrong with the air cleaner?
    :-
    Don't know!

    I have seen air cleaners that blocked that the motor would not start. It would take only 5 minutes to eliminate an air cleaner problem.
    Present fleet:-
    Peugeot 93' 205 Gti 16v
    Peugeot 73' 504 Ti from new
    Peugeot 08' 407 Hdi Coupe from new

    Previous fleet:-
    Peugeot 95' 605 Sv
    Peugeot 92' 205 Gti
    Renault 72' 16TS from new
    Renault 69' 10
    Renault 71' 10s
    Renault 68' 10 from new

    "Be reasonable do it my way!"


  8. #8
    1000+ Posts driven's Avatar
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    Have used this before

    Check out calculation site for pressure/flow rate for injector pumps
    http://www.deatschwerks.com/resource...ump-calculator

  9. #9
    Fellow Frogger! callipygous's Avatar
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    Looks good, but I'm running carbs.
    Peugeot 504 Intercooled T04 Turbo.

  10. #10
    Fellow Frogger! callipygous's Avatar
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    So far I've done as suggested. I've looked at the leads with the engine running at night and there is no visible arcing. I tested the leads also using a multimeter and can say that the resistances are all within spec of each other, so I can probably rule out leads. Lastly, I've tried another set of plugs with no difference, the car still misses. What else could it be? A faulty coil?
    Peugeot 504 Intercooled T04 Turbo.

  11. #11
    Fellow Frogger! rubyalpine's Avatar
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    The fact that it starts and idles, could possibly mean main jet(s) blocked. One more possibility to eliminate!

    Henry

  12. #12
    1000+ Posts Beano's Avatar
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    Spark plug insulators. Common problem.

  13. #13
    Fellow Frogger! callipygous's Avatar
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    I'm not running spark plug insulators. The insulator is built in to the spark plug lead and is very thick - made by NGK.

    It shouldn't be the jets as I've recently had the carbs apart and installed new jets in the past few weeks. I'm running two Purflux inline fuel filters too, so no dirt could possibly get past them. I would think. Still, the carbs will be the next thing I look at.
    Peugeot 504 Intercooled T04 Turbo.

  14. #14
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by callipygous View Post
    I'm not running spark plug insulators. The insulator is built in to the spark plug lead and is very thick - made by NGK.

    It shouldn't be the jets as I've recently had the carbs apart and installed new jets in the past few weeks. I'm running two Purflux inline fuel filters too, so no dirt could possibly get past them. I would think. Still, the carbs will be the next thing I look at.
    Just about all the obvious advice that we'd almost be embarrassed to give has been given!

    No chance that the double filter is restricting fuel flow?

    Is there a diaphragm somewhere in the carbies that might be split?

    I had a vaguely similar problem once with a Solex and the emulsion tube was missing completely. Put in another and no issues since. Where did the old one go? God alone knows.

    I'm almost emabarrassed to post but it must by now be something completely obvious, in hindsight of course.

    Good luck.
    JohnW

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  15. #15
    Fellow Frogger! callipygous's Avatar
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    I don't think it could be a problem with a double filter as the fuel pressure gauge is reading a resonable pressure atm. The two inline filters is how it is usually set up on the car - it's not something I did other than replace them with new filters in the past few months. Diaphragms - now that's an idea. I'll check all four of them today.

    Update -- checked all four diaphragms for damage but they're all fine and intact.
    Last edited by callipygous; 1st June 2013 at 12:25 PM. Reason: update
    Peugeot 504 Intercooled T04 Turbo.

  16. #16
    1000+ Posts Wildebeest's Avatar
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    Looking over JohnW's shoulder I'm with the tandem filter arrangement. Have you replaced the filters like with like?
    Volvo owner decided to go the "belt 'n braces" route, fitting an extra water trap filter to his injected 240. It didn't like it!

    Pardon my ignorance but.. R1 carburettors ?

  17. #17
    Member Ben1974504's Avatar
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    what brand of leads are you running? cause I've had problems with repco and champion leads, to me sounds like ignition timing

  18. #18
    Fellow Frogger! callipygous's Avatar
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    I'm running NGK leads. They're only a few months old so there shouldn't be any problem with them. Two filters is how Peugeot designed the fuel system in this vehicle, to run two small Purflux filters. That much is standard. As the name R1 carburettors suggest, they're carburettors of a Yamaha R1 motorcycle, four inline Mikuni CV carbs.
    Peugeot 504 Intercooled T04 Turbo.

  19. #19
    1000+ Posts Wildebeest's Avatar
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    CV carbs. Am I right in thinking they are similar in principle to the Stromberg type with diaphragms?
    Are your carbs "blow thru" or "suck thru"? Also,4 in line has me intrigued.
    Either way, could they be objecting to turbo operation ?

  20. #20
    Fellow Frogger! callipygous's Avatar
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    Objecting? I hope not. There was quite a few turbo R1 motorcycles getting around at one stage which testifies to some reliability. I never heard of people having problems with their setup. My setup is blow through. Here are some pictures of it all: http://www.aussiefrogs.com/forum/sho...d.php?t=102369
    Peugeot 504 Intercooled T04 Turbo.

  21. #21
    1000+ Posts Wildebeest's Avatar
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    Your previous post re the pitot tube to equalise carb float bowl etc pressures answered my next question.
    Nice tidy layout by the way.

  22. #22
    Fellow Frogger! callipygous's Avatar
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    If anybody is able to diagnose ignition problems based on Megasquirt log files and configuration files, here they are:
    https://dl.dropboxusercontent.com/u/...g-504turbo.log
    https://dl.dropboxusercontent.com/u/...-504-turbo.ecu

    I'm thinking it is ignition as the strobe light shows an intermittent pulse on some cylinders but not others. I'd hate to have to pull the carbs off again.
    Peugeot 504 Intercooled T04 Turbo.

  23. #23
    Fellow Frogger! stew's Avatar
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    What about a low float level on one carb? Stuck needle or float?

  24. #24
    Fellow Frogger! callipygous's Avatar
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    I'm tending to think it may be something to do with carbs. The strobe light shows differently, though. I've just replaced the coil pack but the problem still persists
    Peugeot 504 Intercooled T04 Turbo.

  25. #25
    Fellow Frogger! callipygous's Avatar
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    Found something interesting this afternoon. This only happens on two cylinders, however. What seems to be happening is when the engine is rev'd up to about 2,000 RPM, it advances normally as shown by the timing mark and strobe light. When it starts to develop a miss at about 2,300 RPM the timing goes back to about 0 degrees, and alternates between 0 degrees and where it should be on every second ignition event. Does this indicate some thing to do with a rev limiter issue? Or otherwise?
    Peugeot 504 Intercooled T04 Turbo.

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