hi my sapphire is idleing very strangely,when started from cold it idles fine for a few minutes but then it suddenly drops off and the rev range goes from 300-400rpm(nearly cuts out) and back up to normal. Have replaced the ISCV with zero success. Also replaced the coil(for a group A one) new leads distributor cap, rotor arm and plugs. The car is fairly standard other than that. Have also checked the crank position sensor. Ive seen on other cosworths that they have(i think) boost control valve?? on top of the intercooler. i dont have this only a wire not connected on top of the intercooler. I think this has 3 pipe connections, one from the actuator, one to the turbo and one to the air box(replace on mine with a cone). Sometimes the car also misfires the odd time. nothing major think its just from a lack of driving has got better recently thanks to injector cleaner additive. anyone got any ideas

 

set your base idle.


car hot, unplug iscv, adjust idle to 900rpm via screw under throttle body, reconnect iscv, and idle should be stable.

 

thanks james that seems to have done the trick. When i plugged out the iscv the revs were only at 400! Any ideas about that boost controller thingy? Is it necessary?

 

yes, ideally you should have an amal valve fitted

 

Mine did this, took out the ISCV, gave it a bit of a clean and the throttle body also, been fine since.

 

cheers mate have cleaned it a couple of times since it was fitted but that didnt do anything for it. just started her up after a few days, now when shes warm tick over is perfect but when i started it she ran fine for the first 2 or 3 minutes but then hunted badly( to the point of cutting out a few times nothing new there) til she heated up. not the end of the world but annoying if you leave her to heat on her own and return to find a cold car. injectors? ecu? gremlins??

 

gremlins for sure...my car has then everytime i replace bits i take one step forward and three back

 

As JTECHSAFF says check the base idle.

This was the problem I had last week with my car, all fine now....

 

base idle is spot on now. 900rpm. Also that slight misfire has totally gone now(fingers crossed) prob unrelated anyway. Gonna drive it for the next few days n see how it goes. Thanks for the help lads. Was just starting to lose faith in henry!

 

its worth checking co is set correctly, and check fuelling on boost with a wideband

 

cheers james, is checking the co2 just basically hooking it up to an emmisions tester? Should be 1-2% ya?sorry for sounding stupid but what exactly is a wideband?

 

cheers james, is checking the co2 just basically hooking it up to an emmisions tester? Should be 1-2% ya?sorry for sounding stupid but what exactly is a wideband?

 

you will have to check with whoever wrote the software for co settings, typically its around 2% on non closed loop cars.

a wideband is a metering unit which uses a wideband lambda sensor to measure afr while driving the car. dont confuse these with narrowband gauges which are shit! lol

widebands as the name implies give you a wide band or wide range of metering, so they can read very very rich, or very very weak, whereas when a narrowband say its rich,potentially its still weak enough to melt your engine as they do not have enough scope