Hello anyone..
Those day I have crazy problem with this car...
first of the the MAF sensor wiring fail which creat a wrong reading make the fuel trim going too rich...
after fix that problem my fuel trim on bank 2 going normally the LTFT most of the time going from 0 to 3% positive which mean the engine is running in good condition..
but some times, cold start the fuel trim go all the way down to -25% at bank 2 then sit there... the problem is intermittent, some time it has, some times it doesn't, SO I don't know what is going on..
I swap the ME 7.1.1 from bank 1 to bank 2 problem same So I'm guessing wiring issue some where?
it can't be mechanical issue because if mechanical issue it will happen all the day long right?
I did a smoke test and can't find any leak also..

 

Not sure if a vacuum leak would be the problem.

Since you are doing the smoke test in addition to where are you started. On the right hand side behind the intake manifold 13 mm vacuum line should also be smoked. The vacuum pump side is the primary site for the brakes which you just tested. The right side 13 mm vacuum line as you sit in the car is for the EVAP side. This gets the smoke more directly into that section. This is worth the extra work to double-check everything.

 

The MAF sensor as you stated is worth double-checking. Perhaps the sensor wires need cleaning as well ?

Another culprit could be an O2 sensor?

 

NG:

The two primary causes of a P2190 are:
Defective MAF output at idle (# 1)
Dirty air filter (# 2)

I am curious why you switched ME7.1.1? That is extraordinary. And I expected it would not make a difference here.

Did you swap MAFs Left to Right?

Some basics about EMS and engine idle.
1. At cold start, the O2 sensors do not impact idle fueling until about 105*F ECT. Before that the ECU is fueling to from a table and direct input from the MAF.
2. A MAF delivers a frequency signal to the ECU in Hz. These frequency signals have a correlation to fuel quantity the ECU delivers from the table. The ECU will match the Hz received and choose that fuel time to deliver to the injectors.
3. A typical MAF delivers approx. 1 gram/sec/Cyl vol x # of Cyls@500 rpm. So, this is a 6 cylinder engine at 3L you should be delivering approx. 3 grams of fuel/sec on the leftside Bank 2 @ 500rpm. Can you measure that?
4. As the engine warms up past 105*F, the ECU closes loop.

So, with these factors, if the MAF is falsely reading a higher frequency at cold idle, the engine is running very rich (could be the same with a dirty filter). When loop closes, the fuel trims will jump to rich and I am guessing this is when P2190 is set on your dash. With a sensor like the MAF, sometimes it can get lazy when it is failing and other times it might work normally.

Take a look at this MAF graph. It shows typical MAF output frequencies from less than idle to past redline. Idle is around the 3000 to 5000Hz range. As you can see by the slope of this curve the low frequencies around idle can be off by a very small amount yet cause huge amounts of over (or under) fueling as the ECU will chose a fuel delivery based on the Hz signal it receives from the MAF (Right or wrong).




So, if this were my car with a P2190, first swap MAFS and see if the problem follows to the right side bank. MAFs can have a failure in only some places along its curve. It can also fail completely. Since it appears the engine is running at all other RPMs and operation conditions, I would eliminate the MAF FIRST before pursuing anything else.

 

NG:

I should mention that if you switch MAFS and the problem follows to bank 1 it will produce a P2188 (not a P2190).

 

@BWings I swapped the MAF from bank 2 to bank 1 and the code doesn't change...
One thing I found out is the spark plug is not original Bentley, it something VAG NGK with diffirent part no compare with the bentley one.
Maybe I will try to change the spark plug and Air filter first...
I will order Autolite XP3923, I have very good experience with this brand, and the BMC air filter ( did anyone try it yet)
It will take a month to come to vietnam... I will keep you guy update later.. hizz

 

@1eapplebaum would u please take a picture of that.. I will smoke this then let you know

 

NG:

If you are confident the MAF on bank 2 is good, and you have a clean air filter, then the two next possibilities are fuel pressure and air leaks PAST the MAF.

Looks like someone recommended spark plugs. This is way off track IMO. I would not put in Xp3923s in this motor. XP3923s are an Autolite generic cold plug that is cross referenced for hundreds of cars, even Harleys, but Autolite doesn't have the broader/better range of plugs for some engine designs like the W12. So, Autolite recommends a plug that approximately fits the need.

If this was a NA motor like the Audi A8 it would be the XP3924 recommended. Since the 3923 is the colder plug, cold plugs are correct for a turbocharged engine and cold plugs are at their worst on cold startup idle, but you DO NOT have a misfire problem at idle. You have an overfueling problem. My concern if you continue to introduce replacement parts that are poor matches like the XP3923, you will be introducing more and more variables to future problems. Then diagnosis gets harder and harder on future issues.

If it were mine and at this point:

1. Look at fuel pressure on bank 2
2. Look for air leaks past the MAF
3. There is an O-Ring seal on the snorkel past the MAF and connected to the turbo neck. I've had to replace both of those.
4. Look for hose connections to the intercooler before and after. Make sure the 4" tube elbows are not slipping off their connections.

Best of luck to you!

 

@BWings I think I need to replace the plug because the the previous owner already change the plug and it is not belong to the car hizz.. diffirent part no from NGK
so what plug I need to change I want to put in the right one.
Thank you

My fuel pressure on bank 2 and Bank 1 constant at 55psi
regards

 

NG,

This is what I am talking about on the Autolite XP3923. Look at this site. There are 12 PAGES of cars and motorcycles listed as cross references for this spark plug. The correct plug for a W12 is an NGK double platinum and it fits only one car.

https://www.jegs.com/i/Autolite/417/XP3923/10002/-1

 

@BWings so if I fit that plug I will have numbered of issue right?
so the NGK is cold plug or hot plug? can I buy them from Rockauto?
would you please give me the correct part no for it.. thank you

my car some times it has random missfire at cold start also.. I guess maybe because of the Wrong Plug they put in

 

NGK PZFR6Q-11 Laser Platinum is the correct factory recommended cross over to NGK. The factory does not recommend iridiums in this engine, but the equivalent NGK iridium is BKR6EIX-11 and I know some shops are putting in the iridium instead of the platinum.

On fuel pressure, looks like the regulator is good if you are maintaining 55psi, but you need to measure the fuel delivery at the injectors. Look at pulsing. Sticking injectors at idle can contribute to this problem, or even one bad injector on bank two could be sticking open on idle. Then higher RPM with higher deliver rates causes it to stop leaking. A single injector sticking before closed loop and the ECU has only one choice to measure the bank as rich.

 

@BWings thank you alot..
So I wonder what is the benefit of Iridium over Platinum? in your recommend what will you put on, I saw Iridium seem more expensive ... does the more expensive the better it is?

and how can I measure the Fuel delivery of injector? VCDS or need any special tool?
thank you

 

NG,

One other thought on the P2190 - if you've had the intake manifold on and off for different reasons are you sure about the gasket integrity? This gasket is prone to leaks and should be renewed every time removed and intake manifold bolts torqued properly. A leak here could cause a rich fuel issue and it might only be at one bank 2 port.

The gasket fits where the blue tape is in this picture.



If instead of removing the entire manifold, yours was disassembled on each side, then those gaskets too can contribute.

 

Iridiums plugs last longer than double platinums if they hold up over time, but I have experience with them in high compression engines and boosted engines, because the tip is so small, they can get burned/broken off. If they break off in the engine hopefully they pass through into the exhaust without any damage. But that plug can continue to fire only now on a gap that is now double the needed gap...about .080". On a recent plug change in a V8 I found 3 out of 8 plugs with broken off tips. This is probably why Bentley recommends the more durable platinums, but they need to be changed about every 40,000 miles. Iridiums, if they hold up can last 100,000 miles.