C4 2.0L HDI issues

[Captain Jack]

Hi there,

Not a Pug issue but my mum's Citroen C4, 2L HDI... The issue is that the car, erm, jerks. Basically, whenever the car is being driven by the engine (i.e. not coasting), it's jerking slightly. Almost like someone is constantly slightly pulling back off the gas pedal and back in quick succession.

It's generally relatively subtle but is noticeable. It's worse at some times than others. Plugged Lexia and it didn't come back with anything useful.

Here's the screenshot of the injector correction values.



They seem a bit ... off at more than 20% difference between injector 2 and 4 at idle. However, when I rev it, even slightly, all 4 injectors are showing 100.39%. I attempted to do a leak-off test but due to complete lack of space in that stupid engine bay, I couldn't get the tubes to stay in there firmly...

So.... injectors? 2 and 4?

Anything else that could cause it?

[madmadmax]

tps before injectors, the tps is the most likely to give that fault description and can cause a misfire type feel. you can check the tps with lexia

[Captain Jack]

My mum couldn't wait and took it to a garage who said it was some pressure valve. She couldn't tell me any more. £150 for the part

[jasper5]

Could have been this...

http://www.ebay.co.uk/itm/CITROEN-PEUGE ... 3a8bdf35e1

[piglet]

That sounds very similar to the fault I have spent years & £££'s trying to fix.
Local diagnostics bloke gave it a fair shot, agreed there was something there but couldn't fault anything.
Is the Citroen fixed and what did they change? Which injection system is fitted?

[Captain Jack]

I believe it's a Bosch system but can't be sure. The part is on order and is supposed to arrive today... whether it will fix it remains to be seen.

My dad, an ex-mechanic, apparently said that this valve could have been dunked in bleach to be "cleaned out"? Whatever that means... Jasper??

[Doggy]

Fingers crossed, CJ.

FWIW, I think you were on the right track with the injector correction values. Difficult to see that improving the pressure regulation will do anything to 'balance' those numbers, (but I could be wrong).

[Captain Jack]

Well, it could be that the numbers don't actually mean a thing and are within tolerance levels.

With the part costing £150 + labour, I certainly hope it fixes it. My mum isn't exactly flush with cash and I have a wedding to pay for

[jasper5]

I believe it's a Bosch system but can't be sure. The part is on order and is supposed to arrive today... whether it will fix it remains to be seen.

My dad, an ex-mechanic, apparently said that this valve could have been dunked in bleach to be "cleaned out"? Whatever that means... Jasper??

The valve I listed could have been the fault, but I haven't seen the car so no idea really, but if that valve was sticking it could have been cleaned out and made to work...doesn't happen in garages these days...they just replace instead of repairing.
The valve would have a needle inside.

[Captain Jack]

Sorry for the delay in replies. So the car is fixed. The mechanic diagnosed a faulty air doser and a sticky EGR. He cleaned the EGR and replaced the air doser for a princely sum of £276 The air doser alone was £150...plus coalition tax.

But seems to be working... Never thought an air doser could cause these issues. Though, I guess if the EGR was stuck open or semi open, the engine would be breathing exhaust fumes when trying to accelerate. It was idling more or less OK.

[Doggy]

Good to hear it's resolved, I guess it could have been even more expensive.

[Captain Jack]

Indeed. This was at a garage that I trust but he couldn't make aunty pollution go away. I used PP2000 and diagnosed a faulty DPF sensor, which I replaced - no more faults.

But happy that he made the right diagnosis first time.... now why are these cars so dirty inside?