codewhore

Here is the background. The car (2004 Audi S4, 6 MT, about 170,000 km not miles) has been running running great lately. I had the car out for a drive the morning my problems all began. Little bit of city criving, a little bit of highway, nothing really aggresive just a nice casual with a bit of spirited driving. As I am slowly driving through a parking lot to drop a friend off at work the car starts to stumble a bit and the check engine light comes begins to flash. Hmmm, I have been through this before, just 2 months ago actually and again back in February, probably just another coil pack. In fact I have 6 new coilpacks sitting at home just waiting to get installed so all of them are up to date.

I am only about 1km from my work so I continue on so I continue on without anything other than the rough running that seems normal when you have lost a coilpack. Park the car, go in to work for about an hour or so and come out to my car. I try to start the car and it just won't fire. This is different than any coilpack I have seen before. Cranks fine seems like it wants to start but just won't catch. Open the hood and there is the smell of cooked electronics especialy near the front of the engine on the driver's side.

I call the girlfriend and have her pick me up, we go get my coilpacks from home and my tools and I head back to the car. I replace all the old coil packs and try starting the car again. Still it doesn't start right away but it does catch and is idling but a bit rough. I think maybe I fouled the plugs a bit before so I figure I should just drive the car around the block and see what's what.

This is where things begin to get really odd. I go to move out and the gas pedal is basically ignoring what I am telling it to do. I can pump it or hold it down to the floor and it appears to be ignoring me. After repeatedly stoping and starting the car it actually appears to be trying to do what I say but can't. The idle is also on its own floating between 800 and about 1200 RPM.

I get the name of an independant Audi guy that comes and scans the car. First scan shows a lot of crap including a failed coilpack on cylinder 5 which is basically where I had that strong smell of dead electronics. But here are the other codes:
19497 - Powertrain Databus: Implausible Engine Temp. Message from Inst. Panel
P3041 - 004 - No Signal/Communication - Intermittent

16840 - EVAP System: Very Small Leak Detected
P0456 - 002 - Lower Limit Exceeded - Intermittent

17776 - Cylinder 5 Ignition Circuit: Short to Plus
P1368 - 001 - Upper Limit Exceeded - Intermittent

16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - Upper Limit Exceeded - MIL ON

16689 - Cylinder 5: Misfire Detected
P0305 - 001 - Upper Limit Exceeded - MIL ON

17072 - ECM Power Relay Load Circuit: (J271): Open Circuit
P0688 - 004 - No Signal/Communication - MIL ON

17944 - Camshaft Timing Adj. Bank2 (N208): Open Circuit
P1536 - 004 - No Signal/Communication - MIL ON

17936 - Camshaft Timing Adj. Bank1 (N205): Open Circuit
P1528 - 004 - No Signal/Communication - MIL ON

19475 - Valve for Exhaust Flap 1 (N321): Open Circuit
P3019 - 004 - No Signal/Communication

01039 - Coolant Temperature Sensor (G2)
30-10 - Open or Short to Plus - Intermittent

01314 - Engine Control Module
49-10 - No Communications - Intermittent

Now some of these codes were there before from a previous scan done at the dealership and they dismissed them as saying that the car is really sensitive and will normally generate codes but unless they throw a CEL then to just ignore them.

Anyway we cear the codes, start the car let it idle for a few minutes then try reving the engine very slighltly. As the car warms up it appears to respond better to the throttle but I never rev it past 2000 RPM. There are the codes that come back:
19475 - Valve for Exhaust Flap 1 (N321): Open Circuit
P3019 - 004 - No Signal/Communication

17944 - Camshaft Timing Adj. Bank2 (N208): Open Circuit
P1536 - 004 - No Signal/Communication - Intermittent

17936 - Camshaft Timing Adj. Bank1 (N205): Open Circuit
P1528 - 004 - No Signal/Communication - Intermittent

19497 - Powertrain Databus: Implausible Engine Temp. Message from Inst. Panel
P3041 - 004 - No Signal/Communication - Intermittent

01039 - Coolant Temperature Sensor (G2)
30-10 - Open or Short to Plus – Intermittent

Admittedly I tried the exhaust mod about a month and a half before so the one code made me think it was a small vacuum leak. I had installed screws to block the lines but left the line disconnected. I reconnected the lines and tried the car again but no change. The car was then loaded on a flatbed and taken to my independent mechanic.

So far they have done a bunch of trouble shooting including testing various points of the harness for continuity and proper voltages where they can, checking the fuses/relays. They even were able to plug a new set of cam adjusters into the harness and tried running the car after clearing the codes. Now this would not change the way the car was running because the new adjusters were not actually installed in the engine but they should not throw the open circuit code, which they did.

We are at a crossroads now for what to do next? We have no firm idea what has happened, it could be a tensioner that has gone and the chain has slipped but that does not explain the open circuit code on the adjusters, they should be throwing out of range or something similar. The #1 suspect right now is that the ECM is faulty. Of course this is no guarantee but before I start down this path is there anything that anyone can suggest to try or any other ideas.


Shawn

advancedautomotion

Sounds like you toasted a harness. I'd do a visual on the entire harness starting with the large bundle of wires coming out of the firewall.