Quote:
Originally Posted by 2001sport  Actually, I believe there have been a number of people on this forum, including myself, that have solved lean bank 1 (code P0171) CELs by replacing the MAF. I've also read that the fuel filter could be a potential cause... |
As with any fault, you do not simply replace components without a formed diagnosis....
MAF is unlikely due to:
a) Lambda control will correct air measurement problems once the vehicle is warmed up and hence the ECU will report a general low/high MAF reading...
fault code
b) The MAF measures air to both banks....so why would only one report lean.
I am still yet to see an in service MAF failure in all my years of working on these....I have seen many MAF fault codes but never a real failure.
The trouble is the MAF is a very miss understood beast and most techs these days are simple creatures....if a MAF failure is suspected then further work needs to be done to confirm it i.e.:
1) Scantool operation of the EGR whilst monitoring MAF readings
2) Vac gauge tests to check for un-metered air getting in...
The question I asked above was slightly loaded as in relaity there is only one real thing that can cause a lean bank which the ECU can not correct and that is a lack of fuel.
The valley question was based on past experience where people in a rush have faield to spot the multiplug connector for the injector/inlet assembly and removed the connections from the injectors, these are difficult to get back on unless you know how and hence there might be an intermittent injector.
Again, this could also be a blocked fuel filter (surely these are changed are the correct service intervals
), this is normaly pretty obvious when revving as the car struggles at higher revs almost as if a limiter is kicking in....and would normaly affect both banks....
Hence, more info needed before diving in with willy nilly part replacement which only adds more confusion to the diag i.e.
'Was the replacement part faulty, or not, or was it not that part at all....'
