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A8 Parts Forum (https://forum.a8parts.co.uk/index.php)
-   D3 - Common Faults (https://forum.a8parts.co.uk/forumdisplay.php?f=67)
-   -   running too lean (https://forum.a8parts.co.uk/showthread.php?t=3213)

Just_Ben 22nd July 2011 09:32 AM
Fault codes are merely a tool to point you in the right direction for further diagnosis, rarely can you trust a plain fault to give a 100% diagnosis. Using live data for fuelling, air mass etc should give an indication as to the issue.

reiss 22nd July 2011 05:44 PM
Quote:
Originally Posted by Just_Ben (Post 25216)
No, the fault code designation is funny so it sometimes only logs one bank, just to confuse ya!
just had vagcom on it again now its showing bank 1 and bank 2 cleared the fault and rechecked it and its showing both bank ! any suggestions ive put bg44k fuel system cleaner as a precaution

reiss 22nd July 2011 05:49 PM
Quote:
Originally Posted by Just_Ben (Post 25217)
Fault codes are merely a tool to point you in the right direction for further diagnosis, rarely can you trust a plain fault to give a 100% diagnosis. Using live data for fuelling, air mass etc should give an indication as to the issue.
as its showing bank 1 & 2 do you think the problem could be a clogged fuel filter or a weak fuel pump?

does anyone know of a good mechanic who works on audi a8s around the blackburn area?

ainarssems 22nd July 2011 09:26 PM
If after clearing faults it comes back while on idle, then it is most likely to be vacuum leak followed by O2 sensor or Maf fault.

If it reoccurs only after part/full throttle then it could be fuel filter or fuel pressure regulator.

Most of the times fuel pump just seize up and stop working but it is possible that it is worn and cannot keep up pressure.

reiss 23rd July 2011 01:13 PM
Quote:
Originally Posted by ainarssems (Post 25250)
If after clearing faults it comes back while on idle, then it is most likely to be vacuum leak followed by O2 sensor or Maf fault.

If it reoccurs only after part/full throttle then it could be fuel filter or fuel pressure regulator.

Most of the times fuel pump just seize up and stop working but it is possible that it is worn and cannot keep up pressure.
it only re occurs after ive driven it about a 100miles after ive reset the fault i think ill start by changing fuel filter on it first

reiss 25th July 2011 09:41 PM
Quote:
Originally Posted by reiss (Post 25278)
it only re occurs after ive driven it about a 100miles after ive reset the fault i think ill start by changing fuel filter on it first
right changed fuel filter and its still showing the fault after reset! its now also showing cylinder 5 injector circuit malfunction! ive just remembered that i had the car recently mapped could that be causing the problem as i asked for the map to be more economical.:o

A8 Doc 28th July 2011 09:19 AM
Who mapped it mate? Has it just occured after this?

Cylinder 5 injector sticking could be your issue. If you can swap the injector around and see the fault follow.

ainarssems 28th July 2011 04:50 PM
Quote:
Originally Posted by reiss (Post 25376)
right changed fuel filter and its still showing the fault after reset! its now also showing cylinder 5 injector circuit malfunction! ive just remembered that i had the car recently mapped could that be causing the problem as i asked for the map to be more economical.:o
That means resistance for injector 5 circuit is out of specified range- either short circuit or open circuit. Check wiring and plugs for injector 5 for damage, corrosion and loose connections. Swap injector 5 with another one and see if the fault follows it.

Quote:
Cylinder 5 injector sticking could be your issue. If you can swap the injector around and see the fault follow.
Sticking/clogged injector could result in lean readings and/or misfire but would not throw electrical circuit malfunction code. More likely to be loose connection either in the wiring or inside injector itself or damaged wiring.

I suppose mapping could result in running lean but I would concentrate on getting injector 5 sorted out first.

reiss 28th July 2011 04:55 PM
Quote:
Originally Posted by A8 Doc (Post 25509)
Who mapped it mate? Has it just occured after this?

Cylinder 5 injector sticking could be your issue. If you can swap the injector around and see the fault follow.
WP auto solutions remapped it via elite tuning house, it did happen once before but since ive had it mapped the light comes on everytime ive reset it ive changed the injector just to be on safe side but that fault is still showing up!:Confused:

reiss 28th July 2011 04:57 PM
Quote:
Originally Posted by ainarssems (Post 25526)
That means resistance for injector 5 circuit is out of specified range- either short circuit or open circuit. Check wiring and plugs for injector 5 for damage, corrosion and loose connections. Swap injector 5 with another one and see if the fault follows it.



Sticking/clogged injector could result in lean readings and/or misfire but would not throw electrical circuit malfunction code. More likely to be loose connection either in the wiring or inside injector itself or damaged wiring.

I suppose mapping could result in running lean but I would concentrate on getting injector 5 sorted out first.
got injector 5 sorted it turned out to be a loose connection but after reset its still showing the fault


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