Idle speed HELP!!

[darreni]

Guys, yesterday i removed the airboxes on my 97 4.2 to give the throttle plates a good clean, as the car felt like it was missing a couple of clynders on the passengerside bank.
the job worked & the cerb is back in rude health, but when pulling up to junctions, between gear changes & when idling, the idle speed has increased to 2,000 rpm.
the motor sounds fantastic, but i'm not happy sitting at the lights with this idle speed.
Any ideas? the little plastic L shape peice at the back of the passenger airbox was loose, could it be this?
Thanks.
Darren.

[mlumb]

not sure if this will help but when i've had mine to pieces i have to be very careful about the routing of the throttle cable 'cos it gets a bit out of place when manually opening the throttle from under the bonnet.also the throttle stop on the drivers side only needs moving a fraction to cause a big variation in revs.could one of the butterflys have been disturbed causing the throttle to remain slightly open? it doesn't have to be much to give a 1000rpm increase in revs.

of course i could be talking rubbish.

mike.

[jamieheasman]

If it was really bunged-up and the person who serviced it last adjusted the idle mechanically then you may have created just enough airflow to get passed the
butterflies to cause this increase.

Check everthing over first, then look at setting this back down mechanically.

[joospeed]

Jamie sounds like he's hit the nail on the head. If this was the only work you did on the car, then it sounds as if this is exactly what's happened.

The L-shaped connector sounds a bit like the connection for the ambient air pressure sensor and this won't be the cause of the increased idle speed.

Joolz

[darreni]

thanks for the replys folks.
I readjusted the idle myself this morning& all now fine, & a bit more "drivable".
I'm sure Jamie was right, as the idle speed had dropped over time due to the butterflies gumming up, someone had altered the idle to compensate.
What does the air pressue sensor do?
Darren

[joospeed]

It measures the pressure downstream of the air filter and compensates if it gets blocked, or if you drive at high altitude. The effect is minimal

Joolz