Polymers on the inlet valves....

[Cliff Richard]

Hi all! :-0
We bought our 2011 DS3 a year ago and had a major service and GardX treatment. They advised it was due a free timing chain and tensioner replacement under warranty which we had done.
When we got the vehicle back it felt underpowered and had less torque.
They had put the latest "map" in the engine.
THere was a slight hesitation on part throttle and when I took it back they found no evidence of anything wrong.
Anyway to the point: the last month it has had the odd misfire under full load and this has progressively gotten worse.
Yesterday it went back and we were told it has a P1385 fault in cylinders 1,2 and 4 caused by polymer crustaceans on the inlet valves.
My query is this: prior to the cal chain and new engine map it was fine, immediately after it wasn't and has gotten worse. Could the engine map have caused the coking on the valves?
Next question is is this likely to recur and why don't Citroen cover this if it's a design fault of the THP motor?
Kind regards
Cliff

[BenS]

polymer crustaceans

Ummmmm........

On a serious note, inlet valve carbonisation is an inherent issue in all direct injection engines (i.e. most turbocharged petrol cars). That's why it's not covered - it's just standard wear and tear. Your coking would have been slowly building, but just got to the point of causing noticeable issues when you got the car back with fresh parts.

Yes it will reduce performance after about 30k miles and cause misfires if it is allowed to continue. A walnut blast at SPTuning will get everything back to its former glory though. The map has nothing to do with it (if anything it should run smoother on the new map without the carbonisation).

What mileage are you on?

[Cliff Richard]

Hi there and thanks for replying!
The mileage is 47,000 kilometres so around 30,000 miles, this ties in with your estimate!!
It's good to know and we will take the car in soon for the work.
really appreciate your response.

[Drummond Base]

Hi there and thanks for replying!
The mileage is 47,000 kilometres so around 30,000 miles, this ties in with your estimate!!
It's good to know and we will take the car in soon for the work.
really appreciate your response.

Mine was horrendously carbonated at 23,000 miles, ive seen them bad at well under 20k as well.