Engine Misfire on 2006 C5 1.6 HDI

[mark2256]

I have a citroen C5 1.6 HDI that has developed a running fault. On tickover it has a misfire and pumps out black soot over the road. I have run a diagnostic test on it and a fuel paramitter test using my Lexia that shows the amount of back leakage.

Cold Hot
Cylinder 1 +0.17 +0.44
Cylinder 2 -0.02 -0.44
Cylinder 3 -0.04 -0.07
Cylinder 4 +0.88 +1.16

Is this a diagnosis that injector 4 is sticking or blocked and would an injector cleaner rectify the problem.

Thank You in advance.

[Bick]

It does look that way how many miles?

[mark2256]

The car has covered 121000 miles and has an engine flush, oil (Castrol Magnatec 5W 30 C2) and filter change every 5000 miles. However I have now completed a leak off test and cylinder number 4 has the lowest amount of leak back with cylinder number 2 being the highest. So leak off test is inconclusive.

I have now removed the number 4 injector and the tip is covered in black soot and the resistance across the coil is 0.5ohms (is this value correct)?

Will keep you posted

[Bick]

not sure on the value and it does seem low mileage to be getting injector trouble?