Increased Fuel Consumption After Timing Belt Replacement

Hello everyone,
I'm new here and don't know my way around very well. Maybe someone has a tip for me before I have to take it to a workshop.
FZD: Lupo 3L, manufactured in 11/99, 82,000 km.
"So far, it has been working perfectly. Fuel consumption was below 3 liters in the summer and around 3.5 liters in the winter. After the timing belt replacement, the fuel consumption has increased and it no longer goes below 4 liters, even with careful driving. I replaced the timing belt without any special tools, and I marked the crankshaft and camshaft positions, which were back in the same position after the timing belt replacement."
-Maximum speed is no longer achieved, or is only achieved when going downhill (on the highway).
- I have the impression that it doesn't pull as well in the lower RPM range. When the turbo kicks in, it does accelerate, but I can't say objectively whether it's as good as it was before.
-During acceleration, there was a brief "jerking" sensation, but it disappeared after replacing the mass airflow sensor.
- No noticeably increased smoke emissions (only visible when accelerating fully in the headlights of the vehicle behind, which I think has always been the case).
- A noticeable "rumbling" sound occurs during slow changes in load, especially when the engine is warm (although I didn't notice it immediately after the cold restart).

Following the suggestions in the forum, I have already checked and/or replaced the following:
- Leak test of the intake manifold, suction pipe, and hoses.
- Visual inspection of cables and connectors.
- AGR valve and intake manifold cleaned (only minor deposits).
- Turbo/EGR valve mechanism.
- LMM (Mass Air Flow sensor), air filter, diesel filter, all replaced.
-I also had the injection timing checked by the workshop, and they said it was okay.

All the measures taken have been ineffective.
I once read the values using VAGCOM, hopefully they are the correct ones.
http://www.sonnenkraft-freising.de/gruppe134.xls
http://www.sonnenkraft-freising.de/gruppe8910.xls
http://www.sonnenkraft-freising.de/gruppe111316.xls

I hope you can help me; thank you in advance.

hello,
The error is most likely due to the change being made without using the specialized tool.
The specialized tool is not only used to lock the crankshaft and camshaft, but also to reposition the camshaft, as the camshaft also drives the PD elements.
The camshaft wheel is adjustable by loosening the three screws on the wheel.
If you replace the ZR without the special tool, the settings will definitely no longer be correct for the following reason:
The engine has a position sensor on the camshaft.
The engine control unit regulates the injection timing based on the position of the camshaft.
However, if the crankshaft is not in the correct position, it will result in incorrect engine operation.
While the position of the camshaft is correct because the engine control unit regulates it based on the crankshaft position sensor, the dowel pin and the new camshaft setting are necessary.
However, the relative position of the crankshaft is, or can be, completely incorrect.
The camshaft wheel is in two parts. The inner part is locked in place by the locking pin, which also houses the position sensor. The outer part can be rotated one tooth to the left or right after loosening the three screws, as the mounting holes are elongated.


Use this special tool to make the adjustment, and it will definitely be okay again (assuming that the incorrect setting hasn't caused any irreversible damage).

The well-known method of marking components is no longer recommended for PD engines!

These links are very helpful.

/viewtopic.php?t=5121

http://www.lupo3lclub.de/forum/viewtopic.php?t=1005


http://pics.m-eit.de/ZRwechsel/ZR8.JPG

PS: I changed the timing belt two days ago, and I even feel like the 3.0L engine is running a little bit better, possibly due to the new adjustment.
greetings

Hello PowerSound3L.
Thank you for your quick response.
"There's still something unclear to me: during the timing belt replacement, I didn't lock the crankshaft and camshaft, but I rotated them to the top dead center (TDC) position and marked both. However, I didn't loosen the three screws on the camshaft sprocket. So, theoretically, nothing should have shifted, right? After everything was put back together, the crankshaft and camshaft were exactly in the same position (as indicated by the markings). After a long search for the cause of the increased fuel consumption, I finally took my 3.0-liter engine to the workshop – just to be safe, I had them measure and possibly adjust the injection timing. They did that and said everything was okay (and I lost a hundred euros in the process). Now that you mention it, I remember something – after the workshop visit, there was a fault code related to the position sensor in the error memory. I cleared it, but it hasn't reappeared since. Did they perhaps mess something up?"
Or did I mess something up, and should I readjust the settings using the special tool?
What do you think about the measurements? Are they okay? It would be great if you could send me the measurements from your 3L engine (which should be perfect) or compare mine to yours.
Thank you very much.

Hello PowerSound3L.
Sorry, I only read your link to the 3LClub page later. Now things are becoming clearer – the "rumbling" might be the sound of the tensioner rollers engaging on the motor, especially when it's warm. I'll get the parts and the repair manual and try it again.
Regarding the LMM (Mass Air Flow sensor): Have you ever noticed that the output signal of the LMM, when measured with an oscilloscope or a fast multimeter with peak voltage recording, briefly jumps to 12V when accelerating? This is not measurable with a standard multimeter. Is this normal? (This was the same with both old and new LMMs).

Thank you very much.

hi,
When using the timing mark method, the camshaft and crankshaft are approximately in the same position, but not perfectly aligned (100%), because, for example, the new timing belt is slightly shorter.
It also doesn't guarantee that the camshaft is perfectly aligned with the crankshaft.
Since the camshaft sensor is attached to the inner part of the camshaft wheel, while the injection timing is controlled by the engine's electronics, the crankshaft position can still be incorrect.
'With simpler gasoline engines, like those in a Golf 2, we used to do that with marking as well. It wasn't as bad then.'
However, in PD engines, the PD elements are driven by the camshaft, and due to the position sensor, the entire system is naturally more sensitive to even slight deviations.
'With the marking method, it's difficult to achieve very precise measurements because even a marker like an Edding has a width of 1 to a few millimeters, and even slight parallax errors can introduce significant inaccuracies.'
'With the special tool, the crankshaft has absolutely no play, and the camshaft has almost no clearance with the dowel pin; maybe only about 1/10 of a millimeter.'
It's really important that everything is properly adjusted. It's just as important as the ignition timing in a gasoline engine.
When the workshop checks the injection timing, the measured values are taken from the diagnostic system. However, since the injection timing is measured and controlled by the camshaft position sensor, the injection timing is correct as long as the sensor is functioning properly. Nevertheless, the crankshaft could still be in the wrong position.

Your measurements look normal, with no abnormalities.
The second cylinder seems to be producing slightly less power, which is noticeable in the idle stabilization values (1. -0.4, 2. +0.7, 3. -0.4). However, this is still within the normal range (threshold 3.3).

I haven't looked at the LMM signal on my device, but I think the jump is probably normal. I should investigate it more closely.
greetings

Hi!

@evasop:
Perhaps this discussion will help you identify a (potentially!) misaligned camshaft.
[url]/viewtopic.php?t=4893&highlight=synchronisation angle pd[/url]

And for us, it would also be interesting to know if our assumptions were correct back then. So, feedback would be great!

Dirk.

hello,
Measurement block 15, field 3.
That includes the consumption per hour.
Take a look at this.
at my place:
Shift lever in neutral (N), engine fully warmed up (81°C water temperature), all consumers turned off (including ventilation), outside temperature 0°C.
Idling: 0.4 liters/hour (occasionally jumps to 0.5 liters/hour).
2000 UPM: 0.6 liters per hour.
3000 RPM: 2.4 liters per hour.
greetings

hi

@PowerSound
Thank you for the information. Here are my values for comparison:
idle speed: 0.4 liters per hour =
2000 upm: 0.6 l/h =
3000 RPM: 1.9 liters per hour -0.5
What does a difference of -0.5 mean at 3000 RPM?

@everyone
I will be adjusting the ZR (likely referring to a zero-point reset or similar) using the appropriate tools according to the repair manual in the next few days. I will let you know if it makes a difference.

Best regards and many thanks for your support.

Hooray, it's running (almost) smoothly again.
I adjusted the timing chain again using the special tool. There was a significant gap that prevented the locating pin from fully engaging. The fuel consumption seems to be back to normal now.
I still have a minor issue – a rumbling, clattering sound that's particularly noticeable during slow changes in load – but it might be vehicle-specific. I'll probably bring it up on the 3lclub forum. Or does anyone have any ideas?
Thank you very much to the forum and especially to those who helped me with their advice.

I'm not marking the position of the gear relative to the motor, but rather the gear and the timing belt itself. I do this twice for each gear, then I count the teeth between the markings, and I do the same thing with the new belt. I've done this several times on PD-TDIs before, and I've never had any problems.

Best regards,

Hannes.

Hannes wrote:

I have already done this several times with PD-TDIs, and there have never been any problems.

I know workshops that have done it that way before... and in half of those cases, the customers were left with a misaligned timing belt. It wasn't until they re-aligned the timing belt using the crankshaft stop and alignment pin that they realized the new timing belt was off by about half a tooth.

Have fun counting the teeth .

hi,
So, a workshop or someone who does it regularly.
He should have spent the 80 euros and bought the tools.
greetings

Bertil wrote:

Hannes wrote: I have already done this several times with PD-TDIs, and there have never been any problems. I know workshops that have done it that way before... and in half of those cases, the customers ended up with misaligned timing. It wasn't until they re-aligned the timing belt using the crankshaft stop and alignment pin that they realized the new timing belt was off by about half a tooth. Have fun counting the teeth

.

However, with this method, you essentially revert to the original settings, as intended by the manufacturer. I can't imagine that this method actually causes such a significant loss of performance, because over time, the new belt will stretch again, and then the settings will no longer be correct.

Best regards,

Hannes.

evasop wrote:

Hooray, it's running (almost) smoothly again. I adjusted the timing chain again using the special tool.

There was a significant gap that prevented the locating pin from fully inserting. The fuel consumption seems to be back to normal now. }
Hi,

Next time, perhaps check the ZR setting using this method:
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.
This saves you the potential costs / rental fees, etc. for the specialized tool }.
...and, in my opinion, requires the least amount of work.

Hello,

I just read this thread, and I have to agree with what's being said.
Two weeks ago, I took my Golf 4 TDI with a 115HP AJM engine to ATU for a major service. This included a timing belt replacement, two new tires, an air conditioning service, and a brake fluid change.
Davon abgesehen, dass ich nur ärger mit dem Verein hatte (haben mir den Kotflügel verkratzt weil Sie keine Kotflügeldecke etc darüber gelegt haben). Das haben Sie dann aber behoben als ich es gesehen habe. Bin hingefahren und habe mich beschwert. Wurde poliert und ok. (Trotzdem darf sowas nicht passieren) Dann war als noch ein Klappern (das haben se natürlich nicht gefunden) Habe ich dann selber gefunden. Die haben beim Wiedereinbau der ganzen Schläuche etc. die Rohre der Servolenkung weggedrückt udn die haben dann unter dem Wasserausgleichsbehälter an die Karosse geschlagen. Aber wie gesagt, dass habe ich dann slebst gefunden. Aber mein eigentliches Problem ist, ich hatte von Anfang an das Gefühl das er weniger Leitung hatte. Gestern war ich auf der Autobahn und habe mit hängen und würgen 190 auf der geraden geschaft. Also er geht jetzt deutlich schlechter als vorher. (ca. 210) mit einer DTE Box. Außerdem ist der Verbrauch auch gestiegen. Beim normalen Fahren merkt man es weniger das er schlechter läuft, nicht mehr ganz so spritzig aber am Verbrauch fällt es dann auf. Weil ich jetzt hier gelesen habe, das das an den Einstellungen des Verstellbaren NW Rades liegen kann bin ich hellhörig geworden. Wäre ja fast möglich das ATU kein spezialwerkzeug benutzt hat? Muss auf jeden Fall morgen noch mal hin. Hat jemand ähnliches erlebt, oder könnte es auch was anderes sein. Es ist mir halt sofort nach dem Wechsel aufgefallen, war aber wie gesagt erst nicht so extrem aufgefallen. AOn the Autobahn, the difference in maximum speed was quite extreme.

Greetings.
Dirk.

Special tools aside, even though it's simple, you need to be able to use them. You'll inevitably need to check the valve timing, so read here about how to do it; it's "relatively" simple and provides useful information.