Thread: V8i rubbish idling.

I had thought I'd got on top of this back in June when I replaced the Idle Air Control Valve with a new one & adjusted the pintle as per their instructions. Has been fine but yesterday & today it was crap again. WTF!

Got home & thought I'd start by removing the valve & giving it an internal clean. Socket on, start to loosen & bugger me, the motor came away from the threaded section which was still stuck in the plate. Inspected the shoulder & it is very thin material & is diecast ****e.

Rang the suppliers, explained the situation & said I'd probably need to butcher the valve getting it out with a small cold chisel. No probs, we'll send you a new one gratis,. Just send the old one back.

As I had kept the original Lucas IAC I proceeded to remove it & it came out reasonably well.

However, in removing the ali plate that it screws into I found the 3 internal head screws loose-ish & they came undone quite easily. Removed the plate & found the gasket was stiff & hard. Ah ha! Was this the cause of my problems?

Cleaned everything up & replaced it all, but this time using some sealant on the gasket.

Now runs like a Singer Sewing Machine. A V8 one to be sure.

My point is this.

If you have this problem, it might pay to inspect the mounting flange at the back end of the engine for air leaks before looking elsewhere.

The next drive out will confirm this but now it looks very promising.

May have had 2 problems then.
1. A cruddy IAC which already may have been leaking. 2. A loose IAC mounting flange.

Meant to include in my initial post.

The torque for the IAC valve is only 18 Nm (13 ft/lbs) so it doesn't take a lot to overtighten it. I suspect this may have been part of the replacement failure & I may have overtightened it, however, there is not much meat between the motor body & the threaded section, probably 1.5mm & it's diecast. Probably a bit better than hand tight would do.

Then again, it may have been a weak faulty body from the outset.
Anyway she's a goin' back.