Engine: S60: Long term fuel trim - upper limit

[reggit]

Next on the list of problems I have a check engine light on (again!).
Car is a 2002 S60 bi-fuel, 2.4 non-turbo


Vida shows the following error

ECM-250A Long-term fuel trim. Upper limit

(there's also one obout the LPG system, but that isn't an issue at the moment as I'm only using it on petrol until everything else is right)

And shows the following possibilities:
Upper limit:
Damaged mass air flow (MAF) sensor
Low fuel pressure
Air leakage.

The cars has had a new aftermarket MAF sensor, and a 'new' 2nd hand genuine sensor - all 3 show the same symptoms, so can probably rule that out.

I can't see any evidence of air leakage, have a good check of all the inlet tract, and sprayed with WD40 with no effect.

Don't know how to check the fuel pressure - could a blocked filter be the cause? I've not got this far and it's previous history is somewhat dubious to say the least.

Any advice welcome

[Missing Lincs]

In my case this error code was because the MAF was faulty. Replaced with a new genuine Bosch from a specialist supplier and has been OK since.

Another possible fault that was suggested to me was faulty O2 sensor. I thought that this would bring up an error code of its own, but apparently not, if the sensor is on its last legs, it may be working but giving erroneous readings In my case, I was pretty sure this wasn't the case as the front O2 sensor had just been changed, the heater went open circuit.

Best of luck with this one.

[Missing Lincs]

Just a thought, how does the dual fuel system change from petrol to LPG? Could there be a faulty valve causing reduced fuel pressure/flow?

[reggit]

Thanks for that, I may have to bite the bullet and replace the MAF with a new one

I don't think the LPG is related as it currently has a fault, I'm running the car solely on petrol until I get all it's other issues ironed out - the petrol injectors are turned off when the LPG turns on, so I assume the petrol rail maintains running pressure all the time.


Where did you source your MAF from?

Cheers

[Missing Lincs]

I did a Google search for the part number. Got mine from http://www.airmassmeterspecialists.co.uk/

[Clan]

Originally Posted by reggit

Next on the list of problems I have a check engine light on (again!).
Car is a 2002 S60 bi-fuel, 2.4 non-turbo


Vida shows the following error

ECM-250A Long-term fuel trim. Upper limit

(there's also one obout the LPG system, but that isn't an issue at the moment as I'm only using it on petrol until everything else is right)

And shows the following possibilities:
Upper limit:
Damaged mass air flow (MAF) sensor
Low fuel pressure
Air leakage.

The cars has had a new aftermarket MAF sensor, and a 'new' 2nd hand genuine sensor - all 3 show the same symptoms, so can probably rule that out.

I can't see any evidence of air leakage, have a good check of all the inlet tract, and sprayed with WD40 with no effect.

Don't know how to check the fuel pressure - could a blocked filter be the cause? I've not got this far and it's previous history is somewhat dubious to say the least.

Any advice welcome

If you have vida have you read out the airflow at idle ? see if it compares with the description ie figure expected ?
I have come across this circumstance with non genuine air mass meters on 10 year old cars, twice this year already and it was the air mass meter , a non volvo air mass meter is a bad move a high risk , fitting the correct part cured them . air mass meters have been about £250 since the 1990's but recently taken a hike in cost for some reason !

[reggit]

If I read it right - still learning my way around VIDA - the MAF is showing too much air flow, I may change it tomorrow with a spare unit I have just to check the figures. The one currently installed is a genuine unit.

Readings taken at operating temperature, ambient air temp around 18C

See pic below.


The figures quoted on Vida are:

[Clan]

Originally Posted by reggit

If I read it right - still learning my way around VIDA - the MAF is showing too much air flow, I may change it tomorrow with a spare unit I have just to check the figures. The one currently installed is a genuine unit.

Readings taken at operating temperature, ambient air temp around 18C

See pic below.


The figures quoted on Vida are:

well yes it is showing more airflow at a lower rpm than stated so the difference is even more than it first appears .. best compare a few different mass meters if you have them. Can you borrow a known good one?

[reggit]

Well - I could only find one of my spare MAF's, it was chucked in the car boot when I bought it. The car ran appallingly and the readings where even higher than the one installed.

I ended up finding a stockist of Denso made MAF's for about £100 and took the plunge in buying one. Just fitted it and the airflow readings through the rev range are as vida suggests they should be.

So much for my idea that 3 units couldn't exhibit the same fault!

Thanks for the pointers on vida - I'm still amazed at what it can do/tell you.

[gmovies]

Originally Posted by reggit

Well - I could only find one of my spare MAF's, it was chucked in the car boot when I bought it. The car ran appallingly and the readings where even higher than the one installed.

I ended up finding a stockist of Denso made MAF's for about £100 and took the plunge in buying one. Just fitted it and the airflow readings through the rev range are as vida suggests they should be.

So much for my idea that 3 units couldn't exhibit the same fault!

Thanks for the pointers on vida - I'm still amazed at what it can do/tell you.

I interpret this to mean the Denso MAF worked ok?

More importantly, here we are ten years later and I'm curious how long the Denso MAF lasted?

Thanks in advance.