C3 Picasso has started rattling...

[kiwimike]

Hi folks,

Hope you're all doing well.

I have a 2014 C3 Picasso. It has the Tu5 EC5 1.6 16v engine, variable valve timing and flex fuel (petrol and ethanol). Automatic AL4 4 speed.

We just did a 1000km (600mile) road trip. During the trip a rattling started - not suspension. Since there were 5 people in the car and conversation it was hard to give it any attention other than a quick look under the hood.

The engine receives regular oil changes and 10,000kms ago i changed all the belts (timing + accessory) and tensioners with INA replacements. The car has given us very few problems. Its got 80k on the clock.

What i've observed so far:
So it'll rattle driving on road and it'll rattle while stopped. I got my wife to change gears while stopped, engine running of course, with my head in the engine department it really is a sharp rattling that absolutely seems to be coming from inside the engine. It momentarily sounds like a diesel. It'll do this when the load upon the engine is being changed. I've never been next to a car with predetonation, slap or knocking issues, but i'd imagine that it sounds like this. There is no temperature gauge on our model so i couldn't even tell ya if it was running hotter than usual.

When cold, it doesn't rattle. I just went on a 15 minute test drive and it didnt come back... But then i thought to turn on the AC. It started. So, while the AC is on, a change in load brings on a brief rattle.

So i've just put the car on my diagbox scanner. The only fault code thrown is an intermittent "braking pressure sensor fault". Which is new but it has cleared. Will have to do another test drive to see if it comes back.

I did have the AC system re-gassed a few months back. Functioning perfectly. We rarely drive without it on in our part of the world!

Anyone got any ideas at what i could have a look at??? After writing this i'm hoping its just a bad batch of fuel, which is not unheard of around here, since we haven't filled up since we got back... but the sound is pretty alarming.

Cheers,

Mike

[GiveMeABreak]

Mike, Hi and welcome.

First, to avoid any possible confusion I have modified your profile and the thread title / post to remove any references to 'Aircross' as the European and non-Mercosur country models of the C3 Aircross were not launched until 2017 and the C5 Aircross until 2018.

What you have is a the special edition of a C3 Picasso from which they developed an SUV specifically for Mercosur countries, made in Brazil from 2010, so won't be a model familiar to many outside this region:

Thought I'd just clear that up as this model was not available elsewhere and may of caused some confusion being a 2014 model.

Second, if you pop your VIN up (automatically masked on post submission) I'll see if I can clarify model and engine - but there is a chance it may not come up with Citroen Europe.

[kiwimike]

No worries Marc!

VIN 935************** (VIN Masked, can be read by Forum Staff)

Thanks.

[GiveMeABreak]

Ok, so confirmed as a C3 AIR CROSS / PICASSO (LATAM) SUV 1.6 VTi 16V 115 (EC5) 4-SPEED AUTOMATIC GEARBOX.

Have you checked the pulleys / tensioners? These can rattle with age.

[kiwimike]

Ok, so confirmed as a C3 AIR CROSS / PICASSO (LATAM) SUV 1.6 VTi 16V 115 (EC5) 4-SPEED AUTOMATIC GEARBOX.

Have you checked the pulleys / tensioners? These can rattle with age.

Cheers Marc, unfortunately its definitely a knock.

[kiwimike]

So i've been slacking on investigating this issue. Its definitely a knock.

And it'll do it under load even when cold (ambient temp here is 30+ deg Celsius). So as far i as know it leaves a lean air/fuel condition, carbon build up, EGR, knock sensor or plugs (gaps) as possible causes.

I replaced the spark plugs with new ones because they've never been changed since new. Made no difference.
No EGR system.
I can't find a knock sensor in lexia???
Lean air/fuel makes sense to me because the sound of the fuel pump has changed in recent months so thats the first suspect.

So today i connected up the lexia...

I was hoping to have a look at the short term/ long term fuel trims... but lexia only shows the most basic of info of which the only relevant reading seems to be injector timing. The value at idle is 2.56ms... apparently it should be 3-5ms. Except that value would seem to indicate fuel pressure is fine wouldn't you agree??!!

Using a generic obd reader... short term fuel trim varies between 8.5 to 15, while LT is stuck on 40%. How to interpret this i'm not sure.

Any ideas!?!?!

Cheers