Slow 1Z: Like a Crutch - Performance Issues?

Hello forum community,

My Golf Mk1 has lost power. I have a G3 95 model with a 1Z engine. The car has extremely poor acceleration. It's sluggish up to 2000 RPM, and then the engine sounds strange, and it only moves forward with a lot of throttle input. If I drive on the highway for a while at around 120 km/h and then try to accelerate, nothing happens or it accelerates very slowly. The same thing happens if I'm driving at 140 km/h for a longer period. With great effort, the car can reach about 170 km/h when given full throttle. I have deactivated the AGR (Exhaust Gas Recirculation), and the boost pressure seems to be okay (checked with an LDA). When accelerating in third gear from 1100 RPM to 4000 RPM, it reaches 0.5 bar of boost at 1500 RPM, and then full boost of 0.9 bar from 1900 RPM. I replaced the MAF sensor with a diode version, but there's no change! The problem is that I don't have a VAG-Com diagnostic tool, and I don't want to go back to the dealership because they don't seem to know anything anyway.

Do you have any suggestions as to what might be causing this?

What is the difference between a quantity control valve and a flow regulator?

reuselkopp wrote:

What is the difference between a quantity gauge and a dosing valve?

The mass airflow sensor regulates the amount of fuel injected, while the injection timing controller regulates the timing of the injection.

Quote:

The problem is I don't have a VAG-Com, and I also don't want to go to the dealership anymore because they don't seem to know anything anyway...

Well, things will be more difficult if you stubbornly resist this very sensible solution (reading the error codes).

m,

What can you do with the unlicensed version of VAG-COM? What is the difference between it and the full version? Can you use it to read error codes?

Yes, it is possible to read the error codes.

And even VW shouldn't be too difficult about it...

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

... Replaced the Lmm with a diode, no change!
Hello,

My assumptions:
- LMM (how much experience does he have?)
- Injection rate adjuster (mileage, kilometers?)

Did you really do everything correctly with the LMM diode (are there any good instructions and pictures from Dieselmartin here )?
There should be a noticeable difference, even with a functioning LMM.

Okay, first things first, you need to read the error codes. You can do this at a dealership or with shareware (there's a lot you can do with it) like VAG-COM; it's up to you.

Could you briefly describe the sound of your engine? (It would be best to read an article about engine noises in emergency mode beforehand!)

Does it produce soot? (Regarding LMM vs. diode).

Best regards, Georg.

Hello,
Okay, so the LMM (likely referring to a Lambda sensor or similar) should have approximately 70,000 km on it. However, ATU recently installed a new one as a test, and it didn't result in any significant improvement in performance. The total mileage is 190 km (for the fuel injector).
Okay, so I mean, I think I connected the diode correctly... but as mentioned before, there was no significant improvement in performance. It maybe ran a little better on gas, but it wasn't really worth mentioning.

My engine is making a weird noise... um, I mean, the sound of the engine is getting rougher, like it's building up pressure... it's kind of a muffled, harsh sound.

It doesn't produce any smoke either, whether using the MAP sensor or the diode.

I suggest that, before we start guessing wildly here, Reuselkopp provides some measurement data, and we can then discuss further based on that information, rather than resorting to speculation. Without these values and without reading the error memory, we won't get anywhere!

@reuselkopp

Please search the technical articles. There's a wonderful article on troubleshooting performance issues. I think that if you follow what's written there, you should be able to solve the problem. Also, performance loss is a common issue. Your specific symptom might not perfectly match what's often described, but it could still be related.
The search for 'performance loss' and '1Z' yields 36 results. Hopefully, something useful can be found among them!

I would suggest that, before we start guessing wildly here, Reuselkopp provides measurement data, and we can then discuss further based on that, so it doesn't degenerate into mere speculation. Without these values and without reading the error memory, nothing will come of it!

Correct!

Sorry, my fault. Speculation mode - OFF.

I just wanted to convey that his engine isn't completely broken, and that the problem can certainly be solved by reading error codes and studying technical articles.

Hey everyone,
Okay, I've done some measurements and ordered an interface to read the data. I looked into your suspicion that it might be related to the fuel injector control valve, as far as my current hardware allows. I checked the fuel injector control valve. There's approximately 16 ohms between pins 2 and 3 (on the pump side). The valve seems to be okay. With the ignition on, there's battery voltage at pin 3 relative to ground in the connector. So far, I think everything is OK! But now...there's also battery voltage between pins 2 and 3 in the connector with the ignition on. As far as I understand from the threads here, there shouldn't be any voltage there. I think I have a short circuit in my control cable for the N108. Furthermore, I tested pin 2 in the connector against the positive terminal of the battery (with the ignition off) and also found battery voltage there. I would say there's a short circuit to ground in the control cable for the N108!
Am I understanding this correctly, or am I making a mistake in my thinking?

Greetings.
Reuselkopp.

PS: Hopefully my cable will arrive this week so I can re-check the control unit.

PIN 2-3 on the pump is **NOT** the fuel injector control.

https://community.dieselschrauber.org/en/viewtopic.php?t=3208

This is the variable coil of the HDK from the manufacturing plant! So it's something completely different!

Since I found this major error at the beginning of your post, I didn't read any further .

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hmm.
I don't understand a lot of things here right now.
Just to make sure we're talking about the same connector, I mean the small 3-pin connector located to the right of the larger 8-pin one. It's the one where the engine shut-off valve is also connected.

Am I completely wrong? Did I measure in the wrong places?
The reference thread I'm referring to here is "Performance loss in G3".

Greetings.
Reuselkopp.

Oops.

I didn't say anything .

Sure, if you have the 3-pole and 8-pin versions, then you are right.

"I diagnosed and towed a Polo SDI on Friday. It has the 10-pin connector and a faulty injection timing valve (25 degrees advance sounds AMAZING!)."

Therefore, I was only thinking about the pump connector. (The N108 is included with the 10-pin version, but it's an extra part for the 8-pin version.)

Okay, now it's clear .

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

@Dieselmartin

What do you mean by "I'm right"? Are you referring to the issue with the plugs, or my assumption about the short circuit?

Greetings.
Reuselkopp.

Hello,
mein Verdacht auf einen Kurzschluß in den Kabeln hat sich nicht bestätigt. Ich hatte gestern Abend nocheinmal alles durchgemessen. Außer ich habe einen kurzen direkt im Steuergerät. Als ich die EDC ausgebaut hatte ist mir lediglich aufgefallen das ein Massekabel (braun) vom LMM und das graue Kabel vom NHG blankgescheuert waren. Ob dort ein Kurzschluß war oder nicht kann ich nicht sagen da alles so voller laub und dreck war das ich nicht sehen konnte ob die blanken stellen an der Karosserie lagen. Beim LMM kabel wäre es ja ohnehin egal gewesen. Was passiert wenn das graue Kabel einen Kurzen hat? Kann dadurch der NHG einen Schaden nehemen? Desweiteren habe ich mal während der Motor im Leerlauf dreht das NHG Kabel abgezogen maber ich hörte keinerlei Veränderungen des Motorgeräuschs. Ist Is that normal?


Greetings.
Reuselkopp.