Td4 leak off test results

Hi all.
I have just carried out a leak off test on my 2006 TD4. Symptoms - Hesitation, blue smoke. This is what I got after 2 mins of idle of a hot engine.
Injector 1 - 60ml
Injector 2 - 70ml
Injector 3 - 40ml
Injector 4 - 70ml.

Looking at these results, am I right in saying that injectors 1,2 and 4 should be attended to with 3 being the best one?

Thanks.

Not necessarily, unless there's particular running issue.
What Freelander is it? An FL1 or FL2?

I was under the impression a common rail leak off test only really told you which injector was passing to much derv when cranking, ie it takes loads of cranking to start it, but once running it is fine.

lynall said:

I was under the impression a common rail leak off test only really told you which injector was passing to much derv when cranking, ie it takes loads of cranking to start it, but once running it is fine.

Click to expand...

Correct.

A leak back test is of little value on a common rail system at any speed over cranking speed. Then if one injector spills masses of fuel, it's likely to be on the way out.

The injectors will always spill a bit when the engine is running, simply by design, so similar amounts of spill are often inconclusive.

Using a suitable diagnostic reader which shows injector offset is the best way to test injector performance in the vehicle.

The only true test of injector performance is on a dedicated test rig, which measures spray pattern and flow capacity, reaction times and a host of other complex dynamic properties.

Nodge68 said:

Not necessarily, unless there's particular running issue.
What Freelander is it? An FL1 or FL2?

Click to expand...

FL1 - Blue smoke at 2000 rpm with a smell of diesel too. Also, idle can be a bit lumpy. Also, black smoke at full throttle! Pressure reg. O rings have been done and MAF has been changed to a Pierburgh with the RonBox. BMW breather done too. All intercooler hoses replaced. I have inspected the fuel rail sensor and there was green deposits in the plug - Updated sensor and loom have been ordered. A puff of blue smoke is there on startup as well as the 2000rpm puffs. According to others, this could be a sign of a leaky nozzle in an injector. Yes, some live data would be great when I have enough £ to buy a proper FCR. I have a spare set of injectors from a known good engine to try at the weekend. Are there any tell tale signs I should be looking for when inspecting the old ones? - Thanks. Scott

You cannot tell the condiiton of an injector by visual inspection alone, unless there is something massively wrong, ie its melted or has damage from engine issues.

Stick the spare set in, that will at least give you an idea whats going on, and hopefully where to look.

ScottStephen said:

FL1 - Blue smoke at 2000 rpm with a smell of diesel too. Also, idle can be a bit lumpy. Also, black smoke at full throttle! Pressure reg. O rings have been done and MAF has been changed to a Pierburgh with the RonBox. BMW breather done too. All intercooler hoses replaced. I have inspected the fuel rail sensor and there was green deposits in the plug - Updated sensor and loom have been ordered. A puff of blue smoke is there on startup as well as the 2000rpm puffs. According to others, this could be a sign of a leaky nozzle in an injector. Yes, some live data would be great when I have enough £ to buy a proper FCR. I have a spare set of injectors from a known good engine to try at the weekend. Are there any tell tale signs I should be looking for when inspecting the old ones? - Thanks. Scott

Click to expand...

Let's break this down into sections.

Blue smoke at 2k RPM off load, normally accompanied by a misfire, is the M47R 2k misfire, for which there is no definitive cure. I believe it's oil from the breather system being drawn in under light throttle, but I've never been able to prove it.

Blue smoke is oil burning in small quantities, which isn't injector related, but is down to normal wear of the engine, particularly valve guide seals. This is the most likely cause of the blue smoke on starting. The oil makes its way down the inlet valves slowly after shutdown, being burnt off at the next start. It's no cause for concern.

A slightly lumpy idle is more important, and could relate to an injector issue, but it's doubtful that a simple spill test will show which injector is to blame. It could also be down to the corrosion on the rail sensor.

Black smoke under full power isn't any concern in a turbo diesel, providing it's getting full power.

Fitting a Synergy 2 and Pierburg MAF often results in black smoke at full power, which is why I turned mine off for the MOT. In normal, non MOT mode, then it made black smoke when running at full power.

Black smoke isn't necessary coming from the engine at the time it's visible. Normally this smoke is soot which has built up in the exhaust system, that clears out as the engine approaches full power, when the exhaust gets hot, and gas flow rate is high. This is normal for a diesel which spends most of its life at part throttle. Diesel engines like to be run at full power all the time, or the whole system clogs with soot, which is then expelled under full power operation.

I'd not mess with the injectors, until you know that the MAP sensor is clean, the inlet manifold is clean, and the EGR valve is sealing, or is removed completely.