[bazagee]

I have a 2005 3.2l V6 baseline model with 80K. It just started to have intermittent rough idle problem as the temps got colder. It set some codes for miss firing on all cylinders. The missing might be from cold startup or more likely after a restart once the car was at operating temps.

I took it to the dealer (whom I trust but have some big miss-givings about his shop personal - even before this).. they told me what the codes told them about the mis-fire and said I should take it home after they resetting them. I told them it will start doing it again and shortly got another phone call saying the tech took it for another ride and yes it was missing now.

At pickup that day the tech told me (and I may have lost some of the conversation here or be mis-quoting a bit), that he found the valve timing was out which had caused the missing in all cylinders. The intermittent nature he stated was caused by an intermittent oil blockage a mechanism designed to alter the valve timing. They said the contaminants could be caused by not changing the oil frequently enough or from short distance driving conditions. I don't live far from work or where I drop my kid off for school so I do, do a lot of short hops.

They said they had put Sea foam into the oil and asked me to take it for a good drive for 200km bring it back and they would change the oil. If that didn't fix it then I could either "live with it" or be in for a major job to clean out the orifices which would involve dropping out the motor as the area was inaccessible to work on.

So I can't find anything related to such a timing system for this engine in my google searches, I'm seeking input from the forum. I am a small engine mechanic by trade but haven't done an work on car motors for 30 years. There was no such system that advanced valve timing involving oil pressure back then so I'm skeptical. But there have been many advancements of course in engine tuning since.

Any input greatly accepted, before getting a second opinion.

 

[noobytoogy]

The 3.2 engine was designed to go into an East-West engine bay.

In the Touareg it has been turned through 90 degrees but is not North-South with the timing chain at the front of the engine: it's been installed South-North so the timing chain and it's hydraulic tensioner is at the back of the engine up hard against the bulkhead.

Timing chain stretch is a known issue on this engine. Unless you can find a mechanic with very small hands who knows what they are doing, then to replace the chain and tensioner is an engine out job.

However, a number of people have found that if you remove the hydraulic tensioner, which I understand is just about accessible, and re-prime it in a bath of engine oil before refitting it, this may be sufficient to restore the engine to good order.

 

[FSJ Guy]

I have a 3.2 VR6 in an Eos. And yes, they DO adjust both the intake and exhaust valve timing via oil pressure. Crazy, but true. So they're not trying to scam you.

Take it out on the highway and go for a long drive with the Seafoam in it. When safe and able to, mash the skinny pedal. Pretend you're "blowing out" the carburetor passages! LOL!

Your mechanic is correct. That may (hopefully) be enough to dissolve the crud in the oil passages.

This is why it is crucial to do regular oil changes (which as a mechanic I'm sure you do any way) and put the manufacturer's recommended oil in. Some people (not implicated you) don't and then wonder why their engine isn't running right with generic dino oil that is over a year old.

 

[G6mdxvct]

I have a 3.2 VR6 in an Eos. And yes, they DO adjust both the intake and exhaust valve timing via oil pressure. Crazy, but true. So they're not trying to scam you.

Take it out on the highway and go for a long drive with the Seafoam in it. When safe and able to, mash the skinny pedal. Pretend you're "blowing out" the carburetor passages! LOL!

Your mechanic is correct. That may (hopefully) be enough to dissolve the crud in the oil passages.

This is why it is crucial to do regular oil changes (which as a mechanic I'm sure you do any way) and put the manufacturer's recommended oil in. Some people (not implicated you) don't and then wonder why their engine isn't running right with generic dino oil that is over a year old.

Not certain that is completely accurate. The vr6 uses hydraulic timing chain tensioners that work on oil pressure to keep the chain tight. The upper tensioner is easily accessible, however the lower requires pulling the engine to replace. The tensioners are nothin more than small pistons that push against the chain bumper. The tensioners have nothing to do with variable timing.

There are two camshaft adjustment valves on the back of the block that are electronically controlled that vary the camshaft timing as required. Between the adjusters and the ECM the car can run pretty well even if the chain is stretched.

If the timing chain is sufficiently slack you will get a CEL and codes 18, 16, 346. You will also be able to hear the chain rattle.

I would look at plugs and direct ignition coil packs as a potential source of the problem.

 

[G6mdxvct]

The camshafter adjuster valves are electrically actuated solenoids that control variable timing. If they are locked up there us no variable timing adjustment, however have not heard in this condition (locked) causes misfires. No way to replace without pulling engine. The adjusters distribute oil pressure to change direction and travel of adjuster and adjusts the cam angles in relation to crankshaft. If the adjuster is mechanically seized or inadequate oil pressure exists no adjustment. So basically loss of variable timing.

Since the VR6 is direct injection you may have carbon build up on the intake valves. If the build up is severe enough it will cause multiple misfires and prevent the valves from properly seating. A bore scope will reveal this condition. Usually the best way to clean is to blast with walnuts or similar bead blasting. Even with frequent oil changes the build up of emissive gases in the system will build up carbon on the valve (backside & seat).

Somewhere I read you can electrically shock a mechanically frozen camshaft adjuster either on this site or audi forum. It is possible to reach the electrical connectors for the adjusters. Pretty much have to lay on top of engine. The adjusters are lower than the camshaft sensors and center of block.

 

[G6mdxvct]

quick way to check if your timing chain is elongated/stretched is to check measuring block 208 & 209 i believe. If cam reading is not between -8kw & ÷8kw your chain is stretched. A stretched chain should not cause misfires, but will cause lessor performance. Drove mine for over 4 years with a CEL and stretched chain. The cel was camshaft postion and corelation errors. Had chain rattle at start up, worse in winter however once car reached optimum operating temp 200f oil and water no marbles in a can noise center dash. Since I have had gears chains tensioners etc changed there is no chain noise at startup hot or cold.