Please could you help me with the following problem

I've got a 1994 Volvo 440 1.8si With the Single Point Fuel Injection
B18U (I think it's the Renault Engine one). Covered 45k

The car is used for mainly long motorway trips and returns on average
40mpg.

The Air Filter and Plugs were changed 10k miles ago and an oil change
1k ago.

PROBLEM

On starting the car from cold the car idles at 1400 ish (I presume this
is the choke)

After a few minutes the choke would normally turn off and the car would
idle at about 950 ish.

Recently the car has started to idle erracticly i.e. some 30 seconds
after the car has been started from cold. The idle goes from 1100 to
1500 to 1100 to 1500 to 1100 to 1500 (this is all the time and when not
moving the car is constantly blipping the throttle so to speak about 60
times a minute) and keeps doing this until I turn the car off.
Sometimes it peaks up to 2000 !.

If I try and blip the throttle myself to get the car to calm down the
rev's sometime stick at 2000.

The only recent thing I've done is to add some fuel injection cleaner
to the car fuel and change the oil.

I've no Idea where to start please help !! I had thought an idle valve but I don't think the B18U engine has one ?

Unfortunately this is one of the 'known' issues with the B18U.

The idle is controlled by a stepper motor that opens/closes the actual throttle valve (it doesn't uses a separate 'bypass' air valve). Perhaps your throttle position sensor is going bad, so the ECU has trouble determining the throttle position. Check the connections with a multimeter to see if the resistor values change smoothly or 'jump'..

But... The main issue with the single point injection system is that the injector is in front (above actually) the throttle butterfly. At very small throttle openings (idling and such) the fuel can condense on the butterfly and the engine gets a very erratic fuel mixture.

You can try removing the air pipe to the throttle body and see if there's any dirt on/around the throttle butterfly and clean it.

Bye, Arno.

Have the same problem,(B18E engine) Mine is down to the idle control valve/motor not working correctly.
It is clamped on the front of the block beside the distributor.

Pull the intake hose off the throttle body and look inside. It;s probably gunked up. Wipe it out, being sure to move the butterly valve and wipe as far in as you can (use carb cleaner). Sometimes that stuff can be on there really good. You might have to take the TB off to get to it all.

If that doen's help or doesn't look messy, you might try cleaning the Idle Air motor. Not sure where it is and the 40's but someone probably does. If they are clogged they can cause the erratic idle you are talking about. I notice you don't think it has one, which it may not, but I would be surprised.

There is always the chance that it is Vacuum hoses as well. Check all of them and make sure that they are in good shape. Introduction of unmetered air is always a problem.

hope that helps


Sam