'96 Passat TDI Running Rough

I can't seem to find anyone who can diagnose the problem with my TDI. When the engine is cold it starts right up, but quickly drops in RPM (coughs -almost dies but doesn't). While it is surging (only a couple of times when it isn't too cold out) it is smoking badly. If you try to drive it right away it shugs and sputters and smokes badly, especially at low RPM. If you let it sit warming up for a couple of minutes it runs pretty good, but smokes a lot worse than it used to (even with mild acceleration). After it warms up the idle is rough, but not all the time - it comes and goes. It really isn't too bad, but definately not right. I have gotten some advise, but nothing has solved the problem yet.

I have replaced the following parts:
air filter
fuel filter
vacuum hoses
timing belt
glow plugs and harness
fuel injectors
fuel temperature sensor (inside injector pump)

There is about 145,000 miles on the vehicle, any expert advise would be greatly appreciated!

Thank you.

Is you're fifth injector still working?

Here, kitty, kitty...

The cat injector is downstream of the engine. It is an open loop system (note: B4) with no feed-back to the ECU needed to initiate changes to engine operations. The cat injector operation (or non-operation) has no bearing on this situation.

Have to checked the start of injection timing? Have a VAG-COM scan and check if the temperature and timing coordinates fall within the acceptable window area of the injection start graph. Being far out of this window can cause many of the issues you describe.


to Moderator: Might this receive more and quicker replies if it were moved to the A3-B4 section?

kkberg said:

I can't seem to find anyone who can diagnose the problem with my TDI.

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[Dionne Warwick music] k, do you know the way to Fullerton? [/Dionne Warwick music]

Have you had it on a real-time VW-specific scan tool like VAG-COM so that you can see what's going on here?

Wrong injection timing is quite possible.

Lug_Nut said:

Have to checked the start of injection timing? Have a VAG-COM scan and check if the temperature and timing coordinates fall within the acceptable window area of the injection start graph. Being far out of this window can cause many of the issues you describe.

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GoFaster said:

Have you had it on a real-time VW-specific scan tool like VAG-COM so that you can see what's going on here?

Wrong injection timing is quite possible.

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What if he has a BK ECU?

If I were to advise you with advice, I would also think about pulling your intake manifold pipes and see how clogged your air pathways are. With 145 K and a running EGR, it is probably having breathing problems. Sorry, but not an experts advice, just what I have picked up from my 97 B4.

philh said:

What if he has a BK ECU?

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VAG-COM and BK ECUs communicate just fine. The problem arises when you try to use an OBD2 generic scanner.

Thanks everyone - I am going to get it on a VAG-COM to see if it sheds any light on the problem.

OK, good to know. Learn something every day!

paramedick said:

VAG-COM and BK ECUs communicate just fine. The problem arises when you try to use an OBD2 generic scanner.

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