[Alexander]

Hello all,

Been reading the forums on and off for months trying to narrow down what is wrong with my Jetta. Alas, I'm just going to go out and explain my situation in as clear detail as possible, and hopefully someone can narrow it down.

Symptoms:
- Rough Idle on cold start
- Surging (rough?) acceleration after said cold start:
-> Engine does not hold a constant RPM at lower throttle and constant pressure on the accelerator. (It kind of goes "vroom-vroom-vroom" instead of a nice constant vrooooooom). However, if I accelerator harder, the rpms go up and the surging goes away. After the engine has warmed up, the severity of this goes away, eventually dropping to non-existent.
- Gray/Blue smoke on cold start
- Lots of black smoke when I accelerate hard while driving
- Poor fuel economy
- Oil in the air intake
-> found oil in the crankcase breather hose
-> found oil just before the EGR valve, coming from the intercooler end (I think?)

Things that are ok:
- Intake recently de-coked
- New MAF
- New fuel filter
- New Air Filter
- Power seems 'ok'
- No loose vacuum lines (but I have not done a vacuum/boost leak test)

Possibly of note: My car is parked every day on an inclined driverway.

So, is there an issue with fuel injection system? The Turbo? (please not the turbo!)

Thanks for any advice!

 

[kevapex]

Some oil is normal. It comes from the CCV hoses. Have you tried changing fuel stations and using some diesel purge to clean the injectors? Maybe they aren't spraying well. It doesn't sound like the turbo to me. Do you have any error codes?

 

[Seatman]

The black smoke under acceleration suggests a possible boost leak to me, I think it's because it doesn't get enough air to balance out what the injectors are throwing in and it could well cause the rough running too I would've thought. Here's the faq if you haven't already seen it and there's stuff in there about boost leaks, I think it's in the limp mode faq.

welcometomyturbodies

http://www.myturbodiesel.com/1000q/a4/a4-ALH-TDI-engine-index.htm

 

[chittychittybangbang]

Have you checked all fuses? Here is one case where rough running was fixed by a simple fuse:
http://www.myturbodiesel.com/forum/f5/99-passat-tdi-engine-control-sensors-problem-6317/

 

[Alexander]

I was just driving behind my car on my motorcycle while my girlfriend drove, and I noticed that my Jetta in fact spews out grayish/blue smoke just about anytime the throttle is engaged (but just at first, after a second it goes away). I was wondering if this would help narrow down my issue.

Also, would buying a VCDS cable allow me to diagnose this accurately?

Cheers,

Alex.

 

[chittychittybangbang]

Buying a VCDS cable will help, but like any other tool, you have to use it properly. I would start by checking the fuel injection quantity and timing which is done w/the tool.

It could be old nozzles. Many TDI have a little puff when shifting, especially the 2003 and earlier. Maybe timing?

 

[Alexander]

Some oil is normal. It comes from the CCV hoses. Have you tried changing fuel stations and using some diesel purge to clean the injectors? Maybe they aren't spraying well. It doesn't sound like the turbo to me. Do you have any error codes?

I do not have any error codes, and I did add a bottle of diesel purge to the engine a little while back, it didn't change anything.