Re: [DML] more idle speed issues

[Martin Gutkowski <webmaster@xxxx>]

Hi James

I don't have a specific answer to your problem but I can answer several 
of your questions. That said, check your idle speed microswitch - it's 
activated by the throttle lever on top of the engine.

James La Londe wrote:

> Normally it idles at around 1500 rpm, which is not too loud or too off the wall for me to have fixxed it... yet.
... unless you own an automatic!

> The car is timed correctly, and the belts are new. But it needs new ignition wires and spark plgus, probably a distributer, and it's coming up on an oil change. 
If it runs smoothly then the plugs/dizzy/leads are doing their job. 
Still worth checking and replacing as a matter of course (esp if 
original) but I think the problem's elsewhere.

> I've heard about the O2 sensor too... I'm not sure of it's function or how it could come into play here... can someone brief me on it... a little 101 if you will.
The Lambda system works by measuring the oxygen present in the exhaust. 
If there's too much, the engine's running lean, if there's too little, 
it's running rich. The lambda computer adjusts the mixture "on-the-fly" 
by altering the duty cycle of the frequency valve. This is mounted to 
the top of the right bank, easily accessible by removing the air box, 
and when the engine's running, it should be buzzing like an angry 
cricket. If the lambda sensor is duff, or if you unplug it, the lambda 
computer sets itself to a constant "slightly rich" mixture. It will 
contribute to, though not cause, an idling problem

> Other possibly related things. the car lacks an ignition coil cover, and on start up every morning it severly bogs down until you've gone about 1/2 mile and then it runs okay (but still at 1500 rpm idling).
When the engine is cold, the fuelling is controlled by the control 
pressure regulator - the grey box on the engine on the top of the left 
bank - it has two fuel hoses going to it, plus an electric connector and 
a vacuum lead. When the engine reached a certain temperature, the lambda 
system comes into play and it is at this point that you can feel a 
sudden change in behaviour (my car used to get a lot worse suddenly). On 
what you've said, it sounds like your CPR might need attention. John 
Hervey can sell you a rebuilt unit.

> When the car is around 1/16 a tank of gas it starts to gulp air and thus bog severly... but i've been told it's because it lacks a baffle at the bottom of the fuel tank. 
I'm amazed you can get that low before you have problems if you're 
lacking the baffle base.

Martin
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