Volvo Owners Club Forum - View Single Post - Engine 850: B5252S/2.4/10v:

capt jack · Apr 18th, 2012, 20:52

Not a MAF but it will have a MAP sensor, tucked just above the radiator with a couple of electrical connection and a vacuum pipe. There'll also be an air inlet temp sensor in the inlet air trunking between the air filter box and the throttle body.

The ECU has to work out how much air is coming into the engine. On a car with a MAF sesnor system, it does this by measuring air flow MAF = mass air flow. On a car with a MAP sensor it does this by measuring the the Manifold Absolute Pressure and then using information about the air temperature to calculate the mass of air. This in turn is used to work out how much petrol to squirt through for the calculated amount of air. Sounds complicated but it's actually quite straightforward and generally reliable. If something's amiss however, you'll get problems of either under- or over-fuelling and the engine will misbehave.

Faults should throw a code and light up the engine management light.

I reckon a Haynes book would be a good investment to help you find your way around the engine bay.

Cheers

Jack

One last thing - make sure the throttle cable can move freely. They do rust up once the plastic sleeving starts to deteriorate. An easy fix to replace - but if it is a bit grotty try running some oil down the cable first!

Jack

Apr 18th, 2012, 20:52	#8
capt jack VOC Member Last Online: Apr 20th, 2024 18:56 Join Date: Jun 2006 Location: Selby, North Yorkshire	Not a MAF but it will have a MAP sensor, tucked just above the radiator with a couple of electrical connection and a vacuum pipe. There'll also be an air inlet temp sensor in the inlet air trunking between the air filter box and the throttle body. The ECU has to work out how much air is coming into the engine. On a car with a MAF sesnor system, it does this by measuring air flow MAF = mass air flow. On a car with a MAP sensor it does this by measuring the the Manifold Absolute Pressure and then using information about the air temperature to calculate the mass of air. This in turn is used to work out how much petrol to squirt through for the calculated amount of air. Sounds complicated but it's actually quite straightforward and generally reliable. If something's amiss however, you'll get problems of either under- or over-fuelling and the engine will misbehave. Faults should throw a code and light up the engine management light. I reckon a Haynes book would be a good investment to help you find your way around the engine bay. Cheers Jack One last thing - make sure the throttle cable can move freely. They do rust up once the plastic sleeving starts to deteriorate. An easy fix to replace - but if it is a bit grotty try running some oil down the cable first! Jack Last edited by capt jack; Apr 18th, 2012 at 20:55.