engine intermittent cuts out when stopping

hi disco1 1995 3.9v8 hi just lately when driving along then when i start to brake to stop my engine cuts out but starts straight up. its only just started to do it. its not all the time but every now and then. i did do a play and pay day not long ago and went through some deep water it did splutter but it seems to have started this problem off. i had a snorkel on. any ideas were to look .apart from this its fine,

Have a look at the speed transducer, in should be about 12 inches from the end of the speedo cable, at the gearbox end.
It gives the ecu an idea of how quickly the vehicle is moving, and more importantly, when your about to stop, so that the idle is controlled effectively.
If its bust, or full of water, what you have described can be one of the symptoms.
Its quite a simple device, just a small magnet rotating past a reed switch, so to test it just disconnect the wires and measure the resistance through it, whilst rotating the speedo cable.
Your results should switch from open circuit to closed circuit as its rotated, but i can't remember off the top of my head how many times it switches per rotation, but chances are if its bust it wont switch at all.

Let us know how you get on.

Dave.

Okay, But the 300 series doesn't have a speedo cable, and the transducer is directly screwed the the transfer box, so do u have problems with your speedo if not leave alone.

My 3.5 had similar symptoms and it was found that the crank case breather and its hose to the plenum was blocked, so much for main dealer servicing.
Clean the breather and check the hose first, just 5min job then start with the usual suspects, like electrical connections, air filter.

Will it idle at standstill

pete1987RRC said:

Will it idle at standstill

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And smoothly

yes it idles at tick over and smoothly just when im moving sometimes when i come to a stop it cuts out but starts straight away.

i don't know if this could be the problem. but i unscrewed the idle control valve out of the phlenium. i reconected it and turned the ignition on i heard it make a noise but it did not extend or retract when i turned off ignition. is it suppose to.

Had a similar problem with my past 2 '95 discos- both times was the plenum chamber. Might be worth pulling plenum and ancilieries off (be careful with throttle linkeage you will almost certainly end up with a damn spring imbedded in your hand :/ ) clean up, check for anyhing that needs fixing then reseal it when you put it back.

Not able to help with the idle control, as far as I am aware the problem with them is they make the engine rev higher at idle rather than cutting out

smudge67999 said:

i don't know if this could be the problem. but i unscrewed the idle control valve out of the phlenium. i reconected it and turned the ignition on i heard it make a noise but it did not extend or retract when i turned off ignition. is it suppose to.

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If you remove the idle control valve you might have an air leak - is teh gasket in good condition? I used RTV silicon in place of a gasket and all good. The idle control valve will not move when ignition switched off but it winds itself out when ignition turned on, that's why revs start high then drop back when you start the engine.

If you're loosing idle control first do as Discool said, check/clean breathers. Next check vac advance unit is good, if vac unit duff you essentially get an air leak. Next check the throttle potentiometer, if the base voltage is too low the engine won't idle. Check your ignition timing, if it is not advanced enough you might get stalling problems.

If it is non of the above then as already said you might need to remove the plenum and give it a good clean up then reassemble making sure there are no air leaks, split or perished hoses etc. If you do remove the plenum, remove the ram housing as well and give it all a good clean (use carb cleaner) and check for loose trumpets on the ram housing. Also make sure you clean the throttle disc and check/set the throttle disc, the measurement from the mouth of the bore to the outer edge of the disc should be within 0.5mm across the diameter of the disc - so measure distance at top then at the bottom, if the difference is more than 0.5mm you'll need to adjust the throttle disc.

failing all of that you might need to take a look at your base idle setting.

HTH

hi guys will look tomorrow thanks