Measured air greater than reference 1.6 HDI

[aelfric]

Citroen C3 Picasso with 1.6 HDI engine. No DPF from factory on this model.
Measured air at idle is about 400mg, reference air is about 260mg.
I have seen suggestions that the reference air should be about 380/390 or so. Is that correct which would mean something is messing up the reference calculation?
New EGR fitted and passes actuation test. New intercooler hoses fitted. New seal for air intake to rocker cover. New rocker cover. MAP sensor values look sane. Turbo pressure sensor values seem sane. Waste gate actuator holds vacuum and moves on start up.

Any ideas?

[mickthemaverick]

Hello and

You don't actually say what the problem is with the engine's performance which made you start changing all the parts?

[aelfric]

EGR was changed due to P3008 air flow sensor signal - air flow too high
Then MAF was also changed.
It has since failed MOT on emissions.
Air flow readings have stayed constant throughout.

BTW car is a 2009 model

[PaulC5]

To fail MOT on emissions that must mean there is too much soot in the exhaust. If it has a dpf is that in place and working ? Have you checked the MAF wiring and for any air leaks ?

[aelfric]

No, no DPF on this model. I put a new plug on the MAF wiring.
An air leak would surely lead to lower air flow readings, not higher than reference.

[aelfric]

I took the car to a Citroen specialist and they could find nothing physically wrong with the engine so they reloaded all the emissions parameters in the ECU and that was good enough to get it to pass the MOT

[windy1603]

Was the new EGR programmed into engine ECU when changed as that could have caused the issue as it did not learn the new limit values. The reset of all the parameters would have put it in learn mode

[wheeler]

Has someone blanked the EGR off? 400 mg/cp at idle would suggest to me that the EGR valve is fully closed or its been blanked off, remember it could be blanked anywhere along the pipework however i wouldn't expect it to fail an MOT with just the EGR blanked.
Has the engine management warning light been on?