Engine: S60: emmisions light

[reggit]

Car is a 2002 with 85,000 miles 2.4 non-turbo petrol S60, and new to me so unfortunately I've a limited knowledge of it's history.

It has thrown an emmissions light up - I've read the error which comes up as ECM250A - Long-term fuel trim, upper limit. I've reset it but it pops back after a short while, although this could be up to 10's of miles

This points toward the MAF sensor, Vida also suggests a possible airleak - the sensor looks new, and the oringinal one is in the boot suggesting this has recently been a problem for the previous owner.

I've noticed as well that the engine hunts very slightly at tickover, don't know if this is related.

Assuming I'm looking for an airleak, any suggestions on where I should be looking? I assume inlet side?

I'm ignoring the low fuel pressure possibility as the car is a factory bi-fuel and the warning is present running on either fuel.

[Missing Lincs]

Volvo told me that it could also be a Lambda sensor problem, I'm not sure about that idea as when these go faulty they generate codes of their own.
I had the same code with mine, turned out to be the MAF sensor. Are you 100% sure you have a new MAF fitted? Mine was still working but not within spec and it looked like new when removed. On some models of MAF it is possible to change the sensor element rather than the whole assembly. Even if you buy the whole thing its easier to swap just the sensor.
If the MAF has been changed and you suspect an air leak, check where the pipe fits onto the MAF body.
Hunting at low revs also sounds a familiar symtom of a ETM (throttle) problem. Not sure this would cause the fuel trim problem though?

[Georgeandkira]

Hello, In addition to what you've learned so far, look at this post.

http://www.volvoforums.org.uk/showthread.php?t=144619

Any of the hoses connected to the manifold in those pictures can be cracked as well. Good luck. Kira

[reggit]

Hi Kira,

Thanks for the link - unfortunately my car doesn't bear much resemblance, most likely due to the bifuel variant.

I've checked over all the hoses I can see and all appear sound, one of them goes to a sensor on the radiator, then clears off under the engine - I can see it running along the subframe, then it goes out of site, no idea what that one does. I'll put a couple of pics up for comparision.


Back of airbox - you can see where it would be drilled for the pipes, but mine hasn't been


Inlet manifold - the 'elbowed' pipe runs to the LPG vaporiser.


Other end of the 'elbowed pipe' entering the vaporiser.

I noted that the replacement MAF sensor is a pattern part, so I've ordered a new 'used but guaranteed' item from a breaker so I'll have to see what happens when that gets put on.

[reggit]

Woo-hoo, put a 'new' MAF sensor on and no more emmissions light. OK, I reset it but it hasn't popped back on yet....

also the car is currently running properly on LPG, it kept cutting out. I wonder if related or just coincidence - it'll probably play up again tomorrow now I've said it's running well.

Just the airbag warning light to deal with now!

[reggit]

Grrr, the light just came back on

One of the causes is low fuel pressure - if this was the cause, would the light go out again on its own if the pressure returned to normal?

I think the LPG may have run out as I had to turn it to petrol because it felt to be running out of fuel - either that or the blooming LPG has faulted again. I would have expected the light to extinuish as it turned back to petrol if the LPG system pressure was low due to exhausted tank.

[outnumbered]

fuel filter

[Thanatos]

i have vida and dice in blackpool if you want a trip over to get rid of the srs light and see what vida says to check. for the light might be a faulty lambda sensor

[reggit]

Ta for the offer, got vida/dice myself as well - multiple airbag issues and wiring issues to the passenger seat, all high resistance. Suspect a duff connection somewhere. Comes back instantly when I clear codes (assuming I'm doing it right).

Still learning with Vida, assume I should be able to read the live values somewhere? Been wanting to see what the Lambda is doing although it hasn't thrown any codes.

[outnumbered]

if you click on veh comms then on ecm then activate scroll down to what you want to monitor and click to add to list you can have it graph or table.
mike