How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Robert Your Own Question

Robert, UK Qualified Car Technician
Category: Car
Satisfied Customers: 4540
Experience:  Fully qualified / self employed garage technician in the UK
Type Your Car Question Here...
Robert is online now

2008 c4 picasso excl - fully service history 75k a week ago

Customer Question

hi there
2008 c4 picasso excl - fully service history 75k
a week ago the engine became a bit weird
it is not smooth anymore
it is shaking when cold but even when it's hot it is not smooth. Changing the gear is not a problem it is something like a valve is not performing or something like this...any idea?
Submitted: 9 months ago.
Category: Car
Expert:  Robert replied 9 months ago.


2 litre petrol or diesel you have?

Any warning lights or messages in info screen pop up since this occurred?

have you had any recent work carried out on the car?

Customer: replied 9 months ago.
No fault message and norecent work apart from oil chnge and mot 2 month ago
Expert:  Robert replied 9 months ago.


If your refering to sticking valve causing compression loss resulting in one possibility but it would be hard to actually diagnose that without getting a proper compression test done on all 4 cylinders to see if thats the case or not then leading to leak down test to see which valve is at fault..not easy on the HDI's as you would need to test via the glowplug orifaces and removing them would need some care to avoid snapping..removing injectors can be tricky especially if they are siezed solid in the head.normally you need to hydraulically pull them out and even that cant be guaranteed if the cylinder head gets damaged....going by what your saying id be leaning to a possible injector fault a mechanical spray problem..check to ensure the oil level hasnt increased due to overfuelling .. to check injectors you would need to get those tested,leak back and such before any work is say that would be your first step from here..most well equiped garages should be able to perform that test and see what that brings up..

Customer: replied 9 months ago.
took it today to Citroen garage this morning and they were saying that it caused by the dpf (i think) filter and they recommended some fluid to add to the diesel before I take it to the motorway for a 30 mins ride. If it does not work I had to take it back for a diagnosis and service. I will give a go to the fluid first and will let you know whether the problem has been sorted or not.....
Expert:  Robert replied 9 months ago.

Normally that would come up as an "Anti pollution fault" having said that If the DPF was restricted you have a severe lack in power leading to cutting out..but you would have warnings up to verfiy that aswell as fault codes...added to that your car would likely have an Eolys additive fluid thats already injected into the fuel to help reduce DPF issues...If the car is missfiring severely both hot and cold as your describing to it run like that wouldnt be advisable in my opinion

What Customers are Saying:

  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil
< Previous | Next >
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, do indeed know your stuff. Jim
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C.
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex

Meet The Experts:

  • Greg



    Satisfied Customers:

    Automotive diagnostic tech
< Previous | Next >
  • Greg's Avatar



    Satisfied Customers:

    Automotive diagnostic tech
  • Matt's Avatar


    Mechanical Engineer

    Satisfied Customers:

    BEng hons Mech engineering, in auto industry 22 years
  • Ross's Avatar


    Diagnostic and repair technician

    Satisfied Customers:

    Licensed diagnostic and repair technician
  • Rob's Avatar


    ASE Certified Technician

    Satisfied Customers:

    30 years trade experience
  • uk_iaibal's Avatar


    UK Car Mechanic

    Satisfied Customers:

    Verified Car Mechanic.
  • Billy's Avatar


    Trainer/ Master Technician

    Satisfied Customers:

    Trainer 8+ years, master tech. 10+ years, SAE member
  • Mike Kelly's Avatar

    Mike Kelly

    Auto Service Technician

    Satisfied Customers:

    17 years experience as an auto mechanic, foreign and domestic. 5 years running my own repair business.