someone please please help

[leeogt4]

So I've have my 54 plate td4 for about 2 mths now and it has been in the garage more than on my drive and is still missing and smoking under 2000rpm I've had all the usuall stuff done and all the injectors checked I just don't know where to go with this any longer and I'm on the verge of putting a match to the old girl lol any help would be so much appreciated

 

[PepeTheMule]

Hi, you say the usual stuff - what exactly?

Have you checked the intercooler hoses for holes?
Checked the MAF sensor?
Done a leak back test?

Smoking generally means over fuelling relative to air

 

[leeogt4]

Yeah had the injectors tested and leak back test was all within tolerance maf seems to be ok had all hoses changed for silicon ones, egr blanked off, crankcase filter changed, 2 oil changes

 

[Tiny1000]

"maf seems to be ok"....Have you disconnected it and ran the car to see if theres any difference

 

[hd3]

have you checked and cleaned the fuel rail sensor plug / socket ?

 

[jamesmartin]

i had one once similar it turned out to have 2 injector washers in one hole

 

[wammers]

"maf seems to be ok"....Have you disconnected it and ran the car to see if theres any difference

There won't be it's a diesel. MAF is for EGR.

 

[B34R]

There won't be it's a diesel. MAF is for EGR.

Not so on the BMW engines, we used to see this all the time on the bmw forums - cars running like crap and being underpowered usually turned out to be a faulty MAF.

For some reason the ones BMW fitted tended to only last about 40-60k!

 

[wammers]

Not so on the BMW engines, we used to see this all the time on the bmw forums - cars running like crap and being underpowered usually turned out to be a faulty MAF.

For some reason the ones BMW fitted tended to only last about 40-60k!

If the MAF fails on a diesel it can effect the ECU and confuse it. But the MAF is there to tell the ECU how much exhaust gas is being ingested when EGR is operating nothing more, it has nothing to do with fuelling. Diesels are throttled by fuel not by air. Under powered will usually be a malfunctioning EGR valve or system. Sort of makes you wonder how non EGR engine of the same type runs without a MAF sensor.

 

[leeogt4]

I've tried running it without the maf plugged in and doesn't seem to make any difference my garage has said today posible timing could be out or the ecu is knackered I've also tried kleening the fuel rail pressure sensor but to be fair didn't look too bad

 

[wammers]

I've tried running it without the maf plugged in and doesn't seem to make any difference my garage has said today posible timing could be out or the ecu is knackered I've also tried kleening the fuel rail pressure sensor but to be fair didn't look too bad

Nothing coming up on diag?

 

[leeogt4]

Nothing at all apart from when the maf was disconnected

 

[hd3]

But the MAF is there to tell the ECU how much exhaust gas is being ingested when EGR is operating nothing more,

td4 maf is pre-egr valve in the intake airflow system .. the maf sensor can't have a clue how much exhaust gas is being introduced via the egr valve
maf sensor voltage output .. determines how much fuel can be injected on go-pedal 'demand' without being over rich in mixture .. if maf be disconnected the ecu relies on an internal substitute maf mapping

~~~~~~~~~~~~~~~~~~
leeogt4 ..
make sure the egr valve .. if fitted .. is clean and doesn't stick ..
better still get rid of it altogether .. replace it with an egr delete/bypass unit
one thing less to go wrong and cause crap-engine-running issues ..
better mpg and go-pedal response without it ..

 

[leeogt4]

Is there any way of testing the maf ?without going and getting a new one or just un plugging it to see if it runs any different

 

[Arctic2]

Clean out the manifold, clean the MAP sensor, not the MAF sensor, and reinstate the EGR fully cleaned, and do not forget to check the EGR solenoid and its hoses,

 

[leeogt4]

Arctic2 Where is the map sensor located ?

 

[xpuser8334]

symptoms sound like the one i have on my driveway.
I ended up changing everything for the fuel system - in the end... it was the MAF.... no way of checking really. without unplugging or swapping.
I purchased a cheapy cheap eBay one for 27quid - only as a test.... it sorted the problem, so I bought a Bosch Complete unit.........
then I pulled out the engine to change clutch / slave master, and redo the brake pipes while the engine is on the floor...
two weeks later.. I'm almost ready to put it back in....

 

[xpuser8334]

On my TD4 - it's behind the oil filler cap, under the plastic air box lid... / head cover thingy..... on this one.... someone had cut the plastic to shape, so it didn't need the casing taking off to get to the sensor much more quickly.

 

[leeogt4]

I've tried unplugging it and no difference I guess I'll do the same and buy a cheap one to see if it's that problem

 

[xpuser8334]

new fuel filter and remote fuel pump???? or at least had them checked???