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Discussion Starter · #1 ·
I have a 2010 Tiguan Wolfsburg Edition, purchased pre owned from VW with 5k miles on it. At 20k miles the "intake manifold runner assy to be faulty" was replaced. I now have 42k miles and have been experiencing sluggish exceleration and running until the car warms up. I took it in and was diagnosed to have a "cold start misfire on 3 cylinders". Upon examination with a borescope excessive oily carbon build up on intake valves were found. This is hard to swallow considering this car has 42k miles on it and I always use premium fuel. Does this seem normal or acceptable???
 

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yes, it's normal for this engine...and all direct injected engines. The fuel injectors are spraying fuel right into the cylinder instead of on the back of the valves. While this gives much better power and fuel economy, it causes the oil from the breather system to build up on the back of the valves and cause this problem.

Unfortunately it's not covered under warranty and it will run you 500-600 dollars to remove the manifold and clean everything. Performing a direct injection decarbon service every 10-15k miles will prevent this from happening and prevent the manifold from coming off to clean it by hand.
 

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Discussion Starter · #3 ·
Thank you nitroscope8 for responding, I hoped you would. I had the valves cleaned yesterday to the tune of $950 (less a 20% coupon). It does not seem to be sluggish as it was before. However, my MIL came back on after the 30-minute drive home. My Tiguan is back at VW today. What I am really concerned about is how much build up there apparantly was. The service advisor stated that the technician was in aw at the build up, that it was heavy. What would cause this build up that seems to be heavier than normal? Could it have anything to do with the intake manifold runner assy that was replaced at 20k miles? I love my Tiguan and had planned on driving it for a LONG time, but I just can not afford costly repairs. I'm a conservative driver, use premium fuel, and only take it to VW for service...
 

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I was told by a reputable tuner that the brand of oil you use may have a part to play in it as well. Less expensive oils that are not 100% synthetic break down faster and contribute to the deposits. I know you said you get your service at the dealer but maybe a change of oil brands may help. Other choices are oil catch can or water/meth injection, both cheaper than what you paid for that cleaning.
 

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Discussion Starter · #8 ·
When I took my car back to VW for the MIL the computer was reading coldstart misfire again, but there were none logged. They suspected it was residual from prior to cleaning. They took it out for a ~15 mile test drive and really drove it I'm sure. I've had no more problems since.

As to the gas I was using, yes it was premium, from the grocery store fuel center. I'm changing to Shell to see if this helps.

VW has noted the issue on my cars computer files and this is something for us to watch now.

I appreciate input from my fellow VW owners!
 

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Yes, look into "Top Tier" gas stations... the gas really does make a difference in these engines. You can notice the gain in fuel economy from using a "Top Tier" fuel as well.
 

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^^ That is all I use.

I'm sort of wondering what my 2.5 is looking like after 100k miles vs someone else's engine that doesn't use top tier fuels.

Tempted to get a scope to check, however, I'm not sure if it is just easier to remove the intake.
 

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The 2.5 DOES carbon up, however. Mostly around cylinder 4 and 5 which happens to be where the breather inlet is. I did a thermostat on a 2.5 beetle with about 80k on the clock and it had a few mm thick band of carbon around the intake ports. It was very soft and i'm sure a round of seafoam would clean it out pretty good.
 
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Nitro: As a preventative measure against the carbon build-up would you suggest Seafoam or having the dealer take care of it? I've never used Seafom and I dont want to harm the engine.
Thanks.
 

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The dealer should have a BG DIRECT INJECTION cleaning kit AND a standard engine cleaner kit. Have them do the dI kit and it will prevent the buildup if done every 10-15k miles.
 
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Discussion Starter · #15 ·
My Tig is now at 57k miles. Within the past few weeks it stalled on me on two different occasions. Once while in reverse backing out of my driveway (had been driven prior to, was not a cold start) and the second time in a store parking lot. I took it into the dealer today. The intake manifold was replaced under warranty. Was told the warranty had been extended to 120k miles on this part. Service ticket states the following: "Vehicle has fault in system for intake manifold runner position sensor range performance. After diag determined intake manifold is faulty and needs to be replaced. Installed new intake manifold along with new injector seals."

Love my Tiguan, but am concerned about pricey repairs down the road.
 

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oh. a member on another forum chose to replace his intake manifold because the runners were really caked with so much buildup. but he claimed his valves were relatively clean as well.
 

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The intake manifold had a bad design on the flapper port, it would pop out causing a vac leak. The new design is good.

Next up to worry about is the timing chain tensioner and injectors. Carbon will always be an issue.
 
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