Greetings,

I would be grateful for thoughts on this from my learned friends:

HISTORY. This vehicle was bought a customer very recently and because it had been off the road for a few months decided to give it a service which included a new diesel filter. He also removed the catalytic converter (more power) and disconnected the vacuum pipe to the EGR valve (better performance/economy). Vehicle drove well as before for a few days and then developed excessive diesel smoke at about 2500 rpm and on start up. This was accompanied by a misfire at about 2500 rpm. He then replaced 4 injectors (uncoded), and after realising he had put the incorrect grade of oil into the vehicle (5-30w fully synthetic)changed to the correct grade of 10-40w semi-synthetic. All this made no difference and was taken to the local garage whereupon I was asked to have a look.

FINDINGS: No fault codes stored. The garage had already substituted a know good MAF. Inspected the EGR Valve and replaced its vacuum pipe. All pipes and hoses appear to be in order. The FRP sensor has been already been converted to the modified unit. I checked the software for a bad remap which was not the case. I have provided the following initial data:

Airflow: Idle 504mg/injection 2500rpm 560mg/inj

Inlet manifold pressure: Idle 100Kpa 2500rpm 110Kpa

Low Pressure Supply: 372Kpa 2500rpm 340Kpa

Fuel rail pressure: 28659Kpa 2500rpm 73618Kpa

What I have found is that the airflow measurement of 560 mg/injection is a lot lower than another TD4 I have checked and as the MAF appears to be OK, I am wondering if the lower figure is due to a restriction post MAF. Turbo for example?

So, before the garage decides to rave the Turbo out for examination, I would be grateful for your thoughts.

Regards

Pete M