Caddy Idle Speed: CFHC Adjustment Guide

Hello,

This is my first post, and I ask for your understanding in advance if I miss something or do something wrong .

Brief introduction:
I live in Nuremberg and have general knowledge of automotive technology, but I have more experience with gasoline engines than with diesel engines.

Problem:
Caddy, year 2010, 2.0 l engine, model CFHC, 196,000 km.
The AGR cooler/valve was replaced by the workshop, and since then, the engine speed has mostly been around 950 RPM.
The DPF was not cleaned, and VCDS shows a soot volume of 0.13 liters.
Before the repair, the idle speed was usually around 800 RPM, while the regeneration speed was around 1000 RPM.
"Currently, the engine speed is often increased to 950 RPM, but it doesn't appear to be regenerating because the fans aren't running and the DPF cover isn't getting hot."
You can almost touch it; it's that warm. The current outside temperature is 0-5°C, and the oil temperature is between 60 and 80°C.
Occasionally, it regenerates, which is clearly noticeable due to the fan activity and temperature readings.

Question:
Why is the speed constantly being increased?
Is it due to the outside temperatures, or was something done wrong during the repair?
After consulting with the workshop, they are being stubborn and say "Everything is on track," which they are probably right about.
Can I use VCDS to log any values to gain more insight and potentially have a better basis for discussion with the workshop regarding further repairs?

How can I use VCDS to determine if regeneration is occurring while driving?

Thank you in advance.

Best regards, HansGerch.

Especially with low outside temperatures and the weather we're experiencing these days, you should check which appliances are running. Heating, lighting, and air conditioning can all cause the LL (likely referring to a motor or pump) speed to increase in order to provide the necessary power. Additionally, there will naturally be a longer warm-up phase.

It's hypothetically possible that the AGR (Automatic Gearbox) isn't functioning as it should, but that should already be monitored by the engine control unit (ECU).

A car scan would be very helpful. You can already check the distance/time between regenerations. What load was set after the cleaning?

Have you checked all the engine data blocks and looked at them? I would expect there to be a block that explains the reason for the increase (probably a bit matrix).
It's at least worth a try. However, I'm not entirely sure about this.

@matthias:
The power consumption consists only of the lights, radio, and ventilation, all set to automatic. No power-hungry devices are in operation.
It has been approximately 150 km since the last regeneration. The "Kilometers since last regeneration" value was read using VCDS.
The DPF was NOT cleaned, and the ash volume remained constant at 0.13 liters.
Please find the Autoscan attached. No errors were found except in the navigation system, which is not relevant.

@guste:
Where could I look for this information? Which data blocks should I examine? What search terms should I use?

During the 150 km drive without regeneration, the idle speed was practically always around 1000 rpm, only dropping to around 800 rpm after being under load and having reached sufficient operating temperature. After stopping for 10 minutes, the idle speed increased again and remained at that level.
I'm simply puzzled that before the EGR valve was replaced, the engine speed was consistently around 800 RPM, regardless of ambient temperature or engine temperature.

HansGerch wrote:

@guste: Where could I look for it? Which measurement blocks, which search terms?

Engine control unit 01.
Click on the "Measurement Value Blocks" function and then click on the desired block. I would expect to find it within the first 100 measurement value blocks.

If the control unit already supports extended measurement values including the search function, I would simply scroll down and check what it offers. Alternative search terms I would try are: idle, speed, increase, load, demand.
Regards,
Guste.

Okay, I'll be able to do that tomorrow.

"Possibly a silly question: Does the engine need to be running, or is 'ignition on' sufficient?"

To search and locate it, the ignition is sufficient. If you do this for a longer period, it's safer to connect a charger. To see what's happening, the engine will obviously need to be running.

Hello,

Is the battery okay? I don't want it to be constantly trying to charge.
Have you already checked the vehicle's onboard network control unit using VCDS?

Best regards, Rainer.

The battery is a good recommendation; it's likely still the original one.

Autoscan:
Batt.-Spannung Start/Ende: 11.5V/11.8V. VIgn 11.7V

It will probably be necessary to get a new one after 12 years .

Feedback will be provided by Monday at the latest.

Hi,
The voltage values are not very informative without specifying the boundary conditions. What is the battery voltage at the terminals after a night of inactivity (without turning on the ignition)?
The battery management system can be a bit peculiar. It only charges the battery to 80% due to regenerative braking, and there can already be frequent periods of increased speed. I have this on my Golf 7, and I want to take a closer look at the system after I replace the battery.
hg
Herbert.

2 days of inactivity, ignition off: 12.05V.

Quote:

It looks like a new one will be needed after 12 years icon_wink.gif

Yes. You can still try charging it externally or by taking a longer trip, but that will probably just waste time.
hg
Herbert.

HansGerch wrote:

2 days of standstill, ignition off: 12.05V

She's flat.
First, let's replace the battery and see if the increased LL (low-level) speed issue resolves itself after the first full charge.
Regards,
Sure.

Here is the translation of the text from German to English:

"Guste" is a German word that means "gust" or "gust of wind." It can also be used as a verb, meaning "to gust" or "to blow."

Here are some examples of how the word "Guste" can be used:

* "Der Guste wehte stark." (The gust of wind blew strongly.)
* "Der Wind gustete." (The wind gusted.)
* "Ich gustete." (I gusted.)

I hope this helps!

After replacing the 7-year-old battery, everything looks good.
However, I could only take it for a short test drive, so the final report will be ready next weekend.

Thank you for your help!

Caddy is behaving normally again, with an idle speed just below 800.

It's quite astonishing how quickly people jump to conclusions and accuse someone, which just blocks their ability to think clearly... I've been suspicious of the battery for a while now, and it was actually on my to-do list.

Best regards, HansGerch.

Thank you for the feedback .