TD4 strange misfire and smoking

Hi guys, pretty new here, and have recently acquired a 2004 freelander TD4. It's not got much history, but ran well until today.
I had a rubbing noise on deceleration, so dropped the prop and vcu to investigate. That's all going well, and I think the problem is just a vcu bearing, but... I planned to carry out a full fluids and filters service, so I started with the air filter. Since changing it I have a fairly heavy misfire between 2000-3000 rpm. I haven't changed anything else yet. I'm sure it's related to something I've done changing the filter, but it misses like hell with clouds of blue/white smoke and a strong smell of unburnt diesel. Anything obvious I should check? Symptoms are exactly like a knackered high pressure pump or injectors, but it ran sweet as a nut yesterday and I'm at a loss. No fault codes logged on OBD.
Any ideas much appreciated - I've checked injector wiring, all pipes and cables I can see, but nothing obvious! All the injectors seem to be working as unplugging them one at a time at idle results in a misfire as you'd expect. Car does have a Synergy box fitted and an aftermarket MAF, but they were on it when I bought it and it ran without any problems at all.
Cheers!

You sure the air filter cover was fitted properly? Not sure what would happen with a ronbox if the air wasn't going through the MAF properly.

When was the crankcase filter changed? If you don't know, them change it.
Also put a couple of doses of Comma Diesel Magic in the fuel and give it an "Italian tune up"

Also check to see what MAF is fitted. If it's a Pierburg, then make sure MAF Compensation is in the ON position on the Synergy.
Report back when done.

i'd be wondering about the maf and fuel sensor wiring
one thing regarding the synergy box .. is that the wiring should be no where
near the injector harness wiring .. if it is .. it will cause a mess up of the injector
signals from the control box .. ecu thing
( i ran my synergy maf wiring along where the brake-servo vacuum hose runs
( and made sure the fuel sensor wiring .. where in proximity to the injector harness
( crossed at a right angle .. no way should they run parallel and close to each other

that's all in the synergy fitting instructions
which i assume the OP doesn't have .. probably ..

sort of wonder if a wire to the maf has been accident pulled loose
or got crimped .. or similar ..
or ditto for the fuel rail sensor wiring ..

with the synergy .. it's also possible to get the maf connector fitted back-to-front
by accident ..
( although shouldn't be any need to disconnect that for an a.filter change )

only wiring that i mess with ( or used to 'till i did the intake mod )
when removing the air filter housing .. was the synergy fuel rail wiring
as i used the intake plastic housing thingy to keep the wiring securely in place
be just the way i routed the cable

Also check to see what MAF is fitted. If it's a Pierburg, then make sure MAF Compensation is in the ON position on the Synergy.

Click to expand...

+1
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here are the synergy ( ron box ) fitting instructions:
https://www.landyzone.co.uk/land-rover/wanted-synergy-2-fitting-guide.289415/

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Wow! Thanks guys. I've tried with the ronbox maf compensation on and off - no change. Thanks for the instructions, I'll have a good read.

Crank breather is on my list, as having searched on the forum for similar problems, I'll do that now and check the fuel rail pressure sensor and maf wiring too. As for the wiring, the maf wires run along the bulk head, and the fuel pressure connection runs along the injector wiring harness.

I've not yet checked which maf is fitted, but plugged into my mates snap-on obd, the readings are odd vs the 'expected' values for the td4.
The symptoms are very much like an injector failure, or hp pump, but I'm sure it's something I've done inadvertently whilst changing the air filter.
Will report back when I know more! Thanks again!!

So, quick update. Looks like a pierberg maf. I've checked all the wiring and can confirm it does not run along the injector harness!!
I've done the crank breather, which was clogged solid.
With the synergy off it misses and smokes, with it on it misses and smokes. I've removed, cleaned and refitted all of the electrical connectors around the maf and fuel pressure sensor. Also checked all of the intercooler pipes for leaks/damage and nothing obvious there either.
At a total loss with this now!!! I'm thinking the next thing is a road run and a good thrashing!!

Are you sure you haven't damaged or pinched a vacuum hose near the air filter cover? This could disable the variable turbo boost. Check EGR valve is not stuck open.

Locate the vacuum pump on the right hand side of the engine as you look from the front. Follow all the hoses from it.

Thanks,I have had a check and all seems well. I took it for a drive and it smoked like hell, for the first mile. Now all is well and the misfire has cleared. I wonder if it was upset because it could finally breathe for the first time in years!
Will see what happens when I next start it from cold.
Thanks for all the help. Great forum, hopefully I can contribute something to help others.
Cheers
Kev

Well, all appeared well, now it's cold again it's back to missing. Damned BMW engine!

You sure you fitted the air filter properly?
Not sure if it will go in the wrong way round but just asking stupid questions in case it prompts someone else to ask a sensible one.

wonder if the separate air intake temp sensor or it's wiring took a knock
when the air intake housing came off ..
( sensor be on the top intercooler hose )
wiring on mine ..where it connects to the plug .. were rather fragile ..
it had rubbed on the cable conduit edge .. insulated had come off ..
a slight tug would have broken it ..
( have since re-wired it )

btw: i don't know what year they changed that
as it were combined with the maf sensor on earlier FL1 td4's

and a fault with that evidently results in black smoke
https://www.landyzone.co.uk/land-rover/and-the-black-smoke.224520/

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btw: have a look thru this :
http://www.3.je/m47r_diesel.pdf
some differences .. essentially the fuel tank / l.p. fuel pump setup for later td4's
and be no variable vane turbo

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be a fault finding pdf file here ..
https://www.landyzone.co.uk/land-rover/75-zt-td4-fault-diagnosis.203935/

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Thanks guys. I'm really confused. I'm looking at the egr next, and tracing the vac hose to it. Interestingly, the temp sensor on the intercooler hose had a very tight cable, however, after rotating it a bit, all appears OK. I have noted that there seems to be a secondary air temp sensor as part of the synergy box, it's kind of welded into the back of the air box. Either way, the air temp on the obd seems to roughly match up with the outside temperature, so not sure it's that.
Interestingly, it runs absolutely perfect when up to temp, hence my thought that it could be the egr vac hose.
I'll take a look at the fault finding pages too, thank you.

Kev80 said:

it runs absolutely perfect when up to temp

Click to expand...

Faulty coolant temp sensor?

So, a few more developments. I've had a look at the vac hose to the egr, and have now established it has an egr blank/bypass fitted. Not sure that helps with the symptoms I have.
I think I'm going back to wiring issues for now.
Thanks again!

And some more: unplugging the maf makes it chug worse, much worse. Unplugging the fuel rail pressure sensor throws the MIL light on, and it doesn't want to rev at all. Think I mentioned already it's fine on idle, but unplugging each injector in turn and the miss follows it. I haven't managed to do this when the engine is revving as yet.
If anyone's got any other ideas I'd be more than grateful, and for the person who successfully identifies the issue, there's a box of old speckled hen in it for ya!

Oh, I've also removed the sump guard and undertray, is there anything down there I might of whacked and should check?
Can't hear any vac leaks using the old hose to the ear trick either.

something else to check:

there should be a small in-line filter at the end of one of the turbo-vaccum-solenoid hoses
it usually sits at the top-back left of engine .. more or less behind the maf sensor location
one end of the filter is connected to the vacuum hose .. the other end is left open ..
if that filter gets clogged up .. water / dirt .. the turbo vanes won't work properly
they'll stick ..

be not unknown for a prev. owner to relocate that filter
( or the filter is missing .. it's purpose unknown to the owner
( no filter would probably result in the turbo vacuum solenoid getting sticky or failing over time
if it were relocated further down .. be possible for it to get water-soaked
after driving thru standing road water ..
( same goes for the maf sensor 'n air-filter btw. .. would need more extreme conditions )

above issues have been posted on occasion by someone trying to fault find their td4's behaviour

that small in-line filter be service changed around 12k miles ..

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I've tried that one too, but thanks for the advice.

So far I've replaced the MAF, and have had a full new set of turbo hoses and a roll of vacuum hose delivered to fit. I'm also going to delete the swirl flaps.

I've spent some time speaking to Ron over at Tuning Diesels and he has helped a great deal with the fault finding. I'm still convinced it's injector related as I've seen the symptoms before, but will report back when I've changed it all, and stripped and cleaned all the actuator mechanism around the turbo and control solenoid.

Out of interest, where the hell is the fuel filter on these?

Kev80 said:

I've tried that one too, but thanks for the advice.

So far I've replaced the MAF, and have had a full new set of turbo hoses and a roll of vacuum hose delivered to fit. I'm also going to delete the swirl flaps.

I've spent some time speaking to Ron over at Tuning Diesels and he has helped a great deal with the fault finding. I'm still convinced it's injector related as I've seen the symptoms before, but will report back when I've changed it all, and stripped and cleaned all the actuator mechanism around the turbo and control solenoid.

Out of interest, where the hell is the fuel filter on these?

Click to expand...

Fuel filter is under the RH rear arch, just in front of the wheel.

You'll not be able to delete the swirl flaps though, as there aren't any.