Renault Fuego EFI timing
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Thread: Renault Fuego EFI timing

  1. #1
    Fellow Frogger! deja vu 25's Avatar
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    Default Renault Fuego EFI timing

    Have a puzzling problem at the moment with the timing on The Fuego EFI conversion project. After checking the valve timing and clearances approx 5 times we are pretty certain that the spacing on the exhaust and inlet valves is correct with the correct valves opening and closing based on TDC. When we start the car it has now power and backfires indicating a retardation in timing. Now the hard part, trying to advance the timing on a car with efi! It has the renault 21/25 ecu fitted and you can hear it advancing the timing when the car starts, well it sounds like it does as it hissess and whirs for a few seconds after start up. We have not fitted the o2 sensor yet as we have to get a hole cut in the exhaust manifold, or added a knock sensor. This should not affect the running initially and power loss and back fire. The car back fires upon acceleration indicating a possible retarded timing. Is there a way to advance the timing by a couple of degrees incrementally? Should or can the efi ecu be reset somehow so that it can learn the new set up? If that is possible. No, I do not have an XR25 to plug in. I know there have been a number of people that read the forum that have done this conversion before. Did anyone have these timing/ignition retardation problem....again assuming it is ignition retardation. Any help greatly appreciated.

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    Cheers - Luke

    1990 Renault 25 V6 Baccara - Gunmetal Grey
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    Hi Luke,
    I do not know the answers but here are some thoughts.

    Why do you think it is retarded ? Would not be my conclusion but not enough information to know from here. Get a timing light and see what the base timing is at idle. See if it is doing what you think it is when it starts !!

    To get somewhere on a new installation you have to guess the problem and then test it to see if it is correct. If the test is does not give the right answer then try a different test. In this case some degrees out of timing would not cause large problems.

    Have you got the plug leads in the correct holes for the direction of rotation ? I have made that mistake before more than once
    Good luck Jaahn

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    Fellow Frogger! deja vu 25's Avatar
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    Hello Jaahn
    Any thoughts are much appreciated. I know exactly what you mean - it has been a series of trial and error.
    My thinking of retarded timing mainly comes from trawling through the net and service manuals and lining up the symptoms with the possible suggested cause.
    I will go purchase a timing light this weekend and check the base timing at idle.

    I am pretty sure the plug leads are correct, but the next step is to take the dizzy cap off and see where the rotor button is pointing when the engine is at TDC on the compression stroke. The funny thing is it is very much like the plug leads are wrong, but the back firing puzzles me a little - making me think it is timing.

    Originally thought it was suspect fuel injectors but have replaced all of them with another set and tested the solenoids for decent clicking when positive is connected off and on.
    Cheers - Luke

    1990 Renault 25 V6 Baccara - Gunmetal Grey
    1974 Renault 17TS (1317) - Silver

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    1000+ Posts jo proffi's Avatar
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    I cant think of a way to consciously or otherwise alter the ignition timing on a Renix system to make the car perform like you are seeing. Sorry to say it but I think you need to check everything else, especialy the bits you have potential to bugger up.

    The TDC sensor gets its timing from the flywheel which can only fit in one position, and then the ecu choses the appropriate advance for the conditions.
    The dizy simply distributes the spark, but has no influence on when it fires.
    No knock sensor installed (or knock detected) will loose you some residual advance, so plug that in even if it is not installed in head.
    Not using knock or o2 sensor though will only take some timing off, and wont make any profound differences you will feel.
    The injectors are batch fire, so it doesn't matter how they are plugged in.

    It is not likely the renix system is playing up.
    More likely one of the the other parts....plug to igniter from ecu, igniter module, coil, lead to dizzi, dizzi (including sometimes absent carbon rod), leads to plugs and/or order, plugs.

    If you are keeping the renix system, you need an XR25 or you are realy doing the hard way. I have a spare Xr25 to sell as chance would have it.

    The XR25 will show real time data, so you can see in real time what effects the knock sensor and o2 gauge have and can instantly see when things like TPS are not working right.
    I dont think it would show a fault code for today's problem though, unless it is a dodgy signal from the TDC sensor.
    Do you have the r21 renix bible, the MR factory manual??


    Jo

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    Fellow Frogger! deja vu 25's Avatar
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    Hello Jo
    Thank you for your words of wisdom.
    Yes I thought that the old Renix system was pretty robust - never had one play up in any of my R25's despite the super high mileages they had on them.

    Must admit the dizzy is a second hand job, as is the coil.
    Would like to keep the Renix system for a while, until we can afford a nicer programmable unit.

    Good point regarding the knock sensor and o2 sensor. We did hook up the O2 sensor and stick it is the exhaust pipe to see if it made a difference. Alas it did not.
    Will source another TDC sensor and see if that makes a difference. We have changed the wires around on the TDC but makes no difference either - which I thought was odd.

    I have the R21 renix MR manual (the Aussie edition at that).

    I would be very interested in purchasing the XR25 from you as I can also use it on my R25V6 (which also needs a bit of diagnostic work).
    Are you happy to PM me with details/price?

    Regards
    Cheers - Luke

    1990 Renault 25 V6 Baccara - Gunmetal Grey
    1974 Renault 17TS (1317) - Silver

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    1000+ Posts jo proffi's Avatar
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    Quote Originally Posted by deja vu 25 View Post
    Must admit the dizzy is a second hand job, as is the coil.
    Would like to keep the Renix system for a while, until we can afford a nicer programmable unit.


    Will source another TDC sensor and see if that makes a difference.
    Regards
    Carefull wasting money on a TDC sesnsor. Clean it by all means, but there is a slim chance that the TDC sensor itself is your primary issue.
    They are robust and seem totaly sympathetic to dodgy wiring practices.

    A rotor button or dizzi issue would be far more likely though.
    If your tacho moves good, that is a good gauge of ignition pulse.

    I'll Pm you re the XR25

    Jo

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    Fellow Frogger! deja vu 25's Avatar
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    Thanks Jo
    Yes won't buy a new TDC sensor just yet - have about 3 spare from R25's and Fuegos in the shed
    Might have to check the dizzy out more thoroughly - rotor button and cap are brand spankers.

    Yes the tacho seems to move pretty well from memory - but will have to check it.

    Thanks for the PM re XR25.

    Regards
    Cheers - Luke

    1990 Renault 25 V6 Baccara - Gunmetal Grey
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    I'm not sure exactly what you've done on the motor, but it might be worth checking the position of the rotor button at TDC.
    If it's a PS model, the aux drive shaft might be out of timing causing the rotor button to be miles from the correct contact on the dist cap. That could cause misfiring anf bacfiring if its firing across the wrong contacts.
    Apart from that, Occams Razor.

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    Fellow Frogger! deja vu 25's Avatar
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    Thanks for the info Mistareno - very helpful. It was a PS model, but have now removed the PS pump etc as we have the dizzy at the back of the head instead of down on the side of the engine block. Will check that over the next day or so...fingers crossed.
    Cheers - Luke

    1990 Renault 25 V6 Baccara - Gunmetal Grey
    1974 Renault 17TS (1317) - Silver

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    Just had same problem, 90% sure it will either 1 & 4 lead swapped with 2 & 3 OR leads are 90 degrees out of phase.
    Last edited by 85Fuego; 26th November 2014 at 08:42 PM.
    jaahn likes this.

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    Fellow Frogger! deja vu 25's Avatar
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    You know the more we think about it the more it seems like the leads are out of phase and it is only firing on 2 cyls. Thanks all for the words of advice.
    Cheers - Luke

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    1974 Renault 17TS (1317) - Silver

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    Any developments?

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    Fellow Frogger! deja vu 25's Avatar
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    No not yet, been busy with work and kids, sports etc. Will hopefully have a go this weekend. Will keep this post up to date. However upon thinking about it I think we do have the firing order incorrect as we thought the rotor button spun clockwise and not anti clockwise!!! Can't believe we didn't twig to that - Sheesh!!
    Cheers - Luke

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    1000+ Posts Haakon's Avatar
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    Let me know if you're stuck, maybe a fresh pair of eyes/ears will help. Pretty familiar with Fuegos and R21 and R25s

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    1000+ Posts jo proffi's Avatar
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    Quote Originally Posted by deja vu 25 View Post
    thought the rotor button spun clockwise and not anti clockwise!!!
    It's just a matter of perspective.

    Jo

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    Fellow Frogger! deja vu 25's Avatar
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    Thanks Haakon. Much appreciated.

    Too true Jo.
    Cheers - Luke

    1990 Renault 25 V6 Baccara - Gunmetal Grey
    1974 Renault 17TS (1317) - Silver

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    Quote Originally Posted by deja vu 25 View Post
    No not yet, been busy with work and kids, sports etc. Will hopefully have a go this weekend. Will keep this post up to date. However upon thinking about it I think we do have the firing order incorrect as we thought the rotor button spun clockwise and not anti clockwise!!! Can't believe we didn't twig to that - Sheesh!!
    In that case, 2 & 3 will be crossed.
    cheers, Roger
    Once I thought I was wrong but, I was mistaken

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    Fellow Frogger! deja vu 25's Avatar
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    Yep, was the firing order! No 2 and 3 were reversed.Plugs where also fouled due to it only firing on 2 cylinders.

    Will post a video when it uploads to youtube.
    Drives soo sweetly now Pulls magnificently in third. No hesitation or splutter. Just need to get everything tidied up; such as sealing ecu and a full cooling system bleed.

    Thanks for all the help. Luke
    Last edited by deja vu 25; 8th December 2014 at 10:48 AM.
    Cheers - Luke

    1990 Renault 25 V6 Baccara - Gunmetal Grey
    1974 Renault 17TS (1317) - Silver

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    Fellow Frogger! deja vu 25's Avatar
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    Cheers - Luke

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