New member- Idle adjustment on 740 GLE est b230e 8v late 89

[alsner]

Greetings. I've recently aquired a very tidy estate with FSH (every stamp and bill from new) 127k on the clock. Generally very happy but a couple of little niggles are getting me down.

Can anyone give me advice on how to alter my idle speed? currently low around 550 - 600rpm when warmed up, should be 900 rpm. My car is a late 89 (newer styling). I'm not very mechanically minded but can find my way around with good directions. I'm not sure what fuel injection system I have fitted so the advice on the FAQ leaves me confused, I think its CI fuel injection (what does this mean in real terms?). It appears some are adjustable and some are not without major time investment.

Has anyone come across intermittent heater fan/ electric mirrors/ cigarette lighter? Have checked the fuses and all seem intact. I believe it is fuse related because if it fails and I remove the fuse and replace with the same fuse all is well. Sorry for the essay but any help greatly appreaciated.

[TheJoyOfSix]

Re the idle adjustment;

Standing at the front of the car look at the top of the inlet manifold. If you have a B230E this should be rectangular with 4 long pipes down to the head and the air inlet/throttle body should be underneath the rectangle.
At the lower front right corner of the rectangle there should be an ally tube with a black plastic screw/knob protruding at 45* to the rectangle and pointing slightly downwards. Turn this knob clockwise to slow the idle speed, and thus anti-clockwise to speed it up.

However, many causes of low idle on these engines are just 'gunk' in the intake system. I'd advise disconnecting the air intake from the airbox and whilst holding the revs at 3000rpm on the throttle spray a can of carb cleaner into the intake. I'd also disconnect the air idle valve (ally device bolted vertically with two allen bolts to the cam cover, and has a hose connected top and bottom) and spray some carb cleaner through that too.

The intakes gum up over time as the crankcase ventilation system vents to it. This restricts the volume of air to the engine with the result that the idle slows down. Many unscrupulous garages when servicing a car will simply give the car more air via the idle screw thus creating the impression that all is well.

I performed this treatment to a friends 740SE (B200E) and the idle speed rose from 700rpm before cleaning to 1700rpm after cleaning!

[alsner]

Thank you for your rapid response to my question. All the info needed and very easy to understand.

Have you any ideas on electrical issues? I though I might just change all the major fuses for brand new ones but the logical part of my brain says that wouldn't make much difference because an electrical connection is just that. unless I have a bad earth somewhere!!