C5 2L RFJ Engine hesitation

[AviSa]

Hi,

I’m having severe engine hesitation with my 2005 2L C5 RFJ EW10A, from stationary, Sometimes up to 3 seconds.

When I hit the gas (gently or roughly) - the engine, sometimes, won’t rev up, it gently chocks (as if it is to rich or as if I’m quickly vibrating the gas paddle at idle) and then revs up.

Sometimes it will just pause without the choking before revving up, and on rare occasions it suddenly chocks and stalls when idling.

Similar, more gentle, behavior is encountered when returning to the gas paddle on 30 km/h – random delay but without the chocking.

It comes and goes with no apparent reason, even for days…

The engine performs well otherwise: responsive with plenty of power.

Some strange observation - a rough gear shift from first to second usually appear together with the engine hesitation.

- It happens when engine is cold or hot.
- No faults
- Throttle body cleaned and calibrated which seemed to made it better for 24 hours…
- Coil replaced with no effect
- Spark plugs replaced with no effect

I have exhausted my mechanic and Google…

Any help/ideas will be greatly appreciated.

Thanks

[Hell Razor5543]

I wonder what the airflow is like? If the air filter is clogged, or there is a blockage in the pipework the engine would not like it.

[AviSa]

Thank you, James, for the prompt response and the idea.
My list of possible causes is so full with EGR, ECU, PCV and such - that I totally skipped the obvious…

Will check that.

Thanks

[GiveMeABreak]

Check out the air filter first as James has suggested, make sure there aren't any leaves or other rubbish in there. It's also possible the MAF (Mass Air Flow Sensor) may need cleaning or is faulty. There is a quick test to see if this may be suspect. You can temporarily unplug the sensor from the MAF and then run the engine and see if it is any worse. This action will normally put the car into 'limp home' or reduced performance mode - but it should let you see if there is an improvement on idle speeds or gentle acceleration. If it sounds or idles noticeably better, then it is likely your MAF. These can be cleaned - but you have to be very careful not to touch the very thin wire in the MAF itself - it is very fragile. There are some specialist cleaners you can buy for doing this job - but most people tend to replace it.

[AviSa]

Thank you very much Marc.

I will update here my progress

[AviSa]

Sorry for the noob question... EW10A has MAP, MAF or both?
My best guess for now is MAP.

Went all over the web and could not find any reliable source of information about this engine... diagrams, parts numbers, location in engine bay.

Found this site http://service.citroen.com but I cannot register to it.

[GiveMeABreak]

Sorry for the noob question... EW10A has MAP, MAF or both?
My best guess for now is MAP.
Went all over the web and could not find any reliable source of information about this engine... diagrams, parts numbers, location in engine bay.
Found this site http://service.citroen.com but I cannot register to it.

Post or PM your VIN so we know exactly what engine variant you have.

[AviSa]

VIN is VF7**************[VIN obfuscated, can be read by forum staff]

Thanks Marc

[GiveMeABreak]

Right - yours will have the throttle body control valve then, Part 1635 X0 (No. 5 in the diagram). If these get gunked up they can cause bad idling and hesitation. Although you may be able to clean the butterfly valve in situ - a lot of the crud can gather at the back. There is a video on cleaning these below the diagram (it is a long one, but you can skip to the cleaning part - and is a generic procedure).

[AviSa]

Hi Marc,


My mechanic did that, including the throttle learning, with a non lasting effect... I will ask him to repeat the procedure.

Lexia is on the way.

Managed to hook up an iPhone app that shows that my idle RPM is at 700+- and the long term fuel % jumps briefly to 99.0% when I leave the gas paddle. Is this normal?

Where can I find the specs & diagrams for that engine?

BTW What is the part number for the TPS?


Thank you so much for the help & time

[GiveMeABreak]

No problems, the throttle body control valve is a complete unit PSA part number: 1635 X0, but don't forget you have the 'fly by wire' accelerator pedal too, Part 1601 Q4.

I can't help you with the idling readings as I don't have that information to hand.

[AviSa]

Update: MAP sensor and throttle body replaced with new ones by my mechanic without any noticeable change.

As the accelerator pedal is expensive one to replace – is there a way to check if the current one is ok?

Is there an “Idle Air Control Valve” in this type of engine?


Any help/ideas will be greatly appreciated.

Thanks

[GiveMeABreak]

So you have cleaned the Air Doser - Can you confirm you changed Part 8 on the diagram which is the Intake Air Pressure Sensor?

[AviSa]

Thank you, Marc, for sticking with me.

My mechanic did with replacemnet parts I got from eBay:

- BOSCH 0261230043 INTAKE MANIFOLD PRESSURE SENSOR MAP 1920.A ,96365830 ,96393814

- NEW GENUINE VDO 408-239-827-001Z THROTTLE BODY

[GiveMeABreak]

So all working now?