Wierd thing that happens
 

I dont know if this is just my car, or all ca18et's in S12's or common overall, BUT

when i pull up to a junction etc car moving slow or stopped, idle is fine.

if im driving at around 60mph plus, then put my foot on the clutch (i.e coasting) the car wont idle, it just stalls as if i turned off the engine.

i know there is no reason to coast at 60mph but it was more a fluke, i was going along an 'A' road following a merc sports motor, at more than 60 ;) and passed a petrol garage that plod sits at, so i coasted past it so not to gain attention. but the engine just stalled so i tested till i found the speed where it starts to happen. obviously the second i raise the clutch again the engine becomes alive again without a beat.

is this meant to happen, if not what would be the most likely cause???

cheers.

dump valve maybe

cant see why that would make a difference at what speed im doing??? it idles fine anything below 60mph and my DV is a baily twin piston gp1.

Ive had this on my et and det. Have you got any exhasut blows or as tim says a dump valve fitted. Sometimes a faulty or wrong specced dump valve can cause the problem.

Give the old girl a good old service mate and check sensor plug contacts, boost hoses are all good and tight ,Also listen for hissing around the inlet at idle too(vaccum leak)

Sounds to me like a vacuum leak.

Throttle position sensor.

but all those would also make it not idle when at a junction, in normal driving it idles fine, its ONLY when the car is moving at more than 60+mph and i slip it into neutral. the only think i can think of is the amount of air being pushed into the front of the car at speed is forcing to air into the intake.

Found that a problem with most of my Nissan's (have had 4) usally happened if I were to stop quickly with out dropping thru the gears, in the end decided it was due to the fact I had put induction kit's on all off them, as problem seem to occur once it had been installed not all of them stalled but most would just drop the rev's dangerously low. Guess it's due to the way the air is delivered to the thottle body.

THAT sounds like an answer i can agree with, under normal conditions the car never ever cuts out.

mine also has a high flow filter on it.

cheers.