BinsuJiro

After I replace the vacuum hoses, this seems like the next step. Thanks to the contributors who spotlighted the CPS as a possible culprit.

BinsuJiro

I'm glad that I can eliminate the cats from the trouble shooting process for the stalling/hot start problem, and thanks for the heads-up on the CPS.

BinsuJiro

As I stated in a previous post, I am replacing all of the vacuum hoses with HighTemp Silicone Hoses. But, while doing that, I did some more checking on why the A6 died on the road.

I don't have a clear and direct cause. My first test was going to be to check spark and spark plug condition. I found the following:

Each of the spark plug wells was filled with about 3" of oil, and I subsequently found the SUCTION PUMP to be clogged; a fresh oil leak from the valve cover, and partially clogged ventilation tubing.

My theory on why the car stalled on the highway is that the gaskets at each of the spark plug wells failed at the same time causing a sudden but temporary loss in oil pressure which activated the major oil loss computer shutdown of the engine. I was thrown off originally by the oil level on the dipstick which was well within the proper range. So, even though I got the BIG FLASHING OIL CAN WARNING LIGHT when the car stalled, I was confused by all of the possibilities, and no significant apparent loss of oil.

I'm making the following repairs:

The spark plug wires were in bad shape; I'm replacing them.

The coil pack is being replaced, and new spark plugs installed.

I'm replacing the Crankcase Ventilation Tubing, the Suction Pump and the Check Valves.

I am also replacing the two Coolant Temperature Sensors, the CPS, all Valve Cover Gaskets, and since I'm that far into the engine, and don't know when the Timing Belt was changed (used car); I'm doing belts, Water Pump, Thermostat, Pulleys and Tensioners.

Naturally, Air Filter, Oil Filter, Oil and since there was sludge on the Valve Covers, I will drop the Oil Pan to check the screen and clean it out.

The project is still ongoing; I ran out of money for parts, but will report back when the Avant is ready. The car is 14 years old, but in very good condition, and I like it. It already has new tires, struts, new heavy-duty control arms, front stabilizer bushings, stabilizer links, outer CV Joints and HD Headlights (deer killed lights; car killed deer).

After all of the above is completed, I will have to deal with the cats or the flex joints.

Airbag

Okay a couolenof things about your theory that might change your thinking.

Valve cover gaskets have nothing to do with oil pressure. That part of the system isn't pressurized. I imagine or at least hope that your oil light came on because they car stalled and you had no oil pressure.
There is no " emergency shut down" by the computer. This is not star trek

The oil in the spark plug tubes needs fixing. .

I can't remember the original issue now. !

BinsuJiro

Airbag,

Thanks for the additional information. By the time the Big Oil Can warning light came on, I had already lost power, but had never seen the Big Oil Can warning symbol before during a stall.

Maybe it was the oil in the spark plug wells that caused the stall, but I don't know. Parts for the repairs that I mentioned above are arriving in the next few days.

There was some sludge in the passages of the valve covers where the plastic tubing attaches, and the tubes themselves had significant buildup in them, but except for the varnishing of the surfaces in the area of the camshafts, there was no significant sludge found there.

But as I mentioned, I will be dropping the oil pan to inspect the oil pump and the screen.

The thread started as a HOT ENGINE START problem, and over a number of weeks ended up being the no warning stall with the oil light just after loosing power.

After being towed the car started fine the next day, and there was plenty of oil, as indicated by the dipstick. Except for the oil in the spark plug wells and rest leaking around the valve cover gaskets, I saw no other problem.

When I removed the camshafts to replace the VC gaskets, I pulled the removable piston in the CCT to see what was going on inside that. I didn't notice any indication of sludge buildup and none of the oil passages were clogged. The camshaft bearing caps had no surge in their passages.

I'll know more when I drop the oil pan.

Thanks for your help and advice; best regards,
Vincent

meternerd

I'd bet on the coolant temp sensor. No codes but WILL NOT START hot. Black smoke came out of mine when trying. Let it sit half an hour and all was well. Two sensors in one unit, one for indicator and one for ECS. Cheap to replace and easy, too.

BinsuJiro

Well, a lot has happened since the last post quoted above.

I have completed the following work:

New CPS, new valve cover gaskets; cleaned and replaced screens and pads on timing chain tensioners; replaced valve cover gaskets; installed new spark plugs, spark plug wires and coil pack; replaced all vacuum tubes and hoses; replaced check valves and suction pump; installed new temperature sensors (upper and lower), thermostat and water pump; installed new timing and accessory belts, pulleys, idlers and tensioners; restored oil to components by turning over engine with fuel pump fuse removed and installed new anti-freeze.

After all of this, I replaced the fuel pump fuse into its socket and tried to start the car; NOTHING! Checked fuel; fuel was OK, but there now is no spark being delivered from the coil.

I'm going to be optimistic about the coil and say that since it is new, it must be working, which leads me to the two electrical components connected to the coil...the capacitor and the ecm via the five pin connector.

I checked all of the fuses in the main end of dash fuse holder, and they tested good.

Can anyone think of anything that I might have missed, before I move on to the ECM in the air plenum? Is there an adaptation process for the new CPS? And, if I have to move on to the ECM, how can I record the settings and identification info from the module with a ross-tech VAG-COM device, since the car will not start?

Kris Hansen

Silly question, have you replaced the ignition switch at any point in this? Did the car run at all before all of the above work?

BinsuJiro

I have not replaced the ignition switch, and the car ran before the work.

As mentioned in previous posts in this thread there were various problems having to do with hot engine starting and with hot engine stalling. And the last time the car stalled when the engine was hot was after the valve cover gaskets blew out because the suction pump was completely clogged, and each spark plug well filled with oil. Whether the stall was due to current escaping the plugs to ground because of the heated oil or there was another cause, I cannot be sure.

At one point in the testing prior to the work, there was a CPS fault in the DTC's. I didn't get a chance today to test the ignition switch or the voltage at the five pin connector for the coil pack.

Thanks for your interest in this issue.