Some Advice please

[phillheth]

Evening Chaps,

I've had my 3b back from the garage today, they've changed the diff bush and VOILA!
no more drivetrain shunt.

the only thing stopping it from being the sublime monster it could be though is the following problem:

there seems to be a "hole" in the throttle at just above idle.
if i put my foot down just a touch, the revs build by a few hundred rpm, then cuts out completely, only to carry on revving

rev---cut out--rev--cutout-- and so on.

until i did the mark h mod, it struggled not to stall at idle if it wasnt warm. but so far as i know it didnt have this cut out problem..

the effective upshot of the problem is i can't pull away without a bit of a kangaroo petrol affair going on. i put my foot down to pull off, the revs cut as if the engines stalled, so i put my foot down a bit more and woof. off we go (with a bit of a jolt).

any thoughts? sorry i can't be any more technical.

[phillheth]

bump

[BrianSmith_S2]

Cold start valve at back of the block controling warm up mixture? I think its G62.... you need to do a search

Brian

[S2central.net]

I would suggest testing the throttle pot/switch and also the MAF...

Could also be an air leak.

Pull fault codes if you can.

[JP]

Unplug the lambda probe and see if the issue goes away. Mine did exactly the same when the lambda probe gave up the ghost. I spotted it straightaway as I have a wideband monitor and could see the afr go from 11 to 19 to 12 to 18 to 13 to 17 to 14 to 16 eventually settling at 14.5-15 everytime I tried to pull away. Unplugged the lambda sensor and it ran rich but stable. Bought a generic 3 wire one of ebay for £15 and soldered it onto the existing plugs and happy motoring since.

[phillheth]

cheers boys, i think i'll have a go at the lambda probe first

[Rikki Kitto]

I had similar prob turned out to be the throttle body sensor according to the garage who checked it out.

[steverrquattro]

ISV - idle stabilization valve? Here's a few links.

http://www.google.co.uk/imgres?imgurl=http://www.sjmautotechnik.com/trouble_shooting/ecupic/20vair.jpg&imgrefurl=http://www.sjmautotechnik.com/trouble_shooting/20vidle.html&h=320&w=504&sz=33&tbnid=szT-BvUH69BS5M:&tbnh=83&tbnw=130&prev=/images%3Fq%3Didle%2Bstabilization%2Bvalve&zoom=1&q=idle+stabilization+valve&usg=__Ya9xelhrYkXIVY5yInTNZ1rBzCU=&sa=X&ei=lwK2TKjVMo7X4gbphsmgDQ&ved=0CCIQ9QEwAg

http://www.20v.org/engprob.htm

[jonnaz]

does it only do it when hot? as mine does

[phillheth]

seems to do it when cold or warm.