406oc.co.uk

Hi All I have a 2.0 hdi which is hesitant at 1350 to 1800 rpm noticeable more in 4th and 5th, if I am driving lightly and touch the pedal to go at these revs it hesitates but eventually picks up speed. If I "boot" it from low revs it flies off. I have changed 3 tps, 2 maf second hand ones. New genuine crank and cam sensors 2 new injectors with 2 tested high pressure fuel pump second hand, fuel rail and sensor, fuel filter casing, new EGR valve and electro valve, engine wiring harness, ECU and BSI . NO fault are showing on Planet and data seems OK apart from this problem the car runs good and as I say it flies with the foot down. Any help please. Other thought is if it could be a wiring fault or the turbo is struggling at these revs until it gets up to boost Regards

Hi, welcome to the club

To be fair, I would have suggested the MAF, then the TPS, but I would now be pointing the blame at a sticky/partially blocked EGR valve.

I see this has been done too, so how about the vacuum supply to the EGR solenoid and EGR valve? Do you have a way of testing the vacuum system?

By the way, do you have a 90 or a 110..??

Hi and welcome aboard.

I can't add much to GM's suggestions. When you say it flies from low revs when you boot it, does it do this without any hesitation / respond every bit as well as normal?
Sluggish EGR could fit the bill - I would blank it anyway as your car will run better and probably use less fuel. Might well sort this problem too.

Am I missing something as this sounds to me like turbo lag?
Poor acceleration in a high gear at low revs while driven gently (presumably at low speed) with minimum boost

1800 is where the turbo is effective from. My experience was always: boot, wait for it to creep up to 1800, then off you go.

Vacuum controlled boost if it's a 110?

Shuddering at low revs (12oo to 1400) in a high gear when you apply light throttle is symptomatic of a bottom engine mount. If you're light enough on the throttle then it shouldn't shudder at all, but when the engine mount is buggered it will shudder however careful you are.

I was thinking if the 406 is a 90, then its probably a MAF issue - if its a 110 then it could be turbo/boost leak related but I can't pinpoint why....

Hi All Thanks for the great response . I have changed the egr solenoid valve, at one point I blanked the egr off but made no difference at all to problem, I have changed the bottom mount. The MAF and the TSP that I have changed have been second hand but to have the same problem on 2-3 items would be odd?? Would the fault show on planet if it was the MAF? have disconnected it and no difference. Have since tried a gauge on the pressure pipe from the turbo to the wastegate actuator and only had 1 PSI at 2000 rpm increasing with revs over that, this was only stood still and not driving. It is a 90 bhp so no turbo valve. I have tried lots of things probably forgot about now am now thinking it could be a turbo problem or turbo lag but could this be overcome with a change of turbo or is it a built in problem?? Regards

Hi All just some more info 3 months ago I had to change the clutch due to it "kangarooing" at these revs, the clutch had broken 4 springs and worn into the centre plates where the springs sit. Yes it does fly from standing start and once over 2000 revs runs great. Bought this after my old 1.9TD that I had for over 10 years died with 350,000 on it not sure of the HDi's with some probs that I have read about but time will tell, I am on 149,000 now Regards

Someone on PEG on Facebook posted a photo of his HDI with over 800,000 km on the clock.... Yours has life left still!

Hi All Just an update I have fitted a New Genuine Siemens MAF sensor but with no effect anyone with any ideas I am struggling now. Do they have problems with the wiring to MAF if so anyone with a wiring diagram for it?? Any ideas about the turbo with only giving a low pressure under 2000 revs?? Regards

If you could record the diagnostics as you're driving and post a video up, that would be a huge help. I'm fairly familiar now with the expected parameters measurements on a 2.0 so I may be able to spot a potential issue. When you're watching the live data, does the measured turbo pressure deviate far from the expected value and if so is it consistently out by a certain margin or does this change when you're experiencing the hesitation? Lets face it this issue can only be air or fuel related, so my first port of call would be ensuring that correct fuel and air pressure is being delivered over all RPMs as any deviations will inevitably lead to a loss of power. Also, try cleaning the fuel pressure regulator, when these get dirty the high pressure pump can struggle to build fuel pressure at low rpm's and give sluggish response with black smoke too.

Hi fattail95 Thanks for the response. I will try to video the live data will use Pp2000 if you are used to that. Will try to clean the fuel pressure reg. Live data does not show the turbo pressure as it is only a 90 Regards