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Post by thecurleyone on Jun 2, 2015 17:23:40 GMT 1
Hi all.
Been a while since I've posted on here, still visit regularly though!
Have a Volvo V70(X reg. 2.4 20 valve petrol) in at the moment, MIL on.
Fault code is 250A Long term fuel trim malfunction.
Have checked for air leaks, found breather on front of block was leaking so have replaced that and all the associated hoses etc.
Reset fault codes and ECU.
All was OK for a while but light is back on with same 250A code.
In live data scan tool shows long term fuel trim area 1, 2, 3, 4, 5.
Areas 1 and 2 are showing high (1.22 and 1.17) whereas 3,4,5 are all on 1.04.
What I would like to know is, what are the five separate areas referring to? Individual cylinders was my guess but not convinced.
Any help appreciated.
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Post by valhalla on Jun 3, 2015 23:46:20 GMT 1
I believe that this Volvo still uses the regional fuel-trim terms, i.e. each spead/load region has a separate trim area. So once the engine is warmed-up and closed-loop, there will be one trim around idle, and several others around various speed/load boxes. I would have to consult my notes to confirm what the domains are in this particular case, unless you can use an OBD toolset to do this for you?
The probability is that region 1 is around idle, and region 2 just above idle. If that was the case, then you have an idle-enrichment issue, pointing to an inlet manifold leak or similar.
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Post by thecurleyone on Jun 4, 2015 10:47:49 GMT 1
I believe that this Volvo still uses the regional fuel-trim terms, i.e. each spead/load region has a separate trim area. So once the engine is warmed-up and closed-loop, there will be one trim around idle, and several others around various speed/load boxes. I would have to consult my notes to confirm what the domains are in this particular case, unless you can use an OBD toolset to do this for you? The probability is that region 1 is around idle, and region 2 just above idle. If that was the case, then you have an idle-enrichment issue, pointing to an inlet manifold leak or similar. Thanks for your reply. Found that on scanner it actually shows the area being monitored whilst driving. And as you correctly say area 1 appears to be idle and then up to five at full throttle. This will help a lot. Thanks |
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Post by thecurleyone on Jun 9, 2015 11:23:00 GMT 1
Just a quick update.
Start with the basics as they say!!
No air leaks found, did have but fixed that a while ago with new breather system, but good to check again.
So dirty air filter replaced and the dirtiest MAF I have ever seen given a good clean with intake cleaner.
All appears good at the moment.
Will update when it has had chance to do some more miles.
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Post by thecurleyone on Jul 5, 2015 11:26:09 GMT 1
Oh well, the light is back on, same fault code, 250A long term fuel trim malfunction.
Live data shows area 1 as 1.22, area 2 as 1.15, areas 3,4&5 are all 1.01.
So the fault occurs in the idle and just off idle areas.
Not quite understanding what causes the trims to be out in the low speed/load areas and OK higher up.
Things done so far.
Checked for air leaks with smoke machine, leaks found around breather houses/canister on front of block. All striped down and new hoses/canister fitted. Rechecked for air leaks, all good. Codes cleared and ECU reset to clear fuel trim data back to zero.
New air filter and a previously filthy MAF now sparkling.
Does anyone have an idea where to start investigating?
Thank you.
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gasmonkey
Tea Maker
At an Oscilloscope near you.
Posts: 444
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Post by gasmonkey on Jul 5, 2015 19:15:43 GMT 1
Injector/s leaking?
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Post by Dragon on Jul 5, 2015 23:48:59 GMT 1
Try a new genuine MAF??
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Post by thecurleyone on Jul 6, 2015 8:01:02 GMT 1
Funnily enough the above two suggestions (thanks ) are the very two I suggested as possible causes  Vehicle done nearly 200,000 miles and both parts are original as far as I can tell. May well be worth sending injectors off to be tested/serviced any way in view of age/mileage. Will have a look later and see. Thanks. |
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Post by Noberator on Jul 6, 2015 16:00:54 GMT 1
Is the drive lumpy and has the MPG dropped since the problem arose?  |
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Deleted
Deleted Member
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Post by Deleted on Jul 6, 2015 17:04:56 GMT 1
Oh well, the light is back on, same fault code, 250A long term fuel trim malfunction. Live data shows area 1 as 1.22, area 2 as 1.15, areas 3,4&5 are all 1.01. So the fault occurs in the idle and just off idle areas. Not quite understanding what causes the trims to be out in the low speed/load areas and OK higher up. Things done so far. Checked for air leaks with smoke machine, leaks found around breather houses/canister on front of block. All striped down and new hoses/canister fitted. Rechecked for air leaks, all good. Codes cleared and ECU reset to clear fuel trim data back to zero. New air filter and a previously filthy MAF now sparkling. Does anyone have an idea where to start investigating? Thank you. As Nobster says any drivability issues ? some testing results needed or its all speculation |
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Post by thecurleyone on Jul 6, 2015 20:21:52 GMT 1
Is the drive lumpy and has the MPG dropped since the problem arose? No lumpiness! No noticeable drop in economy, not exactly a frugal car at the best of times! Thanks |
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Post by Noberator on Jul 6, 2015 22:20:12 GMT 1
Is the drive lumpy and has the MPG dropped since the problem arose? No lumpiness! No noticeable drop in economy, not exactly a frugal car at the best of times! Thanks Do you know anyone who has VIDA to check the Parameter values for the Mass air flow, air flow voltage and the Oxygen sensor(s) and engine speed and higher(ie tickover and 1500 rpm 2000 rpm and say 2500 looking for a slight voltage increse.  If the voltages are ok it may show the MAF is showing too much air flow or not and rule it ok then it could be something to do with the STFT the LTFT |
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Post by valhalla on Jul 10, 2015 22:04:24 GMT 1
You say that the breather system has been jollied-up some time back, but it's worth re-checking that the PCV has been replaced of recent - very common to find these knackered on the 5-cyl Volvos, and not a bad idea to change the whole lot (PFS, etc. can do a package) as a routine service item.
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Post by thecurleyone on Jul 11, 2015 11:45:14 GMT 1
Yes, did the whole lot, all the hoses, big plastic housing etc.
Rubber glove over oil filler cap hole shows strong vacuum.
Haven't had chance to look at any further yet.
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