The car had recently been serviced and has nothing major due for service. All of the problems occurred after I did a brake pad change though I don't think the engine 'jumpiness/hesitation' is related.

After doing a brake pad change I took the car out to bed the pads. Foolishly I had not pumped the pedals to make sure the pads couldn't slide out and one did. While signalling to move onto the shoulder I hit the flashers and got nothing. I came to a gentle stop went back picked up my pad and slowly went home.

I replaced the pad and went back out. Got the temps up fairly quickly and it has been a long time since I bleed the brakes. At one point the pedal went to the floor, somehow hooked on the plastic, and I was forced to gas it hard to avoid coming to a stop while flipping up the stuck pedal with my left foot.

So here I sit now. The brakes work very well (unless I've been slightly sporty with lots of braking) but I have no flashers and the ESP light is on so the system is turned off and I can't turn it on. I checked the fuses for the ESP and the hazard lights and they were fine. I even swapped them for good measure and no joy.

Any suggestions on fixing them?

I'm also concerned that the brake pedal went to the floor based upon subsequently reading this post
http://www.audiworld.com/tech/wheel139.shtml
It covers non-ESP cars rear pads and says DO NOT get the pedal to the floor as you can damage seals in the master cylinder. I've had no problems in the 1.5 months since so I doubt I've done so. Can anybody back that feeling up or tell me how to double check?

Why do ESP cars need a VAG-COM while bleeding? (I admit this is probably a newbie question but fits in nicely here)

Onto the other problem. Under 1/3 to full throttle application in 2nd, 3rd, or 4th gear the car 'hesitates/jumps' below about 4.5k rpms. This also occasionally occurs in 1st but isn't noticeable really. The car feels like it is cutting the power, the feeling is akin to riding a motorcycle with little bit of gravel underneath-it feels jerky. After reading some other car forums etc. I've seen explanations all over the place from gaskets, to air sensors, and on. Any thoughts?

 

any thoughts on what problem this is?

 

That's a tough one to diagnose over the internet.
Maybe messed up the ABS Pump/Module which is utilized by the esp system.

 

OK so new info. I finally got time to pull the right front passenger wheel. There is a significant amount of grease behind the rotor. It seems to be lined up with the first bend in that rubber cover over the joint. It covers the inside of the calipers and a lot of the parts in the area. Any idea what this grease is or where it came from?

 

Your CV boot came apart and the grease is from your CV joint. Do you hear any clicking when you turn the wheel? If not then your CV is still fine you just need to replace the boot. (about $30). If it does click you might need too replace the actual CV joint as well. I need to do that in mine.

Josh

 

I did my boot yesterday. The guide on this site isn't very good and incorrect in a few of the tools. for example you need an M10 not M8, you also need a 17mm allen key not the 14. There's also a few tips I would give.

That said I did the joint and cleaned the area around it that had received a nice dousing of grease and no joy on fixing the traction control problem. I was hoping dirt or something had gotten on it and a simple cleaning would help.

 

Maybe a wheel speed sensor?

TC issues usually won't throw CE light because it doesn't affect emissions.
BUT, you may still possibly be storing a non-generic code for the ABS system. Get a VAG-COM and see or just take it to the dealer pay the diagnostic fee and save yourself the headache.

 

OK here are the current faults that are possibly applicable. I also bought the Bentley manual at the same time and many of these have multiple fixes/further tests. Given the brief history are there any shortcuts or things to try first?

Address 01: Engine Labels: 078-907-551-AZA.lbl
Part No: 8D0 907 551 H
Component: 2.7l V6/5VT G 0003
Coding: 06711
Shop #: WSC 25061

6 Faults Found:
17771 - Cylinder 3 Ignition Circuit: Short to Ground
P1363 - 35-10 - - - Intermittent
17965 - Charge Pressure Control: Positive Deviation
P1557 - 35-10 - - - Intermittent
17521 - Oxygen (Lambda) Sensor; B1 S1: Internal Resistance too High
P1113 - 35-10 - - - Intermittent
16805 - Warm Up Catalyst; Bank 1: Efficiency Below Threshold
P0421 - 35-10 - - - Intermittent
16815 - Warm Up Catalyst; Bank 2: Efficiency Below Threshold
P0431 - 35-10 - - - Intermittent
16826 - EVAP Emission Control Sys: Small Leak
P0442 - 35-10 - - - Intermittent
Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 8D0-907-389.lbl
Part No: 8D0 907 389 E
Component: ABS/ESP allrad D36
Coding: 04395
Shop #: WSC 06435

1 Fault Found:
01422 - Hydraulic Pump for Electronic Stability Program (V156)
35-00 - -

 

Have you tried replacing the coil pack on cyl 3? If not, swap it with another cylinder, clear codes and see if this code follows the NEW cylinder.

Boost leak, pressure test and see what you find.

Passenger side primary O2 (upper, behind air box) looks to be going bad.

Do you have piggies or aftermarket down pipes?

Check the gas cap, ensure it's tightly screwed down. If not, consider replacing it. Gas caps are usually the cause for this code. Replacing it is a cheap second step after ensuring it's tight.


I doubt any of these codes have to do with your brakes, but they may be related to the other issues with your car.

 

Follow up on the cylinder 3 short to ground issue. It turns out the wiring harness is run from the ECU and along the fire wall. Also in the fire wall was a screw. The wiring had rubbed against the screw enough that it had rubbed through the shielding.

Very tough to solve and big kudos to European Cars Ltd. in Houston who discovered it, solved it, and prevented the issue from happening again in the future. I can't recommend those guys enough for this and other issues.