Power Loss After Timing Belt/ Waterpump Replacement

[gsmith41]

I have done some searching but have not found anything specific to the MK7 platform. Water pump and timing belt were recently replaced by local dealer. I have noticed a loss in power, specifically at highway speed when passing. No check engine lights or other indications that there is something wrong. Is it possible that the timing is not correct? If so, wouldn't this trigger a CEL? Aside from performance, car seems to run perfectly.

 

[Mike_04GolfTDI]

From pictures I've looked at online, it seems that there is room for adjustment of the cam sprocket. There are three bolts that go through slotted holes to hold the cam sprocket onto the cam hub underneath, making it possible to advance or retard the cam timing in relation to the crankshaft.

On older TDI engines, that adjustment was used to adjust the "torsion" value measured in degrees. You check the setting with VCDS or a similar scan tool. I'm thinking specifically of the Pumpe Duse TDI (BEW) engine. Having that setting too far off would indeed cause low power problems on that engine. It's all well documented and plenty of people here have lots of experience with adjusting that.

For the Mk7 cars, with the EA288 TDI engine, I haven't seen a whole lot of information about it. I don't know where you would find a similar "torsion" value in VCDS, but I suspect there must be one.

If you're noticing a lack of power at higher RPM right after a timing belt change, I strongly suspect the cam timing is a bit off. Finding a way to check that, and adjusting it if necessary, would be my first plan of attack for this problem. My wife's car is a Mk7 TDI and at some point I'll be doing a timing belt job on it, so I'm interested in this.... Maybe in the next couple days I'll hook up my VCDS and see if I can find anything that looks like the cam timing.

 

[Mike_04GolfTDI]

Now I'm starting to second-guess whether the pictures I've been looking at are actually for the US Mk7 TDI engine. This would be engine code CRUA. While searching for pictures of "CRUA timing belt" or "Mk7 TDI timing belt" many of the results are obviously not from that engine, and some might be from it or similar engines.

So I'm not completely certain whether the cam timing adjustment exists or not. I would tend to think it must, because how are you supposed to tension the belt while the cam and crank are locked? Something has to turn, and usually that is the cam sprocket (but not the hub underneath which it bolts to).

If someone has a picture of the cam sprocket and/or timing belt area of a US spec CRUA TDI engine then we could tell if the cam timing is adjustable or not. At some point I'll have to take the timing belt cover off my wife's car and have a look. It's five years old now, so time to start thinking about a timing belt change, even though it hasn't reached the specified mileage.

 

[bigb]

Page 7 of the linked EA288 pdf shows one screw with a slotted hole.https://pics2.tdiclub.com//data/517/820433_EA288.pdf

 

[Mike_04GolfTDI]

Okay, so I found something useful.

This link should start the video at 18:17 where he describes the adjustment mechanism for the cam sprocket.

It's different from the three bolt system that I've seen on older TDI's, but it accomplishes the same thing. I assume the reason they did this is because it uses about two pounds less metal. Cost savings, weight savings, or whatever....

I'm totally into looking this stuff up because I know I'm going to have to do it one day.

 

[Mike_04GolfTDI]

Any luck getting your low power problem figured out?

 

[gsmith41]

No, top end power still seems to be down. Is there any way to validate timing with either a VCDS or OBD Eleven?

 

[Mike_04GolfTDI]

No, top end power still seems to be down. Is there any way to validate timing with either a VCDS or OBD Eleven?

I did some googling and found this:

I'm thinking maybe the "Phase Position" value is comparable to the "KW" Torsion reading in the older TDIs. (KW = KurbelWinkel or Crank-Angle...in relation to the cam).

Lacking any definite information, the approach I would take is start viewing any values in VCDS that seem like they'd have anything to do with the cam position. Specifically, I would look for values that seem to be small, and don't change very much with engine RPM changes. Then I would start making adjustments to the cam position and see if anything changes in a way that makes sense. For example, advance the cam, and the number goes up, retard the cam and the number goes down.

If it's anything like the adjustment on a BEW engine, a very small adjustment makes a huge difference. The range that the computer can read is something like -5 to +5 degrees (not exact, but you get the idea) and anything outside that range shows as 0.0. So a zero reading means you're either WAY off, or perfect. So to be sure, you would have to make a tiny adjustment, see what happens, and then adjust it back to zero.

Of course, the typical values you'd see on the newer EA288 engine might be completely different. Once you've identified the correct value that you need to look at with VCDS, it would almost be worth checking it on another car that is running well, to see what is considered normal. If yours is much different, then you could try adjusting until you reach that value and see if it runs better.

Keep in mind, you can destroy your engine if you make a mistake in adjusting the cam, so don't go messing with this unless you are pretty sure you know what you're doing. On this engine I don't know how much adjustment range there is, but if it allows you to adjust it far enough that valves hit pistons, then you could accidentally ruin your engine. TINY adjustments would be the way to go here, and if you had any uncertainty, you'd want to rotate the engine manually a couple of times to make sure nothing is binding up.

I've made this adjustment probably fifty times on a BEW engine, but never on a newer one, so feel free to seek professional advice. I could be wrong about everything!

 

[pedroYUL]

I changed the timing belt (myself) on my wife's GSW and honestly I didn't have to adjust anything, no torsion value, nothing.

Remember, the CVCA and CRUA both have variable valve timing, which will adjust for small differences in "torsion values".

How long ago since you changed the fuel filter?