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robert · Posted: Wed Jul 21, 2004 11:22 pm Post subject: idle speed on 33 16V

Hi,

The idle speed on my 33 16V is sometimes 2000rpm. This is an intermittent problem that has been gradually getting more common and there doesn't seem to be a relationship with how warm the car is. Normally the idle speed is correct (900rpm) with the error occurring about 1 time in 3.

I have recently had the car serviced (new oil, filter, plugs, and leads). There are no fault codes and I have cleaned the crankcase breather.

Any ideas.

Robert

lesthegringo · Alfasud Joined: 23 Jul 2003 Posts: 97

Check the idle speed control valve ( the silver cylinder attached to the front of the four legged intake casting).

It is connected via a plug similar to an injector plug, so clean the contacts. If this doesn't work, see if you can borrow one to test.

Les

tvatavuk · Posted: Fri Jul 23, 2004 2:15 pm Post subject:

Hello Robert,

there are also few other things you can check,

- usualy it is thermostat (which is inside welded housing) that makes your car act like that, when it is stuck or when it never fully closes. It isn't too much complicated to remove it if coolant isn't hot.
- sometimes cloged or cracked pipes to idle valve
- cracked rubber on air intake
- bad temperatre sensor
_________________
Tino Vatavuk
Little black dress which replaced Alfa Romeo 33 S 16v Permanent 4 GMo

Deano · Posted: Fri Aug 13, 2004 11:27 am Post subject: Re: idle speed on 33 16V

If you remove the air plenum on top of the engine then underneath you will find a metal bar approx 30cm long which is connected to the throttle cable and controls the opening of the 4 butterfly valves. This metal bar is supported at each end by a bearing and it is common for these bearings to rust with time and become sticky to the point where the return spring is no longer able to shut the butterflies on idle. You should be able to free the bearings up with some WD40.

amir · Posted: Fri Aug 13, 2004 3:38 pm Post subject:

The injection has a self diagnosis. When the diagnosis thinks something went wrong, it switches the ECU to the "limp-home-mode". One of the side effects is the altered idle speed. Maybe thats your problem.

The only way to find out is to install a device that shows the errors. It can be done DIY. I can send a guide how to make it, its very easy and cheap.
_________________
33 P4
75 Milano
155 TD 2.5

robert · Posted: Sun Aug 15, 2004 5:10 am Post subject:

Hi all,

Many thanks for the help. I sprayed some contact cleaner on the connection to idle speed control valve and the idle speed has been normal now for a couple of weeks.

Cheers, Robert