Engine 850: B5204S/2.0/20v: Engine Idle problem

[supraruss]

I have read a lot of other posts about engine idle problems. I have been getting failed MAF Sensor code on the diagnostic. The engine idles erraticly when in Park when engine is hot or cold.

I have cleaned out all of the air inlet pipes, throttle butterfly, idle air control, and lastly I will try looking for a leak in the vacuum lines.

Has anyone got a picture of the B5204S 2.0 20v engine so I can see where all the hoses are to check and make sure I look at all of them to eliminate this as a cause of the problem.

After this I may try replacing the ECT sensor and then MAF sensor if I have to.

[Volvo Dave]

Hi dont know if these will be of any use. They were taken a couple of years back when I removed the engine from our old 855 to replace the clutch.

[supraruss]

Thats excellent! Thanks for taking the time to post that for me. Its so much easier working from proper colour photos than a Haynes manual.

Thanks again

Russ

[Jod T5]

I would have a look at the flame trap which is a PIA on the NA models....
http://www.volvospeed.co.uk/Repair/ftrap.php
cheers
jod

[supraruss]

Checked flame trap and cleaned it all out - wasn't too bad. Put it all back and still the same! Checked hoses and can't see any leaks.

Noticed (sorry not sure what its called) a black plastic pole shaped thing ontop of the throttle body with lots of tiny pipes leading off of it to various places. Most of the front pipes on this are blocked with caps and the one with a hose I followed down leading to a white and black circle shaped thing?
What is this? Took it off and can't see how air can get through it whats it for? Could this be the problem? It then connects to a T hose and one hose goes off to looks like a sensor attached to the air box.

I'm gona give up soon and just start replacing sensors and maybe rotor arm dizzy cap maybe that will do it?

[Jod T5]

Originally Posted by supraruss

Noticed (sorry not sure what its called) a black plastic pole shaped thing ontop of the throttle body with lots of tiny pipes leading off of it to various places. Most of the front pipes on this are blocked with caps and the one with a hose I followed down leading to a white and black circle shaped thing?
What is this? Took it off and can't see how air can get through it whats it for? Could this be the problem? It then connects to a T hose and one hose goes off to looks like a sensor attached to the air box.

that will be the vacuum tree, could well be to do with the opening mechanism used during cold start, it would only be an issue if the pipe was split...
i would SERIOUSLY suggest you start with the basics and make sure you have carried out a stage 0 tune up before you throw your money into replacing sensors, search for stuart-volvos thread where he replaced almost every part on his t5, when the problem lay with a basic lack of spark due to a faulty immobiliser...
cheers
jod

[supraruss]

Thanks for the sound advice. I think thats the best thing to do. I've looked at the tune up. This is the best thing to do. After all, servicing is needed anyway so its not going to be wasted. Then after the servicing, if its still playing up, I will go further then.

Just one more question. I have checked for hose leaks but cant see any, although, while engine is running - I put my ear close to the throttle body area and I can hear air sucking noise - is this normal to actually hear the air from here? Or is this an air leak that I haven't discovered?

Seems to be coming from around the throttle butterfly area and tubes around the idle air control valve.

[Jod T5]

Originally Posted by supraruss

Thanks for the sound advice. I think thats the best thing to do. I've looked at the tune up. This is the best thing to do. After all, servicing is needed anyway so its not going to be wasted. Then after the servicing, if its still playing up, I will go further then.

Just one more question. I have checked for hose leaks but cant see any, although, while engine is running - I put my ear close to the throttle body area and I can hear air sucking noise - is this normal to actually hear the air from here? Or is this an air leak that I haven't discovered?

Seems to be coming from around the throttle butterfly area and tubes around the idle air control valve.

i could well be the IACV motor working, this is normal...
cheers
jod