Hi, I have a '99 1.8liter petrol S40.

Lately it has seemed the engine is giving a little less power than I was used to, but I thought it's just because I was driving around with a car full of people and luggage. Few days later, however, the car stopped starting.

I was able to fire it up by putting starting spray into the intake and keep it running with a foot on the accelerator, but as soon as I let the rpm go below ~1300 the engine stalled. Above ~1500rpm the engine runs nice and smooth.

I tried plugging it to a OBD unit, but it was a rather cheap Chinese one, so it did not tell me much.

From what the engine does it clearly seems it is not getting the right mixture at low rpm, but there's a ton of reasons why this could be happening.

Can someone suggest what might be the most probable cause of this behaviour or tell me what to try to find it out without investing in a proper diagnostic unit?

 

air leak
O2 sensor
Fuel pressure

 

The s40 in that year range has an electric idle control valve that goes bad and fails to control the idle speed. Have replaced several over the years
Wide variety of prices out there - here's one from amazon, and cheap aftermarket ones are out there too -