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
- They get paid by the job so a quick fix is best, and they like to make an educated guess and go in that direction
- They’re full of bias to always stick to their diagnosis, since there is pressure on them to be right. There’s the perception we are going to them because they know more, so they feel pressure to be right. Reality is we go to them because we don’t have lifts and tools or time.
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.
Looking to pick up some Volk TE37SL track wheels. Which color?
Pressed Double Black
http://i.imgur.com/3xQ1G66.jpg
Pressed Graphite - I think I like this one
I would go with one colour. The contrast just makes the wheels look little.
Love these by the way. Great looking and light as heck
Oh joy, my oil temp sensor has decided to retire. That’s not getting changed until the next oil service.
What part of NC again?
Charlotte
Replaced evap purge control valve today and it didn’t fix the codes so I think there’s a wiring problem. Harness connector read 10V with car running. What else can I check?
Edit: Looks like the connector was not fully seated. Cleared the codes but I still get P2404.
Is 13.335 volts too high?
Codes:
009220 - EVAP Leak Detection Pump Sense Circuit
P2404 - 002 - Implausible Signal
Freeze Frame:
Fault Status: 01100010
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 138032 km
Time Indication: 0
Freeze Frame:
RPM: 1552 /min
Load: 25.5 %
Speed: 12.0 km/h
Temperature: 63.0°C
Temperature: 28.0°C
Absolute Pres.: 990.0 mbar
Voltage: 13.335 V
001092 - EVAP Purge Control Valve (N80)
P0444 - 004 - Circuit Open
Freeze Frame:
Fault Status: 01100100
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 138051 km
Time Indication: 0
Freeze Frame:
RPM: 5571 /min
Load: 65.9 %
Speed: 74.0 km/h
Temperature: 97.0°C
Temperature: 37.0°C
Absolute Pres.: 990.0 mbar
Voltage: 13.335 VAny events worth attending in the area?
Where are you located? I haven’t really attended much except for a few GMP hosted events. I’ll be doing some track days at VIR and CMP in the near future though.
Got my secondary airbox inlet sorted the other day. It’s nice and sealed/pressurized with a 3" hose input now.
Just a bit south of the city. Haven’t spotted your beast yet as I’m in Matthews for work during most of the week. I’ve seen a few B6/7 A/S4s but that’s about it. I know Carolina’s Audi chapter gets together now and then, but I haven’t made any of them yet.
Did you have that piece water-jetted? Or was it an off-the-shelf part?
I used a brake duct flange and trimmed it to fit in the box. Used rubber cement to bond it to the inside of the box and flowable silicon sealant to seal it on the other side. Allstar ALL42160 http://www.amazon.com/Allstar-ALL42160-Diameter-Mounting-Flange/dp/B006K8KG8W/ref=sr_1_fkmr0_1?ie=UTF8&qid=1446565976&sr=8-1-fkmr0&keywords=brake+air+duct+flange
Easy-Button…love it!