Engine Misfires on Cold Start - ARL Diagnosis

Hi everyone,

I'm writing back after a long time .

Okay, so...

'Approximately 7,000 km ago, the timing belt broke (88,500 km), and as a result, a completely new engine was installed. At first, I noticed that the engine would sporadically shake/jolt during cold starts in the morning, but I didn't think much of it . Last week, I experienced a brief engine cut-out on the highway while driving at full throttle, but no warning lights illuminated. Additionally, the ARL TDI is no longer reaching its maximum speed; on flat ground, it only reaches about 200-205 km/h, and it doesn't really want to go faster even downhill.'

I went to the mechanic today because of the speed problem and the jerking, but he couldn't find anything wrong; the error memory was empty!

Does anyone have any idea what this could be? Oh, and it's a model year 2/01.

Thank you very much.

Christian.

Hello, I'm not entirely sure if your engine still has the G28 sensor (speed sensor).
If so, I would start looking in that direction.

Hi,

How else does the crankshaft position sensor manifest itself? Also, does it cause a loss of power?

My performance curve looks something like this -> http://people.freenet.de/BW-Bilder/Leistungsdiagramm.jpg

Regards,

Christian.

Chris wrote:

How else does the crankshaft position sensor manifest itself? Also, is there a loss of power?

Hi Christian,

When the speed sensor fails, the engine is supposedly shut down .

I don't know when occasional, potentially temporary, interruptions of the sensor's output will be interpreted as a failure. In any case, the Electronic Drift Corrector (EDC) is likely to become quite confused, which should be noticeable through interruptions, jerks, and erratic behavior.

Given such significant errors, I (as a programmer) would set the tolerance threshold for error reporting very low.
If the tolerance threshold is set higher, it is quite possible that occasional errors will not be recorded.

Or could the workshop possibly have suppressed an error entry ?

Hi Ulf,

The error code wasn't cleared, and I checked the diagnostic memory myself using VAG Com beforehand... I don't trust those guys at VW anymore.

What do you think of the performance curve? This plateau above 2000 RPM is quite peculiar, isn't it?

Regards,

Christian.

Chris wrote:

What do you think of the performance curve? This plateau above 2000 RPM is quite peculiar, isn't it?

Hi Christian,

die Ebene "berechnet" sich ganz einfach aus dem steilen Drehmomenteinbruch in dem betr. Speed range.

Overall, it seems most likely that this is caused by excessive boost pressure followed by a subsequent correction, possibly in conjunction with an aging mass airflow sensor, especially when the engine is spinning up quickly on the dyno (perhaps with an inappropriately small flywheel?).

Is the engine tuned? Not really, with a maximum torque of only 375 Nm...

Hi Chris,

Have the values from the fuel temperature sensor been checked for plausibility?
Otherwise, Ulf's assumption is quite plausible -> Log data from the boost pressure would be helpful.

Hello,

I completely forgot to post the results here .

I just wanted to follow up on that.

The engine misfire was caused by a completely clogged EGR valve, which resulted in the engine running too rich, leading to the misfire or even occasional stalling.

@Ulf

The engine was a standard model.

Best regards,

Chris.

Chris wrote:

The jerking was caused by a completely clogged EGR valve, which resulted in the engine running far too rich, and this caused the jerking or even brief stalls... The engine was standard equipment.

Yes, yes, a beautiful new world of PD.

You might initially think that smaller and fewer soot particles would prevent the intake manifolds from becoming as clogged as in the previous generation of vehicles, but you'd be wrong...

Hey everyone, since I found my performance chart on Google... *lol*, I decided to sign up.
So, as I mentioned, the performance graph shows the steep torque drop that's characteristic of my stock ARL engine.
Although it's still under warranty, the workshop can't find anything wrong.
Does anyone have any ideas about what I could do?

Devilseye503 wrote:

Does anyone have any ideas about what I could do?

Yes!

Either log the values using VAG-COM and post them here (see the technical article --> systematic troubleshooting with VAG-COM), or first check if the error that the original author experienced might also be present in your case (AGR).

Wishing you lots of fun!
Guste.

'So, I don't have the same issue that Chris does - it's been checked.'

I would like to do that with the VAG-COM, but unfortunately, I don't have an adapter .

Devilseye503 wrote:

So, I don't have the same error as Chris - it has been checked.

Very good, but why didn't you write that in your initial post?

Quote:

I would like to do that with VCDS, but unfortunately, I don't have an adapter

.

Without any data readings, any diagnoses I could give you would be pure guesswork. This kind of thing isn't really done or supported in this forum. If you need to, read through the technical articles. They list the "common errors" (all filters, 109 models, NHG, VTG, etc.) and offer troubleshooting/testing suggestions. If you like, you can check them all out based on suspicion.

Here's the translation:

"As for alternatives, there's only one: measurements. To obtain these, you absolutely need the adapter. However, these are now widely available. Why don't you ask around among your acquaintances? The next alternative is to acquire one yourself. You could try your luck on eBay, which I strongly advise against, as they often don't perform as promised. Or, you can buy one here in Rainer's shop, either as a complete device or as a kit. Both options are still under 100 euros. While it's more expensive than on eBay, it's guaranteed to work. Besides, it's still cheaper than most visits to a workshop..."

Regards,
Private.