MAF help! (p1171 code)

[itguy]

Hi Everyone

Need some opinions here please.

I've been getting a p1171 code set in my ecu for months now and sometimes it gets bad enough to bring the MIL/CEL light on the dash.

So time to investigate I thought. Readings are;

Long term fuel trim, 22% - short term upto 20% in addition when driving.

Idle mass throughput is 3.00 to 3.25 g/s at idle (660 rpm) with aircon off.

Now, from what I've read elsewhere it seems like the idle throughput is a bit low and that the MAF is just under-reading a bit. So, I bought a replacement from a company near Ikea, J26 of the M1. Brand-new bosch *copy* item, not genuine.

Fitted it, did an ECU reset (overnight with the battery off and via the OBD2 s/w) and it now idles poorly, fluctuating a bit, bogs when you first touch the throttle and it has also stalled a few times when pulling up to lights (my car is a geartronic btw). It does have a long term fuel trim of only -1.4% (after 100 miles).

Not good - car runs worse than before I changed it.

So I've now put back the first one (that one is a bosch) and it runs as it did before, 22% long term trim but idles and revs cleanly with no bogging.

What's the next step then?

1) Ideally I'd love to borrow a MAF from someone who knows it works fine and test it in my car (phase2, 2000 model year T5),

2) Return the new MAF for a refund and buy a genuine bosch one at twice the cost from partsforvolvosonline.co.uk

3) Return the new MAF and buy a used one from Salvo for about the same cost

4) Keep the new MAF, put it back in and hope the ECU learns to cope with the new way that it works (adaptations maybe?)

Is there something else I've missed totally? Lambda/EVAP etc?

Any help gratefully received.

Thanks

[HSS786]

Hello there I was registered as SID786 I recognise your name, before the forum crashed, I had a very similiar problem as yours, my car would idle rough and would die when i pressed the throttle, I changed the MAF but the symptoms were the same, I had my CEL light on along with the message "Engine Systems Service Urgent", in the end it turned out to be a ETM fault which resulted in a new ETM from Volvo dealer, try unplugging the MAF and see if the Idle improves, if it does then the MAF is to blame.

Hope this helps thanks

[itguy]

Interesting - thanks for the advice, will try.

Have never had a message in the DIM relating to anything about the engine - no messages about 'reduced performance' or 'systems service' etc though.

[Wombatbomb]

The copy MAF's are awful, I had mine replaced under a warranty just after I bought my car, with the supposedly correct unit. Ran like a bag of spanners. On inspection, that's not a real one, that's a copy. Remove crappy pattern part, insert shiny new genuine Bosch, no worries! There's a guy on fleabay who sells genuine Bosch units for £70, and all the reports I've seen say they are the proper ones and work fine.

[itguy]

yup, that's the conclusion I am coming to.. I can't find the genuine bosch ones on ebay though at the moment

[Wombatbomb]

Try item numbers 150266608616 & 160255728182. I think that is the correct seller, and he states they are genuine Bosch units. (I don't know what car you have though!)

[itguy]

Thats the one that I bought and went to collect!

It's defo a copy and not genuine

[CONDYBOY]

If you have a "LUCAS" dealer near you try them they are usually pretty good at sourcong bosch parts.

[itguy]

Interesting - thanks for the tip

[itguy]

Well very chuffed after tonights efforts.

Cornclose from this forum assisted me with my investigation by lending me his MAF (known to be working well with only 2.3% long term trim) for me to try in my car.

Popped it in and viola! 2.3% trim shown on my car too!!! So, everything else works just fine, high speed 'off throttle' hesitation was gone, car ran really well.

Spoke to the company who supplied the copy MAF today and they agreed it sounded faulty, will happily take it back and refund.

Have now ordered a genuine one from pfvonline (sorry Rufe, just a bit too much this time!), so in a few days time it will all be finished/sorted.

Thanks cornclose

Will

[cornclose]

No Problem Will - any time.

[t5owner]

Hi Everyone

Need some opinions here please.

I've been getting a p1171 code set in my ecu for months now and sometimes it gets bad enough to bring the MIL/CEL light on the dash.

So time to investigate I thought. Readings are;

Long term fuel trim, 22% - short term upto 20% in addition when driving.

Idle mass throughput is 3.00 to 3.25 g/s at idle (660 rpm) with aircon off.

Now, from what I've read elsewhere it seems like the idle throughput is a bit low and that the MAF is just under-reading a bit. So, I bought a replacement from a company near Ikea, J26 of the M1. Brand-new bosch *copy* item, not genuine.

Fitted it, did an ECU reset (overnight with the battery off and via the OBD2 s/w) and it now idles poorly, fluctuating a bit, bogs when you first touch the throttle and it has also stalled a few times when pulling up to lights (my car is a geartronic btw). It does have a long term fuel trim of only -1.4% (after 100 miles).

Not good - car runs worse than before I changed it.

Sound`s like you got your new MAF from the same place as i got mine and i had exactly the same probs as you`ve described and mines a manual

I`ve sent the MAF back for testing and i think i`ll get a refund then bite the bullet and get the genuine item from volvo

Cheers

stuart

[itguy]

Right - thought I'd finish this thread off with the outcome.

Bought a new genuine bosch MAF from partsforvolvosonline and fitted it two days ago.

Have done about 100 miles on the new MAF and the car is WAY better. No fault codes, long term fuel trim now at 0.8%.

MPG has gone from 19-20 to 23.9 (currently) so am well happy.

Car doesn't jerk now either when lifting off from full throttle at 4krpm+ like it did before.

All in all, job well done

[cornclose]

Says volumes about using genuine parts doesn't it ?