2000 Jetta TDI loss of power after clutch replacement

[Jack in NB]

About 300 k miles, clutch and flywheel replaced about a month ago and works great.
But it lost probably 15% of power afterward. It won't climb a nearby hill in fifth, as it used to.
There is no sign of overheating or exhaust smoke, and no panel warning lights appear.
Any thoughts on possible causes?

 

[jokila]

Error codes?

 

[IndigoBlueWagon]

Probably a vacuum line or boost hose got knocked loose. And looking for codes would be a good place to start.

 

[KrashDH]

The only line in the vac system I had to remove when I did my clutch a month back was the line to the airbox (which of course I drove around a few days without re-attached because I overlooked it...). It could be that something else got stressed though during the R&R. It could be coincidence too...

 

[jokila]

The only line in the vac system I had to remove when I did my clutch a month back was the line to the airbox (which of course I drove around a few days without re-attached because I overlooked it...). It could be that something else got stressed though during the R&R. It could be coincidence too...

Usually you have to manipulate the engine level to get the tranny installed/removed. If during that process raising or lowering the engine a vacuum line was disconnected then it could cause poor turbo performance but not necessarily affect brake performance. Usually if the actual amount of boost is not within spec of the requested amount an error code will be thrown.

 

[KrashDH]

Usually you have to manipulate the engine level to get the tranny installed/removed. If during that process raising or lowering the engine a vacuum line was disconnected then it could cause poor turbo performance but not necessarily affect brake performance.

Ha, VERY aware of this as I just went through the battle of dropping the tranny out and replacing the clutch. I just don't see what you'd stress on the turbo side of things that would cause anything to pop off. You have to lower the engine it's lowest to clear the tranny mount bolts below the frame, but it's only a couple inches. But there should be plenty of play in all the lines for that, unless when replacing vacuum lines you cut one too short.

There's plenty of scenarios though, anything is possible. It's amazing what can get clipped or messed with if you don't know it's there or by sheer coincidence. But I agree, checking all the connections would be the first goto, then the check valves, then on and on if it isn't solved yet.

 

[Jack in NB]

Thanks, chaps. Will get it checked for error codes.

But I just became aware that the battery was disconnected for a period during the repair. Could this have given the computer a belly-ache?
And somebody suggested that it thought it was time to slow down a bit in its final years!

 

[BobnOH]

No battery silliness with these cars. Always good to disconnect the thing when working on the car, protects the electrics. Might need radio code, maybe some newer ones have "learn" functions, IDK.
Should be no relation of clutch r+r to power issue. Likely broke or disconnected a fatigued vacuum tube or electric wire/connector.

 

[mittzlepick]

Gunk in the hose that was left off made its way to the n75 vac solenoid causing slight restriction but not complete failure?

 

[wonneber]

Maybe with rocking the motor around you cracked a brittle vacuum hose or wire?
I would tee a vacuum gauge into the system and check it's producing at lease 20 inches.
I used a long hose so I could have the guage in the car to glance at it while I was driving.
Also, check the arm on the turbo actuator is moving when you start the engine.

 

[Jack in NB]

It started showing an intermittent "check engine light".

Finally got it in for a computer check - it showed an error code dealing with the turbo waste gate.

The mech said they played with it a bit, and the lost power is back! The power loss with the clutch replacement was a total coincidence.