W12 misfire, engine cuts out

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Dad's VW W12 engine. First symptom: the engine sometimes stalls at idle (did it only twice over the course of a few weeks), although idle seems generally very smooth. Second symptom: On acceleration, the engine bucks and or hesitates sometimes but mostly it runs fine. Idle is smooth. Third symptom: the engine cuts out for up to two seconds while driving then catches and runs like nothing happened.

Codes:
1. P0303, misfire cylinder 3
2. 17606 bank 1 sensor 2 (post-cat sensor)

I presume the misfire caused the 17606 DTC. I will, of course, check the spark plug on cylinder #3 and the spark plug wire from cylinder 3 to coil #3. I also plan on checking coil #3. Does that sound reasonable? Anything else I should check?
 
What year is this with plug wires? I thought these used COP. It sounds like you may be dealing with more than one issue, possibly a plug or coil or oil filled plug tube and a bad MAF or connector, crank or cam sensor, lots of possibilities.
Check the obvious then put a VAG COM Scan Tool on it. I have seen many MAF connectors with broken tabs from replacing the air filter, then it has a wonky connection and causes all sorts of intermittent issues.
 
Originally Posted by vavavroom
Second symptom: On acceleration, the engine bucks and or hesitates sometimes but mostly it runs fine. Idle is smooth.


That's exactly what my Buick did when the MAF sensor was on the blink.
 
You NEED VCDS, period.

All you're going to get here are random suggestions, and I won't contribute other than to say:

Buy VCDS and post a full system scan on the VWVortex Phaeton forum. They're very knowledgeable and helpful.

Be prepared for a very expensive service unless you have an engine table.
 
VAG-COM is an absolute must when you're working on a VW. Start browsing the 'Vortex and make friends with the local VW guru at an indie shop. I'd start looking at ignition or fuel related issues.
 
Originally Posted by nthach
VAG-COM is an absolute must when you're working on a VW. Start browsing the 'Vortex and make friends with the local VW guru at an indie shop. I'd start looking at ignition or fuel related issues.

The "local indie shop" "guru" has probably never seen a W12 Phaeton.

The VW mechanics that were factory trained on the Phaeton were trained over 12 years ago. This is not a Jetta or Passat.

The OP needs VCDS, he needs the Phaeton subforum, (the rest of VWVortex is a dumpster fire) and he needs to prepare his father for an engine-out service to replace the O2 sensors. There are 8, and only a few can be accessed while the engine is in the car.
 
Originally Posted by Trav
What year is this with plug wires? I thought these used COP. It sounds like you may be dealing with more than one issue, possibly a plug or coil or oil filled plug tube and a bad MAF or connector, crank or cam sensor, lots of possibilities.
Check the obvious then put a VAG COM Scan Tool on it. I have seen many MAF connectors with broken tabs from replacing the air filter, then it has a wonky connection and causes all sorts of intermittent issues.


You're right Trav. I must be suffering from cognitive dissonance. That engine has coils on plugs. No spark plugs wires to go bad! My list of suspects got a little shorter. I doubt it's the crank sensor because I replaced that sometime last year. I think it was a VEMO. When that one was defective it made the engine cut out intermittently when going uphill. Dad says the problem now appears maybe once during a one hour drive. So it's pretty intermittent. I don't have a VAG-Com or VCDS but I borrowed a friend's OBD 2 scanner and it retrieved the two codes I posted. I'll go over the engine this weekend.
 
Originally Posted by rooflessVW
The OP needs VCDS, he needs the Phaeton subforum, (the rest of VWVortex is a dumpster fire) and he needs to prepare his father for an engine-out service to replace the O2 sensors. There are 8, and only a few can be accessed while the engine is in the car.


I'm reluctant to buy VCDS unless my son brings an OBD 2 vehicle home. So far they all have been pre-OBD 2. I presume VCDS can show more detailed diagnostics than a regular OBD 2 scanner?
 
Originally Posted by rooflessVW
Originally Posted by nthach
VAG-COM is an absolute must when you're working on a VW. Start browsing the 'Vortex and make friends with the local VW guru at an indie shop. I'd start looking at ignition or fuel related issues.

The "local indie shop" "guru" has probably never seen a W12 Phaeton.

The VW mechanics that were factory trained on the Phaeton were trained over 12 years ago. This is not a Jetta or Passat.

The OP needs VCDS, he needs the Phaeton subforum, (the rest of VWVortex is a dumpster fire) and he needs to prepare his father for an engine-out service to replace the O2 sensors. There are 8, and only a few can be accessed while the engine is in the car.


Re: removing engine to........................

I read this and I think about a funeral service I recently attended for a WWII vet. He was a Midwest farm boy growing up fixing tractors who was an Army tanker (Armor). While his crew could do basic and some advanced maintenance on Sherman tanks in the field, his counterparts in Panzers and Tigers hardly had the same access to service. Makes my wonder if the Germans with their wonderful engineering have ever learned.
 
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Originally Posted by vavavroom
I'm reluctant to buy VCDS unless my son brings an OBD 2 vehicle home. So far they all have been pre-OBD 2. I presume VCDS can show more detailed diagnostics than a regular OBD 2 scanner?

Yes. OBD2 isn't even worth entertaining with a VW as complex as the Phaeton. Did you know it has 32 modules? It will help you pinpoint the issue, if not outright call it out. VCDS is a NECESSITY if you have a big VW. (Phaeton, Touareg, S8, etc..) You simply cannot troubleshoot without it.

Which is why I suggested it before. You'll get nowhere without it.
Originally Posted by user52165
Re: removing engine to........................

I read this and I think about a funeral service I recently attended for a WWII vet. He was a Midwest farm boy growing up fixing tractors who was an Army tanker (Armor). While his crew could do basic and some advanced maintenance on Sherman tanks in the field, his counterparts in Panzers and Tigers hardly had the same access to service. Makes my wonder if the Germans with their wonderful engineering have ever learned.

A nice story, but not the same thing.

The Phaeton, least of all the W12, was not made to be easy to service. It was not made to be inexpensive. It was made to be big, fast, and luxurious. There was never a VW like it before and will never be another like it again.

Tell me, have you ever seen a W12 Phaeton, or even a big V12, in a luxury car? The engines are big, and the space that they occupy is small. The V8 Phaeton is easy to service. The VR6 Phaeton is easy to service. Likewise a BMW 740i will never have its engine out.

I'm curious: how would you improve the W12 Phaeton's serviceability? Something a little more in depth than, "make it easier hur-dur."
 
Originally Posted by Trav
IIRC they even built a new factory in Dresden to build the Phaeton. No car in that class is easy or cheap to work on.

Die Gläserne Manufaktur, where the Phaeton (and for a time, the Continental Flying Spur) were made.

It now operates as an art and technology showcase. Wonderful to visit, if you ever have the chance.
 
Originally Posted by Trav
IIRC they even built a new factory in Dresden to build the Phaeton. No car in that class is easy or cheap to work on.

The Glass Factory was more of an assembly plant - everything was shipped as an assembly for integration.

The Phaeton was a rare sight - even in the Bay Area. Most of the ones I've seen are the V8 models. I've seen more W8 Passats than Phaetons, and certainly more A8s.
 
Originally Posted by rooflessVW
Originally Posted by vavavroom
I'm reluctant to buy VCDS unless my son brings an OBD 2 vehicle home. So far they all have been pre-OBD 2. I presume VCDS can show more detailed diagnostics than a regular OBD 2 scanner?

Yes. OBD2 isn't even worth entertaining with a VW as complex as the Phaeton. Did you know it has 32 modules? It will help you pinpoint the issue, if not outright call it out. VCDS is a NECESSITY if you have a big VW. (Phaeton, Touareg, S8, etc..) You simply cannot troubleshoot without it.

Which is why I suggested it before. You'll get nowhere without it.
Originally Posted by user52165
Re: removing engine to........................

I read this and I think about a funeral service I recently attended for a WWII vet. He was a Midwest farm boy growing up fixing tractors who was an Army tanker (Armor). While his crew could do basic and some advanced maintenance on Sherman tanks in the field, his counterparts in Panzers and Tigers hardly had the same access to service. Makes my wonder if the Germans with their wonderful engineering have ever learned.

A nice story, but not the same thing.

The Phaeton, least of all the W12, was not made to be easy to service. It was not made to be inexpensive. It was made to be big, fast, and luxurious. There was never a VW like it before and will never be another like it again.

Tell me, have you ever seen a W12 Phaeton, or even a big V12, in a luxury car? The engines are big, and the space that they occupy is small. The V8 Phaeton is easy to service. The VR6 Phaeton is easy to service. Likewise a BMW 740i will never have its engine out.

I'm curious: how would you improve the W12 Phaeton's serviceability? Something a little more in depth than, "make it easier hur-dur."

Originally Posted by rooflessVW
Originally Posted by vavavroom
I'm reluctant to buy VCDS unless my son brings an OBD 2 vehicle home. So far they all have been pre-OBD 2. I presume VCDS can show more detailed diagnostics than a regular OBD 2 scanner?

Yes. OBD2 isn't even worth entertaining with a VW as complex as the Phaeton. Did you know it has 32 modules? It will help you pinpoint the issue, if not outright call it out. VCDS is a NECESSITY if you have a big VW. (Phaeton, Touareg, S8, etc..) You simply cannot troubleshoot without it.

Which is why I suggested it before. You'll get nowhere without it.
Originally Posted by user52165
Re: removing engine to........................

I read this and I think about a funeral service I recently attended for a WWII vet. He was a Midwest farm boy growing up fixing tractors who was an Army tanker (Armor). While his crew could do basic and some advanced maintenance on Sherman tanks in the field, his counterparts in Panzers and Tigers hardly had the same access to service. Makes my wonder if the Germans with their wonderful engineering have ever learned.

A nice story, but not the same thing.

The Phaeton, least of all the W12, was not made to be easy to service. It was not made to be inexpensive. It was made to be big, fast, and luxurious. There was never a VW like it before and will never be another like it again.

Tell me, have you ever seen a W12 Phaeton, or even a big V12, in a luxury car? The engines are big, and the space that they occupy is small. The V8 Phaeton is easy to service. The VR6 Phaeton is easy to service. Likewise a BMW 740i will never have its engine out.

I'm curious: how would you improve the W12 Phaeton's serviceability? Something a little more in depth than, "make it easier hur-dur."


The short answer is yes, I have seen a W12 - even rode in the W12 Phaeton once ......................Impressive! . And I drove a 1967 Ferrari 330GTC ......... nearly bought it in 1976..................... quite a story behind that. And I have seen very many V12 (and V16) - mostly older vintage types but several Jaguar XJ12 and many BMW newer types.

The long answer will have to wait until I have more time.
 
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Dad has sold the Phaeton. It's got a little under 300k miles on it and problems have been cropping up over the past couple years. Some spare parts took a very long time to arrive. He is not yet sure with what to replace the Phaeton but he wants something a bit smaller.
 
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