91 740 Auto Wagon Initial Idle Probs

[goldmember]

G'day

I have a 1991 740 Auto Wagon which when first starts up, blows just a small puff of smoke (from the exhaust), the revs wobble then is relatively OK. It doesn't seam to idle very smoothly but gets better as it warms up, but is never perfect.

Fuel consumption is hardly affected (if at all). Recently the head was redone due to overheating on a hot day (temp fitting broke and I didn't realise, but thats another story).
Before the head was redone it was just serviced and it ran beatifully.

The mechanic seams to think it is either the Air Mass Flow Meter or one (or more) injectors could be just dripping a tiny bit of fuel in. To find out means exploratory surgery that could take hours. He has already done heaps of hours on it gratis as he is a friend and don't want to burden him with it.

Has anyone any idea what could be causing this and where I should look? I have already carefully cleaned the air mass meter with electronics solvent without any affect at all.

The only code showing is: 2-3-2:
Which according to some software I have says:
Lamda Adjustment - Check Intake manifold; Check Fuel Pressure

I don't know how to do these things, but I realise it could be something else.

Cheers

George

[billofdurham]

Welcome to Matthew's Volvo Site.

As you have come up with the code 2-3-2, check inlet manifold/fuel pressure, the first thing I would check would be for a leak at the inlet manifold. They can close up as the engine warms thus removing some of the symptoms.

As you have had the head done the inlet manifold would have been off and may not have been replaced properly.

Bill

[waynej]

You can find the intake manifold leak with a spray can of Carb/Throttle body cleaner. Start eng cold and spray cleaner around all connections to manifold, especially where it mounts to head. When you hit the leak the idle will smooth out for a second or two.