Hello Matthew , using my mass air flow calculator im getting
640 rpm 6.7 g/s
2000 rpm 20.05 g/s
So we are loosing air.... or the reporting of air mass is off ( air mass meter ).... or air cannot get into engine (blocked exhaust route )
Does the car pull well if you put your foot down .....with blocked cats the more you boot it the more it will die a death from lack of flow
For it to affect idle readings the cats or exhaust would have to be pretty blocked which would kill mid and top end .
You say you have had a genuine air mass ......is this genuine audi part or a genuine bosch one from a motor factors or Euro car blaggers or somewhere ??
loads of Chinese copy supposedley gen. bosch air masses out there ........seen this a few times now ......under performing air masses affecting fueling ........seen over performing ones as well .......black smoke r us .
Try this i want to see if the lamdas are reading rich .............
clear all adaptations first .......go into short term fuel trims for both banks hold rpm at say 2000 if trims start going to plus values ( ecm adding fuel ) slowly clamp off fuel return line from injector rail .........making it artificially rich ........do the trims start going the other way minus readings ( ecm taking away fuel )
I just want to see that the ecm can respond to a rich .
If there is no fuel return rail ( return done internally in tank ) just squirt brake cleaner or easy start up the inlet ...... i just want to know lamdas and ecm can see it going rich .
At this stage now i would be smoke testing inlet manifold and doing a vac test to see manifold integrity ...... i dont know if you have the gear to do this ??
The air mass reading being down is were i want to be going , all exit points off inlet manifold need to be ruled out ........... so ..... breather pipes to pcv , brake servo pipe things like that , have you had a spray around inlet maniflod with brake cleaner to see if it draws it in anywhere.
If all this checks out as good .......next step injectors out for spray and quantity testing .
Also did you try driving with air mass un plugged to see what happens with fuel trims .
If you let me know where abouts you are in the country i could see if any of the pro diagnostic garages that are on the closed diag forums that im on could help you with carrying out a smoke test and manifold tests and so on .
Say £50 for an hours diag maybe well spent especially with someone who knows what there doing ........better than guess at this that and the other .
Im not preaching here by the way ........ near enough every week i see car coming in with egrs , injectors , map sensors , air masses , coil packs you name it 100s and 100s of pounds in parts ( guess a part squad ) and yes some garages are just as bad ...... test not guess ........test rule out ...move on .
Let us know how you get on
Lee
|