155 THP Techno - Juddering When Idle

[rowdyangel]

Hi everyone,

hoping for some techie help here.

My DS3 155 THP Techno (reg July 2014) went in for a service at 10k miles about 3 weeks ago. Since getting it back I've noticed that when the engine is running idle, it seems to judder almost as though as it's about to stall.

It hasn't actually stalled though and when idle the rev counter is around the 750 mark. When driving it seems OK, no loss of power or anything like that and acceleration is fine. I have a 50 mile per day round trip, mostly motorway, so I want to make sure she's in tip-top condition.

I've read on another thread that this can be a common problem with THP's. I'm assuming it will need to go into Citroen for them to run some diagnostics on it but was just wondering if anyone has had this issue and what the problem was?

Many thanks in advance

[Jamie@SPTuning]

Could be your fuel pump, to be sure you monitor fuel pressure whilst it's doing its juddering, should be 48bar on idle

[TypeDS3]

One thing that may help if you haven't already done this, is don't put in 'basic/cheap' (including supermarket) petrol - use 97 RON minimum. This has been covered in other threads.

[Dangerousfish]

One thing that may help if you haven't already done this, is don't put in 'basic/cheap' (including supermarket) petrol - use 97 RON minimum. This has been covered in other threads.

The manual states that 95RON is fine, I don't recall any threads where it was suggested that ONLY 97 RON is used.

[Jamie@SPTuning]

Says 95/98RON on my filler cap

[Toxic]

Did they update the ecu when your car was last in he garage?
http://www.ds3club.co.uk/showthread.php?t=14651

[Toxic]

The manual states that 95RON is fine, I don't recall any threads where it was suggested that ONLY 97 RON is used.

I've heard other reports too that most cars engines and ecu's are designed for 95 Ron. Sticking in 97 can give more soot in your exhaust and effect the lambda sensors with very little increase in power. Think 5th gear done a test of 95/97 Ron in a Golf GTI with 4 rolling road sessions after each change of fuel brands. It showed 97. Was not that beneficial.

[TypeDS3]

Says 95/98RON on my filler cap

Jamie and Fish - total respect for you guys knowing far more than I do about this subject than I do.

I know it says 95/98 RON inside the filler cap, and maybe I made a mistake stating '97', but since having my engine cleaned after using mostly 95 RON petrol I have only put in 'superior' non supermarket Petrol (Citroen/Dealer recommended to do this) which has made it behave more like when it was new (ie when I first bought it).

Also, I can't always get to a Shell garage but when I can, I put in VPower Nitro which I believe helps running too.

Regards
Geoff

[Dangerousfish]

Jamie and Fish - total respect for you guys knowing far more than I do about this subject than I do.

It wasn't a dig or flouting knowledge, I just didn't want anybody mistakenly assuming they HAD to use a higher rated fuel at an additional expense, that's all

I know it says 95/98 RON inside the filler cap, and maybe I made a mistake stating '97', but since having my engine cleaned after using mostly 95 RON petrol I have only put in 'superior' non supermarket Petrol (Citroen/Dealer recommended to do this) which has made it behave more like when it was new (ie when I first bought it).

Also, I can't always get to a Shell garage but when I can, I put in VPower Nitro which I believe helps running too.

Regards
Geoff

There's no harm in using a higher octane fuel. You'll find plenty of articles online both for and against the use of it. Some will argue it's snake oil and others will claim they've gained an additional 200BHP since using it.

[lfcrule1972]

"an additional 200bhp" lol

[rowdyangel]

I took her into the Citroen garage and they ran diags. Nothing showing and couldn't identify the juddering with the engine running. They checked what they did on the car when it had it's 10k service a couple of months ago and nothing out of the ordinary on there either except for a "workshop intervention recall".

They want to keep the car for a full day so that they can have a proper look at it so she's going back in on Thursday and they're giving me another car for the day. Will see if they find anything. Just glad it's still under warranty lol. I did ask about the 95 vs 97 RON and I was told that 95 is perfectly fine for my engine and no need for 97 RON. Will post an update after Thursday but thanks to everyone for feedback and opinions so far

[rowdyangel]

Hi Toxic, yes they did update the ecu when it had it's 10k service a couple of months back. He mentioned that it was a "recall via workshop intervention" which I assume just means that it's something that needed to be addressed whenever the car went in for a service or other work.

[JEZDS3]

"an additional 200bhp" lol

Maybe 2hp with a following gust of wind!

[Toxic]

Has the dealership checked the inlet ports yet for carbon buildup?

[rowdyangel]

Has the dealership checked the inlet ports yet for carbon buildup?

Yes they said they checked that when I took it in last week