annoying BX poor running problem

[juraj]

Hi All

when the bx really heats up, especially in stop start city traffic on a hot day it runs really poorly under about 2000rpm, with virtually no power, but if i can manage to rev it higher than about 2500 i can get going with a big clutch slip, once moving quicker - out of traffic, the problem clears up, ie greter air flow i am assuming it cools down a bit, this never occurs when cold or warming up after a start,

i suspect the ignition module, 7 pin, between distributor and coil - but i always thought these things either work or dont, no itermittent difficulties,

any ideas ...

bye

juraj

[aerodynamica]

Also check the spark plug gaps are correct.

Module: swap it for a known good unit to check

[CitroJim]

i suspect the ignition module, 7 pin, between distributor and coil - but i always thought these things either work or dont, no itermittent difficulties,

Nope, well known for misfiring when hot. They fail often because the heatsink paste between it and its aluminium mounting plate/heatsink dries out and becomes ineffective, leading to the module overheating.

It's worth removing the module from the plate, giving the surfaces a clean and reallying a thin fim of new heatsink compound.

[juraj]

thanks jim

funny you should mention the heatsink paste cos i fitted that module about 2 yrs ago from a wrecked car, and gave it and the aluminium plate a really good clean and sand and applied NO paste at all !!!

ok will try to give it a go, and report

bye all

[citronut]

what modle BX is it, if its a carb version it will more than likely be moisture in the emulsion tubes in the carb, or auto choke messing about,

first and easyest to check is coolant level, if this is low it wont supplie enough to the wax stat on the carb for auto choke

were about are you

regards malcolm

[ellevie]

I once had a very strange heat related ignition problem which took me years to isolate. Sometimes after shopping for about half an hour the car would refuse to start no matter how long I turned the engine over even with the pedal pressed to the floor as recommended by Citroen for warm starting. The strange thing is if I opened the bonnet and sat in the car for about 3 minutes then it would start on the button, every time. I eventually traced the problem to poor connectivity in the small connector on the distributor which carries the signal from the magnetic sensor to the amplifier. I measured a high resistance of about 10 Ohms on this short cable, so I bypassed it with a pair of wires.

At one time or another I have solved ignition problems by cleaning and reseating the various low voltage connectors in the ignition circuit. The spade connectors on the coil seem to be especially troublesome. I also once traced a missing spark problem to poor connectivity on the big connector to the amplifier which I cured by spraying the contacts with WD40 and reseating a few times. I have also more than once traced a rough idling pattern and cutting out to poor low voltage ignition connectivity. Somebody on the BX forum also recently traced lack of power problems to a poor spade connection on the coil.

So the moral is, before you go throwing money at the problem, just clean and reseat all the connectors shown on the illustration below. Also, if you have a resistance meter, check for good continuity in the signal path from the distributor to the amplifier.

[juraj]

thanks for the replies

well i put some heat sink compound between the module and aluminium plate, to avail, still plays up when it heats up in traffic, but runs so well at other times, ok will continue with suggestions,

its is uel injected by the way and am in sydney australia now, bye

juraj