hello all hope u can shed some light on this prob.
I have an escort cosworth that when ur past one 3rd throttle its fine ,but if ur trundeling along under one 3rd throttle it getts all jerky like it has to much fuel any ideas any body

 

Do you have a vacume hose off or an air leek, how does it idle, leave the car running and go round the engine and listen for any hissing sounds.

 

tried that it runs 2 bar boost so would here it lol
cheers

 

could be loads of things, whats the complete spec?

what plugs do you run? what gap?

it could be the spark getting blown out, or it could be something as simple as a blocked fuel filter

 

its doin it at part throttle not on boost and it just started will check filter but its a new ishh setup cheers

 

My 3 Door did this the Map Sensor packed up it was telling the ECU I was at 28 PSI all the time so it overfueled just a tad!!!!! But was obviously fine when I booted it.
Rich

 

wiil check that sounds right matey chears

 

Check the ISCV and the Lambada/hego sensors. And of course the map sensor vacum pipe.

You said you did a audio check for hissing, but that dont mean a thing.

Id say you prob most likley have a vacum leak. spray some brake/clutch cleaner/degreaser at various parts of the engine, to see it the revs climb due to sucking it in.