Rough Idle on 505 GTI
  • Register
  • Help
Results 1 to 9 of 9
  1. #1
    Member
    Join Date
    Jan 2012
    Location
    Perth WA
    Posts
    32

    Default Rough Idle on 505 GTI

    Hello,
    This is my first post as I am currently hunting for a 504 or 505 wagon.
    I was looking at a Peugeot 505 GTI Wagon today, and although it was fairly neat when I took it for a test drive it was idling rough and was sluggish on take off. Fine when it was cruising but would start to miss again whenstopped and the revs dropped. It was an automatic and the airconditioning was 'stuck' on (you could press the off button and feel the change in revs, but it wouldn't click off).

    The owner mentioned that this was new and that it might have resulted from him just washing the car previously.

    Any ideas what might be causing this?

    Advertisement

  2. #2
    1000+ Posts bluey504's Avatar
    Join Date
    Oct 2010
    Location
    Dandenong Vic
    Posts
    1,259

    Default

    Offer him $100 and get hold of a workshop manual. Buy a set of sparkplugs and go from there!
    It's not that hard...rationaly write a list of the bleeding obvious and one at a freaking time eliminate. Lost track/count/patience of the mutliple/parallel fiddlers I've had to endure...sort out.
    20 litres of fresh 98 Octane fuel, after the sparkplug change, is step two! Then alternator condition.
    See, it's fairly easy.

  3. #3
    Fellow Frogger! Molerpa's Avatar
    Join Date
    Jul 2005
    Location
    South America, Argentina, That country that looks like hanging from the map... just about to fall...
    Posts
    492

    Default

    If it is a GTi, should be the same than my Argentinian SRi. (ZDJL)

    If so, the L-Jetronic injection is a electro-mechanical device, is not really "electronic" as it depends on the VAF Meter (Vane Air Flow Meter) which is next to the filter.
    Most of the times, needs periodic calibration.


    Is not quite hard.

    Remove the cover so you can see this (try to make it on a dust-free environment, as the carbon path can be damaged with dust as it acts as a sand-paper)



    Once you get it started, and can keep running (even though with a little "help" on the throat, slightly opening it) lose a little the bolt that holds the clamp of the wheel (red arrow) and while keeping the throttle open enough to be around 3000-3300 RPM, adjust the mixture with the wheel (green arrow)

    [Begin of short explanation]
    According to the amount of air measured by this device (moving the flap and as it is connected to the potentiometer, or resistive path with cursor that you can see) informs the ECU to calculate the injection pulse (amount of fuel)
    [end of short explanation]


    So, normally the calibration (if no Wideband sensor present in your toolbox hehehe) is this: at mid range (3000 Revs) and FIX THROTTLE (once achieved that RPM, not more movement, remains still) and you turn clockwise and counter clock wise the wheel.
    Normally, the spring loses strenght, so normally is needed to turn clockwise (usually less than half a turn is enough), but is good that you know the complete concept so you will be able to fix a messed up flow meter (if someone that does not know a sh... puts his hands on it)

    If you start turning the wheel counter clockwise, until the RPM of the engine are higher (with no alterations on the position of the throttle) and keep turning, the RPM will decrease, then start turning clockwise, the RPM will go higher, and then, if you cross that point, will be decreasing again. The best is where the max RPM are achieved, with the same throttle opening.

    once done this, fix again the wheel (green arrow) by tightening the bolt (red arrow) as the cruising mixture is about to be correct.

    Releasing now the throttle slowly, we go decreasing RPM, decreasing, decreasing...

    Should be able to idle. If it does (even on low or high revs than 800, skip the following and go to "IDLE OK"), if not, keep reading.


    If not, restart the engine, keep it at mid rpm, and start decreasing, at some RPM enough to not stall (by keeping it a little open by hand)




    IDLE OK

    Adjust idle from throttle (screw on the butterfly/throttle mechanism) to keep it on around 1200-1300 Revs, so you free your right hand.

    Now we have the engine idling (at high RPM, but is not needed any help from human!)


    the yellow arrow points to the idle mixture adjustment. This bypasses the VAF measurement to avoid its reading while idling.

    starts slowly to decrease RPM by the throttle on 100 RPM steps. example from 1300 to 1200.

    then, the allen bolt on the VAF meter (yellow arrow) unscrew it and see if the engine goes up or down on RPM, if goes down, open it... once you achieve the highest RPM with the same throttle opening is the correct. (same concept than before) then, 100 RPM lower... 1100, and again the idle ajustment on the VAF. 100 lower. 1000 now. Again adjusting to find out the higher RPM with that position of throttle. (may increase by adjusting it, is ok, as you are going to decrease by the throttle). and keep that until you are around of 800-850 RPM with the minimum throttle opening.
    The correct RPM for idle is 775 but is not good for the car. I recommend 800-850 (more 850 than 800) but is up to you.


    Once done this, do a tip in (full acceleration for a short period, around 1 and a half second) to see if it smokes too black. If it does, lose the wheel (green) with the bolt (red) and turn it a quarter clock-wise, then fix it with the bolt, and repeat operation until you find smooth and smokeless (ok, just a little grey smoke is ok, and better for performance) acceleration.

    May be needed a little tuning on the idle adjustment (of the VAF) after this.





    this is related to fuel, but if on cold is the problem only could be other things (the IAC... it does not deserve to be called IAC... is an auxiliary air box) or the Coolant Temp sensor of the L-Jetronic.


    Sorry if my bad english has helped to mess up everything, hope it was easy to understand.


    Quote Originally Posted by luthier View Post
    It is simply impractical to expect a petrol motor to get through too much water. That's why God invented diesels.

  4. #4
    1000+ Posts Wildebeest's Avatar
    Join Date
    Oct 2004
    Location
    Perth Western Australia
    Posts
    2,694

    Default

    Molerpa,
    I don't think our friend Peugeot Lover [1st post] is quite ready for what you describe.
    Go for the basics and yes, the suggested $100 offer [Bluey] sounds good.

    PS. Molerpa, your mods to the air flow meter is something we would do on early Volvos after the "newness" had worn off!

  5. #5
    Fellow Frogger! Molerpa's Avatar
    Join Date
    Jul 2005
    Location
    South America, Argentina, That country that looks like hanging from the map... just about to fall...
    Posts
    492

    Default

    Wildebeest,

    You may be right, but there is not much "technical" knowledge needed. Is more a matter of ear. I trust more in a good musician than a bad technician for this

    Anyway, the information is never too much, so this will remain here to be able to access, and indexed by the search engine, I guess...

    PS: If you're talking about worn is about the carbon path. this is not related to that, is related to the spring tension.


    Quote Originally Posted by luthier View Post
    It is simply impractical to expect a petrol motor to get through too much water. That's why God invented diesels.

  6. #6
    1000+ Posts okalford's Avatar
    Join Date
    Sep 2004
    Location
    Melbourne
    Posts
    10,967

    Default

    From experience with my 505 GTi it's always a good idea to check thoroughly for any air leaks in the hoses to the air flow meter. Even a tiny hidden crack can cause problems like you described peugeot lover and/or stalling.

    I have Haynes manuals available for both the 504 and 505 if you do require one at some stage.

    Kaye


    PS Your English is pretty good Molerpa and it's so nice to read your enthusiastic posts.
    Last edited by okalford; 21st January 2012 at 12:33 AM.
    '66 404 Wagon
    '78 504 Wagon
    '89 505 GTI S II Familiale

  7. #7
    Fellow Frogger! Molerpa's Avatar
    Join Date
    Jul 2005
    Location
    South America, Argentina, That country that looks like hanging from the map... just about to fall...
    Posts
    492

    Default

    Thanks for encouraging me to keep writing, but have on mind that you all could also be "creating a monster"

    Anyway, the final solution for the "L-Jetronic" is to weld on it a HANDLE.


    Quote Originally Posted by luthier View Post
    It is simply impractical to expect a petrol motor to get through too much water. That's why God invented diesels.

  8. #8
    Member
    Join Date
    Jan 2012
    Location
    Perth WA
    Posts
    32

    Default

    Thanks for the advice all, I will investigate further...

  9. #9
    1000+ Posts Gamma's Avatar
    Join Date
    Oct 2004
    Location
    Picton NSW
    Posts
    1,412

    Default

    +1 for Okalford.
    Pay special attention to the air bypass tubing, (its the one that runs over the thermostat housing). Also check out the ribbed sections of the main inlet hose, between the air mass sensor, (see fantastic pic above, (only adjust after going through ALL the simple things), and the hard plastic tapered bit which the crankcase breather enters into).

    A good neat 505GTI is a wise investment. Easy to work on, and you have a wealth of experenced current and previous owners to help here on AF.......

    Short of a dud smoking clapped out motor, grinding gear box, (which uses engine oil not gear oil!!!!!!) or rust, they are good for better than 500,000km.

    Drive a hard bargan, muttering about "Bloody French cars"..."hard to work on"..."expensive, hard to get bits"....."rubbish handeling"...."weird styling"....etc....etc..... Get it for bugger all..... and then enjoy. A 505 GTI, (many would contend)... is one of the best RWD French cars ever made.
    /// 1986 SII 505 GTI
    2003 T5 307 HDI
    2013 LandRover90
    Sacred cows make the best hamburger mince.
    If you run, you only die tired

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
  •