1.9 TDI: Intermittent Engine Misfire - Causes & Fixes

Hello everyone,

I'm having the following problem: My 1.9 TDI (1Z 1994) occasionally hesitates or stalls when I try to accelerate.

that means the following:
- I press the accelerator (whether quickly or slowly, a little or a lot), but it doesn't respond. I can even press it all the way down, and it does nothing. There are no error codes in the engine control unit, and the live data shows that the throttle body is working perfectly (it shows 100% even when I'm pressing the accelerator fully), but the engine still doesn't respond.
- So far, so good. However, if I let off the gas and then press it again, it works without any problems. It responds to the gas pedal, and everything functions perfectly (excellent performance, the RPM is normal, and there are no noticeable issues).

I'm calling this "lupfen" because I'm giving it gas, then releasing it, then giving it gas again, and it responds.

Just a heads-up: the engine is from a 1994 Golf 3 1.9 TDI, but it's now installed in a 1989 VW Type 2 T3.

I have no errors whatsoever. When it was still in Golf configuration, I had no problems either. Now that the conversion is mostly complete, it starts without any issues, no jerking or misfiring, or anything like that. It runs perfectly, except that it doesn't always respond immediately when I press the accelerator.

There's also no noticeable loss of power, although it's hard to judge that in a bus, since it previously had 50 horsepower (1.6D CS) and now has 90 horsepower, with double the torque. (But you can definitely feel the power when it accelerates).

"All the vacuum lines are connected, the LLK pipes and turbo are all present and working. I'm at a loss now and I've already searched here in the forum and everywhere else. (My eyes are square from looking so much!) But I haven't found anything, or I don't really know what I'm supposed to be looking for."

As I said:
- No errors found in the control unit.
- No anomalies detected in the VAG-COM readings (as far as I can see).
- Occasionally fails to ignite.

I hope someone can help me.

Thank you in advance.

best regards

alex

Currently, the following error has occurred:

Intermittent issue with intake manifold pressure regulation differential.

Unfortunately, I deleted the error code before I saved it, so I can't provide you with a specific error code. I then used the search function to look for that error.

Okay, try to investigate the wastegate tomorrow, and if necessary, make it functional. Afterwards, check all the vacuum and charge air hoses again (even though I've already checked them at least 5-6 times), and if that doesn't help, you'll have to help me .

Best regards,

Okay, so it seems like the LLK hose wasn't fully connected. That probably caused the intake manifold pressure regulation error. The error is no longer appearing now.

However, the issue with the gas intake remains. I also checked the charging pressure. What is the correct charging pressure for a 1.9 TDI? Is it 0.7 or 0.9? I'm not entirely sure. Anyway, it was behaving like that.

I then removed the boost pressure control valve to see if the problem was related to the gas. No, it wasn't. However, the boost pressure increased up to 1.1 bar, and then I .

I'm actually completely stuck now. The VW master technician, of course, wants to install a new turbocharger for me (what else would I have expected?), although I believe mine is fully functional.

I am grateful for any advice.

By the way, I've noticed a rather loud hissing sound when I release the accelerator, which seems unusually loud to me (like a very loud "tuning blow-off valve").

Best regards,

And how did the story end?
I'm experiencing a similar problem with my Golf 3 when it stalls.

Hi,

Okay, I fixed the problem. It turned out that the Golf has two brake switches, while the bus only has one. This caused the ESP system to receive incorrect signals and inject fuel incorrectly, etc.

It's possible that your switches are "misaligned." I seem to remember there being an adjustment thread, as the switches need to operate quite synchronously. You should probably check that sometime.

Please provide the German text you would like me to translate into English.
Here's a quick guide for everyone who's converting their car to a TDI engine:

Okay, in golf, there are the following switches:

F47 opener disconnects the ground connection from T68/20 (0.5mm², white/yellow).


"The normally closed contact (F) connects terminal 30 (which is always energized)."
- the brake lights
- and to the circuit breaker panel E/3 with red/black 1.0mm² wire.

From the fuse box, connect with 1.0 mm² wire (black/red) to TV11 (distribution terminal for terminal 54, located above the relay panel).
From TV11, continue with 0.5mm² black/red wire to T68/44 (control unit).

If you currently have two switches (one normally open, one normally closed), you simply need to connect them in that configuration.

So:

Schließer:
Terminal 30 (constant positive).
|
|
|
./
|
|
|
o T68/44 (sw/ro 0.5mm²)
Bitte gib mir den deutschen Text, den du übersetzt haben möchtest.
Opener:
o T68/20 (ws/ge 0.5mm²)
|
|
|_
./
|
|
|
o Mass
Bitte gib mir den deutschen Text, den du übersetzt haben möchtest.
T68 = Control unit.



Best regards,

Hello JamDaf,

Is the problem completely resolved now?

I used to own a Golf 3 with a 1Z TDI engine (also manufactured in 1994). I bought the car with 70,000 kilometers on the odometer and sold it with 270,000 kilometers.

From the very beginning, there has been the problem you described.
It happens sporadically, mainly after longer drives at a constant speed, that when I press the accelerator, there is no acceleration. There's a brief 'stutter,' and then it starts moving forward again.

Until the very end, no one could explain it to me. I just had to get used to it .

It would be quite funny if it was just a glitch in the switch .


Best regards,

Yes, it's completely gone. I only found out after about 6 months... so I had already gotten used to it (I drove about 15,000 km with it). The TÜV (technical inspection) wasn't happy about it, but I was allowed to accelerate during the emissions and noise tests (since it was a special inspection).

Best regards,

Thank you for your tip!

The switches are working fine on my car. Otherwise, the cruise control wouldn't function either.

I think I've figured out how to replace the N75 boost pressure regulator.
I had another one that had been cleaned, and the suction and blowing test revealed a noticeable difference.
In any case, the problem has not reappeared under the same circumstances.