NefMoto

Hy guys!

I'm looking on some input on this. I have an S4 B6 V8. On bank 1 it shows partial adaption -9.4% and bank 2 partial adaption 8.6%

So almost the opposite of each other.

Now i'm wondering, is it safe to say things both banks share like MAF, fuel pressure and stuff like that would not cause this? Or is it possible for an maf of fuel pressure problem to get one bank lean an one rich?

Thanks!

Usually, yes. Look at things that are bank-specific first.

Thanks vwaudiguy for your replay!

Today i have shifted the injectors from both banks but no change.
Checked the cam adjuster timing while driving and they both follow the target.
Did a WOT log on the MAF and got 270g/s @ 6800rpm witch looks fine to me.
Fuel pressure 3.7bar @ idle
Checked for vacuum leaks

If i have time tomorrow i will swap both 02 sensor and see what happens.

Do i miss something?

The photo is after about 1 hour drive.
 

If You are only testing, easier to just swap the lambda connectors at the firewall. I'm guessing getting to the actual sensors isn't going to be especially fun.

Pressure tested for leaks? Cracks in ex manifold or exhaust?

The wires are to short for that. I changed them oud it was not to bad actually. But still got negative trim on bank 1 and positive on bank 2.


Exhaust is fine and i used an smoke machine to look for leaks. Found a very minor leak at the pcv valve. I ordered one i will replace it but im pretty sure it would not course problems on partial trims.


What is actually acceptable for trims? Am i just to anal about it? I don't get dtc's but i can clearly see that the left exhaust pipe is more black than the right one.

And when i pull the MAF connector en reset trims and go for an drive wil it still show trims or wil the ecu be in open loop?

Ecu will still show trims sans MAF. I tend to see a percent or two difference between banks or less on a healthy engine. Don't think you're being anal at all. What you have is a huge difference.

Okay good! I'm not sure if there is any more stuff i can change between banks other than the coils. Don't expect much from that as the engine pulls great but i will give it an try.

When i have the coils out i will do a compression test. If that turns out oke and changing the coils had no effect i'm not sure how to proceed anymore. Probably gonna try a new maf  ???

In addition to smoke test, You should spray carb cleaner (engine running of course) to any place that could potentially leak. The idea being that many gaskets and hoses will hold positive pressure just fine but will leak under vacuum. Or vice versa.

I've previously had leaks on the intake manifold flap end gaskets on the front of the engine and one B7 S4 which had all the bolts holding the intake manifold halves together just finger-tight. The car was very low mileage and I'm pretty sure it wasn't never removed before.

You are not anal about your trims. You got serious issue there. Also idle trims are opposite to pt trims. Both are very much appart.
GL.

Hy hopsis! Thanks, Im aware of the lose manifold issues. I checked mine and they were all tight. I did check with carb cleaner for leaks while looking at the short fulltrims but it i showed no problem's. But i will have an closer look on the manifold flap as you suggested! I did spray in that area but not really specific on the flap arm thanks!

Mmm yes i didn't really noticed that but now u say it.... I really hope to get this issue solved as i have a 6000km trip planed in 4 weeks  :P

I have seen camshaft timing cause fueling issue like this . What does MVB 90 , 92 ,93 read in Vag-Com ?  MVB 93 is the most important and it will tell you the correlation between the crank and camshafts .

Hy!

I,m sorry for my super late replay on this. Had some other stuff to deal with so didn't work on the car for some time.


I'm also not sure what to look for at this point. I switched most electrical stuff on both banks but no difference Also did some logging on various stuff and noticed the fueltrims are realy onstable. It seems not normal to me but im not sure so i also added the log here maby someone can have a look for my?

I would really like to have some input how to go further with this.

Thanks!

Bank 2 clearly has a problem.

You mean in general or timing wise?

Also the VCDS log i made is just after i erased dtc