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Hi

Just seen a good video from pine hallow auto diagnostics, re a similar problem . Long story short he advised to do a wiggle test of all connectors and looms . Pay special attention to any contact points ie wirring touching other parts .

Worth a go and no cost other than time

Regards

Sent from my SM-A526B using Tapatalk
 

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'Wiggling' on its own always worries me because it's an intermittent fault cause without good feedback as to what's happening. I had a poke around some FSI wiring diagrams (I have the Tdi). I'm not confident I'm looking at the right thing - Intake manifold flap motor? Their picture grapic shows more than a motor which means it could have an angle sensor inside or as they do with other flaps, there's an IR sensor sensing the open and close stops at each extreme allowing the ECU to calibrate the range and pulse it to any position. 2 wires on the connector are probably the d.c motor power? At key on when the flap calibrates it would be taken to one or both ends stalling its motor or being detected by IR intenally. If you can probe and find the motor wire pair activating at key on, then voltage on the wire pair = motor operating. That doesn't tell you what angle the flap is at, but if you monitor with a dvm and start wiggling wires about, any voltage on the flap motor must mean the flap is changing position.

V.W ground tap connections inside the wiring loom are always worth considering and this assembly has one. Once you get some means of detecting when the motor is running, wiggle the wiring harness as well.

I still think ignition, injectors and valves are the main suspects for misfire on a specific cylinder.
 

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I am glad to see this thread is still lively. It took me a while to get back to the items I checked and here it is:

1. Flap actuator: video evidence shows at key "on" position it moves cleanly from homogeneous to stratified and then makes two small motions closer to fully stratified at the end. I assume this is its calibration routine. So this is working normally from what I see even if it takes 2 seconds (more on that later).
2. Cam lobe: inspected all camshaft lobes and there is no obvious signs of wear or difference lobe to lobe. I did some basic measurements and all cam lobes appear to be correct.
3. PCV again: since I had to remove the valve cover I decided to change the PCV to the block-plate type. Voila, problem went away!

I checked the PCV I removed and it is operating perfectly. I could not find any leaks in the tubing or anything and was a little stumped. It is possible that during my inspections something changed, but I am highly suspect of the PCV now. After some thought I may have a possible reasoning.....

Ok, so my engine has 141K miles on it. It is not new. It probably has "more than normal" blowby. That means the PCV system has to work harder than ever to evacuate the pressure. By removing the option of allowing pressure to enter after the throttle body (that is what the block plates do) and only allow blowby into the turbo inlet, I have given the engine an easier path to evacuate crank pressure and eliminated the additional "air" that enters after the TB. I do not understand how the MAF even deals with that! I am sure when the engine was new, the qty of air post-TB (post-MAF) was not a big deal, but now I bet it is, especially when cold. I think that is why the solution worked and why this is so common as engines age, but it could be something even simpler....

My video of the actuator got me thinking.... it takes it a full two seconds to get in position when I put the key on. Normal people just turn the key all the way to crank with no delay. What position is the actuator in at first crank? Currently, I have been delaying between on and crank for 2 seconds to allow the actuator to complete its dance. I did this for over 1000 miles of driving and 200 starts and no code. So maybe, it was getting a code or two every time I didn't delay in the past and they build up until enough throw the light? That seems feasible. Could be something others may want to try.

But as of now, the car runs great when cold and does not throw a code which is all I want. I will see how long that lasts! LOL

RGAZ
 

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The problem with efi is it's a great concept to manage engine wear and maintain performance on the flat of the curve for longer, until the software controlled feedback gets outside limits and the curve reaches the 'cliff edge'. We used to think engine life was 200k plus when parts wore out , oil burned with black smoke and power reduced. Now end of life seems to determined by when the computer can't compensate any more, even though the engine starts and runs?
 

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Swap over plugs\coils\injector from a working cylinder - you should have done that first! If the fault moves you know it's one of those.
Glad you got it sorted in the end, but that advice was in post #2.
 
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