Turbo issues on remapped T6.1 204ps 4Motion Kombi T32: What's Causing It?

[timheyes]

Hi everyone,

I’m hoping to get some insights or advice about some turbo issues I've been having. I’ve got a T6.1 204ps 4Motion Kombi T32 that’s been remapped by Pendle. For the past 3 years, I've used it to tow a large double axle caravan to France, and for the first year, I had no problems at all.

However, things have changed in the last two years, and I’m trying to figure out what might be causing the issues.
Here’s the background:

• Year 1: Smooth journey, no issues.
• Year 2: On the way through France, I started getting the coil light with underboost errors. I could clear these by turning the van off and on again. On the return trip, I got an engine warning light related to the turbo. To continue the journey, I needed to clear the fault codes and turn the van on and off. VW replaced the turbo under warranty, and I assumed the problem was due to debris from an EGR cooler replacement done just before I went away.
• Year 3 (This Year): Same journey, and I’m getting the coil light again with the same underboost errors. This happens when the engine is under load (e.g., exiting a slip road, going uphill) and particularly in hot weather (~28°C). I drove cautiously to minimize these instances, didn't get an engine warning light, and now that I’m back home, I’m not having any issues.

A few more details:

• Between Year 1 and Year 2, I had furniture fitted into the van by Ply Guys (floor and two units, one with a big slide out drawer). The van was fully loaded for the trip.
• The issues mainly occur when the van is under heavy load and in hot weather.

So, my question is: What do you think could be causing the turbo issues?

1. Is it just that the van is pulling too much weight with all the added furniture and a fully loaded van?
2. Could the remap be putting too much strain on the turbo?
3. Or is it a combination of both?

Appreciate any thoughts, experiences, or advice you can share.

I’m trying to work out whether I need to de-map it, remove the furniture when towing, both, or something else

Thanks in advance!

(Picture of outfit for reference)

 

[DaveD]

I'm surprised VW replaced the turbo under warranty on a remapped van, you were lucky.
Anyway, did they show you the old turbo or explain in what way it had failed?
Is it possible that the old turbo was OK and that changing the turbo didn't fix anything, but you didn't put the engine under such load again until this holiday?
I'm wondering if your intercooler has failed, if it has a small hole in it that only causes issues under certain conditions, i.e high load.

 

[timheyes]

VW didn't know about the remap....

It was definitely a turbo failure as it went into them a few times before it was replaced. Initially they said it was the DPF and sent me on my way, but then I did a fairly big motorway run and the engine warning light came on again. I was recovered and assistance said they could hear a whistling. Then one of the main dealer mechanics drove it home and got the issue. They didn't say why it had failed.

I've been reading more and seen that a faulty/dirty EGR can also cause underboost so wonder if it could be that. I've found a post on a Ford forum that mirrors my issues: Towing with Ford edge 2018 sport

Interestingly in year 2, I did have some EGR codes as well:



This year it was purely P0299

 

[MB999]

I’ve been battling with this same issue.
Po299 underboost. Drives fine 99% of time but at 65mph ish when I cruise it throws coil light.

After much looking at stuff, with support from MMI on here, I eventually got it into my local Vw. Independent, vagrec nw.

He asked me if the van had been mapped.
I didn’t know as I’ve only had it a few months, previous owner didn’t say.
He Said turbo was working but at that rpm/load it wasn’t quite producing enough actual boost to match the specified boost requirements at the inlet manifold…. Suggested worn turbo, on its way out.
He also said it may be because it’s mapped it’s looking for that bit more and so with a slight drop in output it’s not quite making enough for the mapped demand.
Said it would prob be ok for an oem map demand….

I’m in the process of getting a replacemt on, so can’t advise if this cured it….. but after ruling out pretty much everything else I think it’s probably the likely cause.