Severe misfire.

Hi all. Need some help with my long suffering wife's TD4 (04 plate) and it's driving me nuts at the moment and I'm hoping you guys and girls can help. Bit of a long one so stick with it.
Picked her up last year with a shot clutch, I knew the vehicle before I bought it and was running fine until I got my hands on it.
Replaced the clutch but from the get go it ran like a bag of old nails, misfire and lots of white acrid smoke. While doing the clutch I noticed the EGR was clogged solid so took the inlet manifold off and gave it all a good clean. Inlet manifold had new seals when re-fitted.
Found a couple of vac pipes that were holed so replaced the lot. Plugged in the Hawkeye and it showed #1 injector was iffy so replaced it and the fault moved to number 2 so replaced all 4 with recon units. Didn't help.
Just fitted 4 brand new genuine LR injectors and number 1 and 2 are showing -6.0 but 3 and 4 and showing +6.0 and feels like it's basically running on 2 cylinders.
Checked the injector wiring loom plug at the ECU for corrosion, all good. Checked the conductivity of the loom and again all good. Pulled number 3 and 4 out again to check that they were seated correctly and again all good.
Apart from the spurious injector readings there are no DTC's coming up.
It's as if #3 and #4 are starved of fuel.
I have no idea where to go next but I can't help thinking that somewhere along the line I've done something while changing out the clutch.
Any help would be appreciated.

White smoke is usually unburnt/over fueling. Is the injector return feed blocked?

No doubt a Gaylander expert will be along to groom advise you soon.

GRATCH said:

White smoke is usually unburnt/over fueling. Is the injector return feed blocked?

No doubt a Gaylander expert will be along to groom advise you soon.

Click to expand...

Checked the return line and it's clear.

If the injectors are all new and it's still not running correctly, then it could be low compression, especially if the 2 cylinders affected are adjacent to each other. It could have a head gasket fault between the cylinders, although the is extremely unusual on a TD4.

I'm assuming you've checked the rail pressure sensor is corrosion free.

Have you tried moving the injectors about, to see if the fault follows the injectors, or always remains on the same cylinders?

I'm going to pop 1 and 2 out and swap it with 3 and 4 this morning and see if the fault moves. Plug on the rail sensor is clean and while running gave the plug and loom a wiggle to see if it made a difference but nothing.

Might be an injector, I know they're new, but hey ....

Have you checked the MAF ... taken it off see if the miss stays ... clean it, carefully ...

Air cleaner ?

Common rail sensor ?

Unplugging the MAF while running does make it run worse, if that's possible, so confident that the MAF is doing it's job. If the common rail sensor was faulty wouldn't if affect all 4 cylinders equally?

Landybitz said:

Unplugging the MAF while running does make it run worse, if that's possible, so confident that the MAF is doing it's job. If the common rail sensor was faulty wouldn't if affect all 4 cylinders equally?

Click to expand...

Yes and usually ...

Update. Got her running and unplugged each injector in turn, #3 made little or no difference. Put a probe into the loom and could see it pulsing but strongly suspect it could be the loom at fault.

I'll be keeping my eyes on this thread if you don't mind. My misfire on idle isn't bad just a little lumpy on cold with white smoke. Clears once warm.