2k idle when warm

[28Zero]

My engine idles fine when started and for a short while after that, then after the engine warms up, it refuses to idle less than 2k. I think it's a bad EGR valve and so I'm going to replace that soon, but I heard from someone else that it could be a leak in the rubber tube from the filter to the AFM (which has a sensor, of course). This doesn't quite make sense to me, does it make sense to anyone else?

The rubber thingy is old and almost definitely leaks - I would think the only bad thing is that portion of the air is not filtered. Are there any other effects?

Cheers!

[Brett240]

if the leak lets air bypass the throttle body then yes it will increase the idle speed.

[drunkenmaster]

thermostat could be stuck in eternal warm up?

[28Zero]

I bought a new EGR valve and took off the old one. :eek: Holy-moley! There was at least an inch of gunk in the return port and I'm still cleaning out the gunk from the intake port. Obviously this part of the engine has never been looked after by the PO. Once I get that cleaned out I'll see if it helps out on the idle problem.

However, it seems that in order to really clean out the ports I need to take the manifold off, and I'm not ready to do that just yet. When I do, is there anything I should really watch out for? What's not adequately covered in the manuals? While it's off, what should I do also?

Cheers!

[sblake01]

Did you check your EGR valve before replacing it. Pull vacuum through the valve and see if it holds the diaphraghm up. If it does then it's still good. Use a piece of a metal coat hanger to force the carbon through the egr port. But as far as the idle thing, check between the folds in the throttle body boot for cracks. If you find cracks then you need to replace the boot. That idle problem can also be cause by a improperly adjusted BCCD. If your car is a California car, it has an altitude sensor which can also cause this problem. The FSM covers the adjustment of the BCCD and the altitude sensor if your car has one. Look into those things first before you remove the manifold. I doubt if the egr valve would cause the idle to remain high when the car is warm. People have removed them and blocked the opening in the manifold with no effect on the idle speed. I am not suggesting you do that but a plugged up egr port is really no different than a blocked off one.

[28Zero]

It turns out that the high idle was because of a stuck boost control valve. The inside gets a little rusty and presto, stuck valve. Mechanic found it easy enough. (I haven't done any research to find out where this boost control valve is, anyone know?).

Cheers,

James

[mholmes]

What did the mechanic do to fix this? I have the same problem with my '77 280.....any help is appreciated thx

[280~Master]

You say the mech found a stuck boost control? You never stated that you had a turbo in your car. This has confuzed me? Do you have turbo or not?Glad to see the mech fixed the problem though.