Bx poor running problem - at long last FIXED!!!

[juraj]

Hi All

Some may remember I had a poor running problem on my bx, especially on very hot days (35degC+) the car would run rough then eventually die, this occurred mostly at idle, but sometimes in the most severe guise even at speed, on cooler days the problem had to be induced by a few minutes of running at idle, and even then might perhaps cause poor running but would not ultimately stop. All it often required was a rest for 10-60 seconds and it would restart.

Anyway I changed the

ignition module - 2nd hand
ignition coil - new
coolant temperature sensor - 2nd hand
spark plugs, leads, distributor cap and rotor - new
fuel filter - new and pump - 2nd hand - twice
borrowed an air flow meter and distributor off a running car and test drove.

All to no avail, the problem was still as before although the car ran better and seemed to deal with the problem more robustly.

There were only a few components left to change, oxygen sensor, throttle position switch, which seemed unlikely, the ECU and finally the one I had ruled out long before and forgotten about - the fuel pressure regulator!

Yes the pressure regulator was the problem, no fuel was being sent back to the tank and the rail was overpressurised and no doubt especially at idle when the mixture would have been very rich the oxygen sensor would have sensed this and the ECU most likely tried to lean it out to the point of poor running.

As for the heat? I suspect a colder engine can manage with a richer mixture. (??)

Anyway thanks to all those who offered help and sympathy

bye all

j