BMK 3.0 TDi hunting erratic idle revs ( Have I got the most lemon A6!!! )

[gupsterg]

tip if you disconnect the airmass it will deactivate egr so try starting it with the airmass unplugged and see what happens

Will expand what happened later ... but can you tell me what Ohms readings should I be getting to check MAF... thanks

Looking at the post... Link:- audi 3.0tdi engine measurement blocks

Is the above MVB 10 something to look at as well

[a8 tech]

Off the top of me head no, however you could check actual and specified with vcds but remember if the engine idles for to long egr will kick in and alter the values so rev it frequently for a true value

If the egr is playing up you should be able to see a constant out of tolerance airmass reading

If the airmass is ok and egr ok then your back to injection deviation from either worn injectors or pressure in the rail but thats easy to check by looking at mvb's for actual line pressure

If the pressure is ok then again you are left with the injectors or compression loss

Now if the injectors are removed the brass O ring must be replaced as this compresses when re tightened and could allow blow pass compression leakage

also each injector is calibrated to the ecu and therefore if replaced should be set up but for simple swapping around to eliminate it should be fine

3.0l V6 TDI (BKS/BMK/BUN) - Ross-Tech Wiki

Again all speculation but pointing you in the right direction

[as400]

Better the devil you know?....sorry I havn't read the whole thread, have you taken it to Audi to see what their view is?

[a8 tech]

lol

[gupsterg]

I'm trying to exorcise the devil...

A8 is > than dealer

[as400]

Ah sorry had no idea!....

[gupsterg]

Ok guys... since about 11 am today... Zesty the A6 is

On first start of day/road test without MAF harness connected... there was rockying after the normal rock of cranking of engine... revs fluttered but very quickly sorted themselves out way better than before/quicker

Whilst on TD... stopped when temp reach 70c ish... started her up =

Then when she reach normal temp (90c ish)... stopped/started her up =

Came home... stopped/started... all well... at no point did I see idle smoke at start up/driving/stopping & checking... so I believe the one in video may have been throttle/maf related or just normal morning thing... but today and other day when she no smoke temps been low...

Then I let her cool... when she reach between 90/70 line, start her up = ... then let her cool between 70/50, start her up =

Then rang for best prices on MAF... but will wait until get info on doing Ohms test on MAF...

Then went to do my usual trips... on all starts ... surprising thing was usually with MAF I thought power loss was a sign of one gone or going...

But Day 1 with Zesty the A6! having no MAF connected been a full success IMO...


The MIL light came on

Did scan these were the faults...

-------------------------------------------------------------------------------
Address 01: Engine Labels: Redir Fail!
Part No SW: 4F0 910 401 L HW: 4F0 907 401 A
Component: 3.0L V6TDI G000AG 0040
Revision: --H01--- Serial number:
Coding: 0011772
Shop #: WSC 02334 785 00200
VCID: 254BDA7FECF6CC30723

2 Faults Found:
16488 - Mass Air Flow Sensor (G70)
P0104 - 001 - Intermittent
Freeze Frame:
RPM: 0 /min
Torque: 234.0 Nm
Speed: 0.0 km/h
Duty Cycle: 80.9 %
Voltage: 11.02 V
Absolute Pres.: 999.6 mbar
Mass Air / Rev.: 0.0 mg/str
Temperature: 13.5°C

16486 - Mass Air Flow Sensor (G70)
P0102 - 001 - Signal too Low
Freeze Frame:
RPM: 882 /min
Torque: 113.1 Nm
Speed: 0.0 km/h
Duty Cycle: 80.9 %
Voltage: 11.93 V
Absolute Pres.: 1009.8 mbar
Mass Air / Rev.: 481.8 mg/str
Temperature: 11.7°C

Readiness: 1 2 0 0 0

-------------------------------------------------------------------------------

As I've been doing so many videos... runs with laptop checking & logging MVB's...

I've now not done any MVB's on the MAF... so tomorrow going to clears faults before she go for MOT, so no MIL and connect MAF back...

If problem return which I think it will... will disconnect... again!

[a8 tech]

Ok so now we can look at the possible cause

Egr flow excessive, poor air mass, poor air filter, fuel unbalanced

Remember disconnecting maf turns off egr regulation and defaults fuel mapping

Still no party just closer

See Mass Air / Rev.: 481.8 mg/str default value very high and will make the running smoother because you have no dirty egr gas going back into the cylinders

Note:> To all watching this thread, I answer on the fly and have yet to actually sit down and study the data so please do not think my diagnosis is 100% spot on because its not and i am just trying to move this on a little quicker than it has been and give options for better diagnosis route

and i dont have the vehicle in front of me which would help

[gupsterg]

Air filter new... genuine.. done in Jan by me.. I owe you a visit with a hamper of goodies

[Rosscow]

Sounds like progress Gup, keep at it it