Well apparently the REAR O2 sensors were crossed. Jake pointed this out so thanks for that. This took care of the codes and the crazy opposing STFT readings.
I also have reliable LTFT data to go off of now, which is showing +6% on bank 1 at load and -1.2% at idle.
STFT bank 1 is constantly fluctuating +/- 5%
If a vacuum leak was causing this wouldn’t I see positive LTFT @ idle? Or am I misinterpreting how LTFT is calculated on Audis?
So sorry I meant to reply like 5 times ago. Good to see you got the inssue all sorted out. It would have taken a lot of work to find the crossed wire issues.
The range of the bank to bank LTFT is best started by checking the instant fuel correction data on each side. To have one side +6 and the other -2 is a little out of range but can be effected by a large amount of things. The 02 age being one of them.
Good news, injector flow rates were all over the board and the filters were clogged with sludge. I will have them back in the car tomorrow or Friday so we will see.
Who did you have test/clean them?
How long did RACECITY take?
What’s the process?
What’s the cost/injector?
Thanks
It would have a been a 2 day turnaround but he didn’t have enough of the lower bushings for our injectors so he had to order more. It ended up taking 4 days with the shipping time for the additional bushings.
Cleaning process is detailed at http://www.racecityinjector.com/fuel-injector-cleaning-process/
He charges $22/injector. Normally you just ship to him but I’m local so I just dropped them off with him. Details are on the website.
Edit: $25/injector for ours since they are DI
Did you consider buying new injectors and selling these ones?
Yeah but I didn’t want to spend $800+. I have another vehicle so it’s not an issue if the car is down.
So here are the before/after flow results of my fuel injectors. Looks like 2 of the injectors were doing pretty poorly for flow and spray pattern.
http://i.imgur.com/Moyirs0.jpg
The guy said the sludge in my filters seemed unusual to him, but he mostly works on marine engine injectors so this might be normal for GDI fuel injectors. It almost sounds like carbon buildup INSIDE of the injectors. Which I don’t know how that would be possible… Maybe I just ran into some filthy fuel? I did notice on one of the injector ports there was a light layer of what looked like carbon which made it very difficult to remove the injector. I’m going to replace my fuel filter and cut open the old one tomorrow just to see if there’s anything funky in there.
One thing I ran into while removing the injectors was MORE FUCKING WALNUT MEDIA. Almost every injector I removed pulled out a fair amount of walnut shell media with it. Shop I paid $800 for a carbon clean: Thanks again for just spraying walnut media all over my fucking engine bay and not bothering to clean it up. I have found more of that shit every time I’ve opened the hood since they did the carbon clean service. I’ve had to stop and vacuum shit every time I’ve pulled the intake manifold to prevent the walnut media from going in my intake valves. I even found it in my spark plug ports when I checked them. Just blatantly fucking careless and it makes me want to never go to that shop again. Well I found what I think was the last pocket of that shit behind the oil filter housing line thing so hopefully I won’t see anymore of it.[/endrant]
MMMMMmmmmmmmmm clean injectors
Well you spent what… 250 including shipping? And you car is down 2 to 4 days while that happens?
My question was did you consider buying new and selling your old ones. Not buying new and throwing the old ones in the garbage.
I. E. Sell 4 each to 2 a4 owners for 300 a set. 600 bucks.
Net cost to you for brand new injectors = 200
Zero downtime
Not sure if that’s accurate pricing on the used market value
Yeah I considered it but didn’t want to deal with selling the injectors. The guy who performed the service is local so I spent $200, no shipping. Down time wasn’t a problem and it gave me time to do some other things I’ve been wanting to do:
nice. I’m thinking for me or other people…what makes more sense
maybe jake@JHM would know whta the market is for the big injectors
No more fluctuating idle 
That feeling when you fix a problem after troubleshooting for months!!!
I’m going to go celebrate.
Fuel trims are looking nice so far. STFT is staying between -/+ 5%.
Need more driving time to get a realistic LTFT.
Just wanted to comment on some very good lessons I learned throughout the last couple months trying to find the cause of the rough idle.
Don’t be a parts changer - This can be an effective method of fixing problems, but it can get expensive very quickly because you are essentially guessing. If I would have listened to someone who fixes cars professionally I would have bought a new intake manifold.
The pros can be wrong - The first time I took it into a very reputable shop they looked fuel trims and said it MUST be a vacuum leak. They looked for vacuum leaks with a smoke machine and found nothing. They still told me it MUST be a vacuum leak or that the car just wouldn’t idle properly without the manifold flaps. Most recently another tech at the same shop looked at my fuel trims and guessed that my intake manifold was bad… ???
Use data to make a diagnosis - I came to find out these techs were only looking at short term fuel trim. What they missed is that bank 1 was in a lean condition at load and calling for +6-8% fuel under load. This data eliminates the possibility of a vacuum leak if you pay attention to the LTFT @ idle, which was around -1%. A car with a vacuum leak is going to ADD fuel to compensate for the unmetered air entering the system at idle. My car was not adding fuel at idle.
So what components can we target with the data available? Since bank 1 is showing the lean condition, we look for only things that can cause a lean condition on that bank downstream of the throttle body:
high pressure fuel pump - we would get a code if pressure was low, but I still checked it and it was within a good range and matched bank 2.
oxygen sensors - I checked the voltage ranges on these and they seemed to be good
fuel injectors - This is the only component left in the chain that could cause a lean condition. Unfortunately it isn’t easy to test these while they are in the car.
Easier in hindsight obviously. The problem with shops is
It’s great when you can engage with someone who is a true expert on a particular car. There used to be rs trained technicians or r8 trained technicians in dealers who you’d hope would be ‘expert’. I find jhm is great because they’re worked on about 100 rs4s, and have remotely diagnosed 100 more. They also own one. If you are a good customer they will give you some time to give you some ideas.
Jake definitely helped me a lot during this process and eventually helped get me going in the right direction. He probably spent 2 hours on the phone with me in the last couple months. I Can’t thank them enough for that.
Ok got some new codes to troubleshoot. My guess as to the cause is that the system is seeing more fuel now and perhaps is not “used” to it.
009220 - EVAP Leak Detection Pump Sense Circuit
P2404 - 002 - Implausible Signal - MIL ON
004416 - Oxygen (Lambda) Sensor; B2 S2
P1140 - 008 - Internal Resistance too High - Intermittent
P2404 means the evap valve is either improperly connected or bad, right?
Bank 2 is reading rich and pulling about -5% on the LTFT @ load so I think replacing B2S2 is wise. Especially since that sensor is probably a Denso brand that I put in right after I got the exhaust. The other Denso sensor was already replaced with OE. Note to self: don’t cheap out on O2 sensors.
So I finally got a chance to thrash on the new 3R clutch and lwfw after break-in.
Wow, what an excellent upgrade. It really gets the power to the ground compared to the stock clutch. I used to have slippage on a high-rpm 1-2 shift. Now it just grabs and goes.
Being in North Carolina you’d think there would be ample opportunity for test-n-tune drag racing events. Not quite. Most of the tracks within 2 hours of me are 1/8 mile. There’s really only one 1/4 mile track within reasonable driving distance and they don’t really do open track or test n tune events. They have one in mid-november but it sounds like a million people are gonna be there and I don’t really wanna deal with that kind of shit.
Ah well, I’ll find somewhere to drag race this grocery rocket.
komseh can you make a master thread on just the injectors. I have seen this lots and lots with the FSI cars. The v10 cars kill there injectors with carbon easy. There have been several RS4s that have had knock and missfire issues fixed by just replaceing injectors.
This was a big thing in the mustang platform. You would see flow testing for injectors and some of them were way off. This would cause power issues and could lead to motor damage.
Great update and thread.