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I've yet to install the o2 sensor as I'm suspicious it's not the problem...I noticed when I pump my brakes, my o2 sensors start dropping mV and start reading towards the lean side (drop from .500 mv to .350)
The oil cooler pipe was pretty easy going as I already had the car in the service position...well actually I took the whole lock carrier off.
what turned out to not be fun was snapping two water pump bolts...thankfully my spouse bought me a tap and die set for v-day...she's a keeper.
Funny, I snapped two water pump bolts as well, including the exact same one you had the tap on. You're also the first one I've heard to describe the oil cooler pipe as "easy going". I had to remove the front engine carrier along with the two front subframe bolts just to lift the engine up to remove the rear oil cooler bolt. Luckily, the exhaust stud came out easily enough. I hope you used the Bufkin pipe, or you may have to do it again in the future.
Just for peace of mind, while you're in there, make sure you replace the alternator o-rings and the thermostat as well.
As for your engine running lean as you pump the brakes, it sounds as if the hydraulic power steering pump is putting an increased load on the engine (typically connected to the brake booster) and the ECU cannot react quickly enough. Does your RPM drop as well? If so, by how much? Rotating the steering wheel at idle should yield similar results. You should also keep in mind the engine load percentage before, during, and after these stresses.
If I were you, I'd check the throttle body, clean it, run basic function tests, and maybe replace its gasket as well. After that, I would check fuel pressure/injectors. Eliminate one variable at a time.
Lastly, I noticed you had non-OEM intake linkage arms connecting the vacuum pods and the intake manifold. I would replace those as soon as possible with proper aftermarket linkage arms made of Delrin or aluminum as they have to meet certain specifications/dimensions so the intake changeover flaps seal properly within the intake manifold.
As for your engine running lean as you pump the brakes, it sounds as if the hydraulic power steering pump is putting an increased load on the engine (typically connected to the brake booster) and the ECU cannot react quickly enough. Does your RPM drop as well? If so, by how much? Rotating the steering wheel at idle should yield similar results. You should also keep in mind the engine load percentage before, during, and after these stresses.
If I were you, I'd check the throttle body, clean it, run basic function tests, and maybe replace its gasket as well. After that, I would check fuel pressure/injectors.
As of right now the only code is P0430. Bank 2 Cat inefficiency. Given enough time, no doubt, p0174 will pop up...Watching fuel trims, the last I saw were Rich at Idle, Lean under load (multi)
I took off the TB and cleaned the build up, cleaned and inspected entire intake tubing and cleaned contacts inside potentiometer. Performed the Throttle body alignment via measuring block 60 I believe in engine module basic settings.
I noticed that on warm-up, once the secondary air shuts off, that's when the rough idle is noticable. It's not ridiculously rough however.
Regarding the power steering:
IfI turn the wheel at idle, the rpms drop maybe 50-100 rpm and stays at that rpm after I stop turning. Blip the Throttle and the idle goes back to to where it began. I can hear the strain/whine on the pump while holding light turning pressure. No air bubbles in reservoir. It's full too.
- brake assist is not working. I have to push harder to stop the car. Also, with foot on brake pedal to start car, the pedal does not drop slightly once engine starts.
- My power steering pump is always making a constant "under load" noise (you know the sound, when you're at a stop and you turn the wheels).
- when I shut off the engine I can hear something winding down for 3-5 seconds.. Either its the pressure venting out of the PCV or could it be my SAI pump?
- engine performance has dropped.
- Side note - Sometimes while accelerating I'll get a little kick of power as if fuel was starved and then gets delivered full pressure...
Could be unrelated issues, or a well documented gremlin in my A8. Please help me figure this out. Every time I see my car I forgive it like "awe I can't be mad at you".
- brake assist is not working. I have to push harder to stop the car. Also, with foot on brake pedal to start car, the pedal does not drop slightly once engine starts.
- My power steering pump is always making a constant "under load" noise (you know the sound, when you're at a stop and you turn the wheels).
- when I shut off the engine I can hear something winding down for 3-5 seconds.. Either its the pressure venting out of the PCV or could it be my SAI pump?
- engine performance has dropped.
- Side note - Sometimes while accelerating I'll get a little kick of power as if fuel was starved and then gets delivered full pressure...
Could be unrelated issues, or a well documented gremlin in my A8. Please help me figure this out. Every time I see my car I forgive it like "awe I can't be mad at you".
It's been a while, so I might not remember all the details about this issue but your recent descriptions make it seem like a fuel supply related issue, either with the pump, fuel filter, or fuel injectors. Perhaps even fuel trims or ignition timing. Can you post your STFT and LTFT values? How about group 090-093 values? You recently changed out your timing belt, so it's crucial that timing has stayed within specifications.
Does the car seem to perform better/worse/differently as fuel level changes? If so, you could look into the fuel pump(s) as primary culprits. The car uses two fuel pumps depending on fuel level.
Suggestions for right now:
Change out your fuel filter; it's a cheap part and should not take that long. You should experience immediate results, especially if yours is old.
Run fuel treatment through to clean out your fuel lines and injectors.
Install new intake linkage arms. Like I said, the intake arms should only ever be in the fully down or fully up position in order to manage the intake paths properly. Anything in between may cause unexpected intake paths and turbulent issues in the intake manifold that may cause incorrect fuel:air ratios. Imagine it as a switch; it should only ever be fully open or fully closed.
Measure as much as you can via VCDS measuring blocks at different RPMs/conditions, i.e. fuel trims, timing, mass air flow, etc.
Check brake fluid levels and perform flush/bleeding procedures.
It's been a while, so I might not remember all the details about this issue but your recent descriptions make it seem like a fuel supply related issue, either with the pump, fuel filter, or fuel injectors. Perhaps even fuel trims or ignition timing. Can you post your STFT and LTFT values? How about group 090-093 values? You recently changed out your timing belt, so it's crucial that timing has stayed within specifications.
Does the car seem to perform better/worse/differently as fuel level changes? If so, you could look into the fuel pump(s) as primary culprits. The car uses two fuel pumps depending on fuel level.
Suggestions for right now:
Change out your fuel filter; it's a cheap part and should not take that long. You should experience immediate results, especially if yours is old.
Run fuel treatment through to clean out your fuel lines and injectors.
Install new intake linkage arms. Like I said, the intake arms should only ever be in the fully down or fully up position in order to manage the intake paths properly. Anything in between may cause unexpected intake paths and turbulent issues in the intake manifold that may cause incorrect fuel:air ratios. Imagine it as a switch; it should only ever be fully open or fully closed.
Measure as much as you can via VCDS measuring blocks at different RPMs/conditions, i.e. fuel trims, timing, mass air flow, etc.
Check brake fluid levels and perform flush/bleeding procedures.
Thank you for the quick reply.
I bought proper timing tools for the timing belt so no worries there..
- Fuel filter is brand new, also the old one didn't have any junk built up inside..No correlation between fuel level and performance.
- can I use seafoam for injector cleaner? Heard horror stories/rumors on Audi's.
- aluminum pod arms failed to arrive, still waiting, but what I have is working great for now. Exact tolerences for the (smaller) inch sized arms.
I suppose I'll go for a drive and grab new STFT and LTFT data. What's stored now is Lean (Multi) on bank 2, with phantom codes for bank 1.
It's just me - data logging while driving is sketch - so give me an hour or two haha.
What's group 90, 93 display? Edit: ahhh, camshaft adjustments...I see.
i have 166k on my 4.2 and use Seaform every few months or so....i see no harm from using it. Seaform did seem to help a rough idle on our pontoon motor.
Seafoam is also standard FSI fix for knocking type noises and running issues for Mini S. Notorious for it--early FSI motor where need to re do PCV system design was a total afterthought by BMW. Enthusiasts do it almost preemptively. What it is doing on an FSI motor is cleaning intake valves some. By contrast, if you have a port injected motor (first several years of D3), then just Techron through the gas cleans both injectors and intake valves.
About only minor thing to know from when I would do Mini was simply the big cloud that you get on first drive off when the remnants of the spray/liquid go through engine or crap blown out exhaust when motor works more. Thus know on first drive off it will probably hesitate once or twice too--nothing is wrong and you just push through it with throttle. Best to drive it around block or something before handing off to another driver right away.
04-07-2017, 01:57 PM
