Hi guys

I thought this was interesting/worth sharing.

A new customer came with this mondeo saying the car was fine but he thought it just felt abit different, he thought it was a little slower and had noticed slight smoking that he was sure, wasn't always there.

I test drove the car and to be honest it felt like it had enough power to me and the smoke really was minor. At first I thought it was just the begining of usual injector faults.

I measured the air flow through the engine by scoping the MAF.

I saw it was almost identical to my known good capture but not quite, the max output and rise time differed slightly.

I took out the air filter and the air flow improved slightly.

EGR looked like it wasn't that old and customer confirmed it was only replaced about a year ago.

The EGR is the next easiest to eliminate. Disconnecting the vac pipe didnt improve the profile.
Blanking the EGR off matched the profile up perfectly with my known good MAF profile.

I cleaned and smoke tested the egr and it seemed to function and seal correctly but, was still hindering the air flow when the engine was running.

I changed the EGR and the vehicle was fixed.

The customer was right, it actually was noticeablly smoother and more powerful and the smoke was non-exsistant, even though I thought it was running OK.

Here are the captures,




PINK= with air filter
PURPLE= without air filter
BLUE= after EGR was replaced

The rise time was also quicker in each capture.


This is the fixed mondeo against my known good MAF profile.




PINK= fixed car
BLUE= Known good

The max output and rise time are identical although the mondeo with the new EGR valve flows more air at idle now.

James