Citroën ZX 1.4i '93 erratic running and idling

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GrahamAntwerp
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Joined: 13 May 2005, 06:17
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Citroën ZX 1.4i '93 erratic running and idling

Post by GrahamAntwerp »

I purchased a Citroën ZX 1.4i '93 two years ago and it ran very well without problems until recently. A cooling system repair involving the head gasket, thermostat and water pump left a rather annoying problem.
There are three symptoms:
- from time to time, when idling, it suddenly starts switching back and forth from slow to fast at about 1 second intervals. An excessive dab on the accelerator is the only thing that will bring things back to normal.
- driving at constant speed, usually above 60 kph, sometimes (but not always) after just having released pressure on the accelerator, it suddenly loses power. A moment later power comes back, and this can happen several times. Again, the only remedy is to depress the clutch and rev the engine hard for a moment.
- very recently, after starting the engine from cold, it has the habit of stalling, at least during the first minute. After that, no stalling problems.
I can go for a whole day without the symptoms showing themselves, and another day it will happen several times on a single trip.
I have read about the petrol filter possibly needing replacement, but the idling problem strikes me as being electrical.
Can someone help me with the solution?
lighteninguk
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Post by lighteninguk »

right! well having a zx 1.4i 93 myself, my zx came with some of the problems you talk about... (wehhey) but i like the hobby :P
right as to the lack of power issue and having to use the clutch to get the power back to advoid the aggressive "jolt" as it suddly finds its power, my cure (although it isnt perfect its alot lot lot better):
find the throttle potentiometer which is to the right of the carb looking from the front of the car backwards, it has a 4 pinned plug pluggin into it. unplug and unscrew using appropriate screw driver, you will find the throttle potentiometer arm inside be very carefull not to bend any of the pins/contacts on this at it will cause you more trouble, and on the black plate which had the plug in it you will find four (possibly five i cant remember) black carbon like strips. on these strips you will find a build up of stuff (what ever the strips are made of) within what would be the 1st quarter of the strip from left to right, you will also notice it is warn away over this part which is from throttle useage (unadvoidable), clean this up, i used cotton buds, but someone might suggest a good spirit which would clean this up properly, but for me i justed used cotton buds and made sure i didnt leave any threads behind. clean up the arm inside the throttle potentiometer again with cotton buds minding not to bend them of course. then once all done, place the black plate back onto the throttle housing as it was before ensuring the seal is in its groove on the plate AND that the plate is in the exact same posistion it was in before.
screw up and i personnally put some nut lock on it to ensure it stayed put until next time.
Also whilst i did this i gave the idle control motor a service, this is the unit to the front of the car on the carb housing, this also has a four pinned plug, unscrew from the throttle housing (4 screws, 2 in very awkward places) and take it to your work bench. once at the work bench, find a way to unclip all the tags (theres quite a few as you will find) to take the unit apart. once inside you will find a small motor which opperates a "worm" screw to adjust the rod which changes the throttle posistion. inside the rod you will find two metal contacts which rub against the central contact. you will find on the places where they touch the central contact that it is slightly oily making proper contact not possible. clean these up, again i used cotton buds, to make the contacts shiney again. place the contacts backinto place again, and ensure the seal is where it was before and clip back together. place the unit back where it was on the throttle body, ensuring the rod is properly place on the throttle cam which has the throttle cable attacted to it.
if your not too confident with giving the idle control a once over you can buy them for 50 or so squids £ or buy a used once (which might be as bad as yours if it was the reason for scrapping) from a scrappy.
The car has never stalled for me, so i havent had that fun yet, although i think that problem could be caused by the same thing as what was causing the loss of power sympton.
As for the idling, i have had that problem since i had the car, and havent been able to cure it. after doing what i did above it still existed, but not as bad, i then replaced the dash blubs so i had the battery disconnected for 2 nights (had to wait for my LED bulbs to be deliverd.... doh!), when the battery was reconnected the car drove terribly because the ECU had forgotten all its little personal memories on how to drive, but after driving around for a while probably 10 miles the car learnt how to drive and is Much better, but the idle problem does still crop up when its nicely warmed up.
i have had a niggle it could be due to my head gasket which i think has gone, due to oil in coolant, and slight leak on engine, and i am just working how bad a job it is to do (i had to wait to think as i had loads of University work to do).
hope this helps!! PM, Email or just plainly reply if you need anything else.
rashmore
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Post by rashmore »

Brother had similar problem, tho his car is now completely dead (off road excursion - body panel damage = write off)
Car would start and rev a little high, then after a while would start and rev very hard.throttle idle box as mentioned above - he paid £20 from a scrap. Think (not sure) he still has the car in drive if want me to ask....simple job to swap
GrahamAntwerp
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Joined: 13 May 2005, 06:17
Location: Belgium
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Post by GrahamAntwerp »

Thank you Lightening - or should I say Enlightening! I can see that I have my work cut out for this weekend! (Whitsun still has a Bank Holiday over here in Belgium). Mind you, makes me long for the good old days of servicing SU carbs (Morris 1000, Morris 1100, Morris 1300, Mini) - you knew where you were with them!
Thanks for the offer, Rashmore - I'll try cleaning the parts first and then see what happens.
To be continued!!
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