Common TDI Issues (PLEASE MAKE STICKY)

[catlin_cava]

Ok so here is some common issues with MK4 TDIs that your going to run into, and How to fix the issues. Ill start with motor stuff, Having a VAG COM is the best for doing most of this stuff.

My TDI is slow and feels like its got no power, But it is Boosting:

-Your Intake is most likely clogged, anything with over 250K (kms) will have some carbon build up and greatly reduce power. Pull the intake off and clean it with a torch and an Air Compressor and your golden with it.


My TDI Keeps going into limp mode when hard accelating, and I'm getting a CEL or a Code 17958.
-It could be 2 issues. First Try switching your N75 Valve with your EGR Valve, if your N75 is going bad and you switch those it will fix the issue.
 or take the vacuum line coming from your Actulator and put a vaccum gun to it and see if it holds, if it doesn't hold your actulator is done.

My TDI has no power on take off and feels like its not boosting then it boost out of nowhere
-your Actulator is done, replace it.

My TDI makes a shuttering noise at an Idle(and possibly changes when the clutch is pressed and depressed)
-your DMF is acting up, swap it out with a SMF and a VR6 Clutch Disk

My TDI is hard to start when cold,
-take a Vag Com and check your IQ on your pump, if the Value is too high not enough fuel is going in, Gives you a hard start but good fuel efficiency. Use the Hammer mod to fix it, Ideal Value should be 3.5 to 5.

My Turbo doesnt feel like its boosting or my TDI goes into Limp Mode, Ive changed the N75 and my Actulator is good.
- I hate to say it but your Turbo may be pooched, you can clean the Vanes inside and it might fix the issue. I suggested getting a shop to clean the vanes can be a headache.



I hope this helps out most of you.

[745 turbogreasel]

My TDI makes a shuttering noise at an Idle(and possibly changes when the clutch is pressed and depressed)
-your DMF is acting up, swap it out with a SMF and a VR6 Clutch Disk

The serpentine tensioner can get pretty loud too

[catlin_cava]

My TDI makes a shuttering noise at an Idle(and possibly changes when the clutch is pressed and depressed)
-your DMF is acting up, swap it out with a SMF and a VR6 Clutch Disk

The serpentine tensioner can get pretty loud too

Yup it can, but i listed if the sound possibly changes it's your DMF, a shuttering DMF isn't hard to miss

[8v-of-fury]

Guillaumes t-belt roller went and it had a shutter deal going on remember?

[Powered by Spearco]

How about the flashing glow plug light that can mean that brake light bulbs are burnt out.

[catlin_cava]

How about the flashing glow plug light that can mean that brake light bulbs are burnt out.

must be a US thing,

Flashing GP light will the car is running usually means a fueling issue,

[GTiTDi]

 The flashing glowplug light can mean much more than a fueling issue, often times it is a result of a failed or misadjusted brake light switch, glow plug circuit issues, etc.

[745 turbogreasel]

Does this connect with #4 bad glow plug code...when that plug is fine
BECAUSE OBD #s the glow plugs in reverse???  02 ALH

A friend of mine tells me she's only had one issue in like 5 years...sometimes when boosting up a hill, it loses power until she removes and replaces the fuel cap.  Clever girl, but what's the real solution?

[theman53]

http://forums.tdiclub.com/showthread.php?t=310218&highlight=smf+clutch

http://forums.tdiclub.com/showthread.php?t=340137&page=2

Best threads I found explaining what clutch setup to use for the SMF in TDI.

http://www.jimellisaudiparts.com/showAssembly.aspx?ukey_product=5448339&ukey_assembly=751739

[smutts]

Vibrating belt tensioner pulley, usually a seized (siezed?) freewheel pulley on the alternator.
But when I sorted my knackered freewheel pulley, I was disappointed that there was more flapping of the tensioner than I would like.

When the idler pulley fell (melted!) off a few months later... "rattle clunk tinkle" bye bye power steering, hello hedge! Once replaced, the tensioner was dead steady. So tensioner vibration can also be due to a dying idler pully.