Engine Performance Loss: Causes & Solutions

Hello everyone.

Sooooo,

hab mir jetzt die Finger wund gesucht. Who can help me?
My car only delivers full power when the engine is cold. What could be the reason for this?
As soon as the water temperature gauge reaches the middle mark, the engine starts to experience fluctuations in power. This means it sometimes runs normally, and sometimes it doesn't. Between 2000 and 4000 RPM, it doesn't accelerate smoothly and usually only reaches 4300 RPM. Occasionally, I can even rev it up to the redline.
When it's cold, it runs as I think it's supposed to.
Engine: AFN, 110 horsepower, 70,000 km.
Does anyone have any advice or has anyone experienced something similar?
The error memory is OK.
I only know that the injection start deviates upwards from the diagram.

Hello...

Have you already used the search function? There are many possible causes...
You can't say for sure just by guessing. Do you have VAG-COM? If so, perform a diagnostic test and check the mass airflow sensor (MAF).

Best regards, Mike.





Hello everyone.

Sooooo,

hab mir jetzt die Finger wund gesucht. Who can help me?
My car only delivers full power when the engine is cold. What could be the reason for this?
As soon as the water temperature gauge reaches the middle mark, the engine starts to experience fluctuations in power. This means it sometimes runs normally, and sometimes it doesn't. Between 2000 and 4000 RPM, it doesn't accelerate smoothly and usually only reaches 4300 RPM. Occasionally, I can even rev it up to the redline.
When it's cold, it runs as I think it's supposed to.
Engine: AFN, 110 horsepower, 70,000 km.
Does anyone have any advice or has anyone experienced something similar?
The error memory is OK.
I only know that the injection start deviates upwards from the diagram.

Hello,

What reading do you get in the corresponding measurement block for the engine temperature when it's warm?
Error codes? Perhaps the engine control unit indicates that the engine is overheating because the temperature sensor is defective...

Best regards, Rainer.

Golfmann wrote:

As soon as the water temperature gauge reaches the middle mark, the engine starts to experience fluctuations in power. This means it sometimes runs normally, and sometimes it doesn't. Between 2000 and 4000 RPM, it doesn't accelerate smoothly and usually only reaches 4300 RPM. Occasionally, I can even rev it up to the redline. When it's cold, it runs as I think it's supposed to. Engine is AFN, 110 horsepower, 70,000 km

.
Hi.

That sounds familiar, from my time with the original, smaller charger.
However, my charger sometimes also got stuck in the cold.

In any case, I can offer the suggestion that performing an LDA (Linear Discriminant Analysis) would provide clarity as to whether the issue lies with the loader (or its peripherals) or not .

Sure.
That's a lot of different tips.

@mhernach.
The translation of the text I'm looking for is in my first sentence.
I also suspect the LMM (lambda sensor). It now has 220,000 km on it. Is that the one from my old 1Z engine? The values for that were around 800 as the highest. That seems a bit low. I've heard from others in this forum about values exceeding 1000.

@ Rainer K.
So, the temperature sensor? I hadn't even thought of that. I'll check that right away.

@ulf.
LDA hab ich und der Lader hat 10000km gelaufen. Der Ladedruck ist in Ordnung. Weiß nur halt nicht ob es vielleicht an der kleinen Laderdose liegt. Let's see.

@all
I also suspect the catalytic converter. It probably has over 200,000 kilometers on it. Maybe something will change when it gets warm.

Golfmann wrote:

I have the LDA, and the turbocharger has been driven for 10,000 km. The boost pressure is fine. I'm just not sure if it might be related to the small turbocharger unit. I'll take a look.

You don't need: if the boost pressure is the same when the engine is cold and warm, the problem must be somewhere else .

What do you mean by 'cold and warm being the same'?

If I start my Galaxy early in the morning, it takes about 5 minutes for the charging pressure to reach the target value.

Should the boost pressure always reach the target value from the beginning, even when the engine is cold?

Best regards,
Mike


I have the LDA, and the turbocharger has been driven for 10,000 km. The boost pressure is fine. I'm just not sure if it might be related to the small turbocharger unit. I'll take a look.
You don't need: if the boost pressure is the same when the engine is cold and warm, the problem must be somewhere else

mhernach wrote:

What do you mean by cold and warm being the same ??? If I start my Galaxy in the morning, it takes about 5 minutes for the turbo pressure to reach the target value...

Hi,

"What I meant is that, as far as I know, the pressure regulation system doesn't differentiate between a cold and a warm engine; that is, the target pressure set by the engine control unit should be the same (for the same load and engine speed)."

It is normal for the loader to be more difficult to start when the oil in the bearings is very cold, and that it may not quite reach the full pressure under partial load compared to when the engine is warm.

With a sufficiently high load, around 2000 rpm, the pressure should ideally be the same when the engine is cold and warm, with the cold pressure being minimally later than the warm pressure.
I won't try that on my tractor, though, because, in my opinion, that already falls under "cold starting" .

However, concerning Golfman's problem, this would mean that his engine might have less boost pressure when warm compared to when cold – something he has already ruled out thanks to the LDA (Lambda-regulated catalytic converter).

Hello Ralf,

Have you looked into this matter yet?

Quote:

I only know that the injection start, as indicated in the diagram, deviates upwards.

"On my AFN, the injection timing was approximately 140 (displayed in field 2)."
I recently changed it to 38 by adjusting the fuel injection pump.
Since then, the engine has started spontaneously, the fuel consumption has decreased slightly, but...
Best: Consistent power delivery, as expected based on the torque curve.
Previously, there were occasional power interruptions; sometimes it would work, and sometimes it wouldn't.
I've tried a few things - LMM, etc. - but without success.

If the injection timing on your engine isn't "correct," it's definitely a problem.
Good opportunity for improvement.

Best regards,
Ralph.

Aha.

I'm absolutely certain that it's different. I've checked it multiple times already.
If that was the case for you, then I'm quite optimistic that it might be the reason for the same issue I'm experiencing.
Because I sometimes experience starting problems and a lack of smooth running, and I've now discovered that the fuel consumption is around 7 liters! And that just can't be right.

It sounds exactly like what you're doing.
I'm just not confident enough to adjust the fuel pump myself. What all could I do wrong? It could even happen that I can't start the engine anymore.
If the value deviates upwards, I need to turn the pump towards the motor, right?
Lots of questions! Well, anyone who wants to can give me some tips. By the way, I'm familiar with the technical article.
He's good, but I don't know which way I need to turn it.

PS: After the ZR change, the pump was adjusted at VW. By whom else? Everyone else can do it better than VW!

Hello Ralf,

From the perspective of the timing belt side, or, in the case of a Golf, from the right fender.
Rotate the injection pump clockwise (so that its upper part faces away from the engine).
(turned towards the radiator).
To go from approximately 140 to 38 (in display field 2), I estimate I need to rotate it about 10 degrees.
must.
Since this corresponds to a rotation in the direction of the timing belt, I would conclude that...
that I adjusted the injection pump to a later timing. (Please confirm.)
or correction by the professionals here ).
Is there a translation of "Value in display field 2" available in this forum?
°v.OT/°n.OT ?

My first ESP system was completely replaced by VAG (Volkswagen Group) after a timing belt change, including a new...
Timing belt replacement performed by a Bosch service center. Both vehicles should have had...
According to my understanding, the ESP must be correctly configured...
It's definitely an expensive pleasure.

Best regards,
Ralph.

Hello,

I did this on my Audi. Regarding the timing, it's advanced. It's quite fiddly on the A4, but it was done without having to disassemble too much.
@Ralph: That's correct - Impeller facing against the direction of flow = Early.

However, I had 'gaps' because the ESP was located outside the lower, or later, end of the adjustment graph in the VAG-Com software.
(VAG-Com statement: too retarded)
Statement from the VAG workshop: 'It's okay, don't worry.'

My fuel injection system's idle setting was always around 50%.

I intentionally adjusted it to the earlier end, and now it's okay.

Idle speed: Adjust the fuel injector pulse width to approximately 10-15%.

BUT:

I don't believe that adjustments to early tolerance settings cause performance issues.
The ESP may, in the worst-case scenario, be unable to sufficiently retard the injection timing at idle and at very low power levels. Would this even be noticeable?

And: Power loss with a warm engine = warm fuel?

What is the fuel temperature sensor reporting? If the fuel density/temperature compensation is no longer working, it should lose power as the temperature increases. Have you checked that?


What I would also be interested in knowing is:

Can we assume that the injection timing has shifted due to the aging fuel injectors, or was it misadjusted from the beginning after the last fuel injector replacement?

Okay, so my fuel temperature is around 140 degrees. And the injection timing is over 70.
It can't be due to wear on the timing belt; it's only been driven for just under 10,000 kilometers.
I'm going to work on my ESP project this weekend. Hopefully, it will go well. Does anyone have any useful tips that I should definitely keep in mind?
Volkswagen Golf 3 AFN.

@Golfmann:

There are basically two methods to change one's fundamental attitude:

1. Rotate the pump housing relative to the mounting flange.
2. Twist the injection pump rotor on the pump shaft.

1. :
If you rotate the pump, you need to loosen all the fuel lines at the pump and at the injectors to prevent them from becoming strained!
Early timing = rotate the pump counter-clockwise (away from the engine).

2.:
If you rotate the impeller on the shaft, you will need 3 new mounting screws because they are expansion screws!
The fuel injection lines can remain untouched.
Tighten the screws with 20 Nm initially, then check the setting using VAG-COM and, if necessary, adjust it again. Once the setting is correct, tighten them again by an additional 90 degrees.
Early engagement = rotate the pump shaft towards the motor (counter-clockwise).

Good luck!

Regards,
Alex.

Hi Alex,

Could it be that you are mistaken about the direction of rotation?
"On my AFN engine, rotating the fuel pump counter-clockwise (as viewed from the front of the engine) causes..."
Delayed adjustment, and it's also likely that the pump shaft is twisting towards the motor.
(counter-clockwise) can also cause a late adjustment.
I haven't tried the latter yet because I haven't been able to obtain any stretch bolts.
"Turning the pump approximately 10 degrees clockwise, away from the engine," definitely achieves the desired result.
A change in display field 2, from approximately 140 to 38, indicating a later time.
(Always viewed from the impeller side).

@Ralf
Das Lösen der Pumpe und Einspritzleitungen ist unkompliziert. I'm sorry, but the provided text is incomplete. Please provide the full text so I can translate it accurately.
While the built-in motor slightly obstructs access to the wiring, it's still possible to reach them.
Initially, I was looking for the third screw head on the pump impeller side.
...but I eventually found it on the pump side. (I was working in dim light...)
That was the only cliff.

Best regards,
Ralph.

Golfmann wrote:

So, my fuel temperature is around 140 degrees. Golf 3 AFN.

Sure, here's the translation:

"Excuse me?"