TD4 lumpy acceleration / intermittent lack of power

Hi all,

2002 Td4 Freelander manual, 183,000 miles.

Problem:
Intermittent 'misfire' at 50 mph or so, lack of power up hills, MIL sometimes comes on during episodes, but goes off again. Otherwise, starts and idles perfectly and accelerates very well on flat. No codes.

Already tried: Reading the sticky about lack of power...
1. Checked connections to injectors, fuel rail pressure sensor, MAF.
2. Cleaned EGR and blanked off actuator hose.
3. Checked vac accumulator and all hoses.
4. Replaced turbo solenoid and vent filter. Turbo linkage moves a good 20mm during acceleration.
5. Replaced crankcase breather filter (and general service).
6. Replaced LP fuel pump and filter.

Other features of problem:
Lumpiness is noticeable during revving in neutral - mainly 2000-3000 rpm. Also, when the key is in position II and the LP pump is running, I can hear hissing from the HP pump. There are no fuel leaks.

So... If the injectors were causing the problem, wouldn't I have starting issues? Could the hissing near the HP pump be air in the system, or some other fault? Since there are no leaks, could the LP pump be drawing in air through a pinhole, and if so, how do I approach that?

Many thanks in advance,
Andrew

Anyone?

What device are you using to read codes? I'd have thought that if the light's been on there would be a code somewhere.

GrumpyGel said:

What device are you using to read codes? I'd have thought that if the light's been on there would be a code somewhere.

Click to expand...

Well, it is an eBay crappy wi-fi unit, but as far as I can see unless I shell out for an expensive manufacturer-specific reader, I'll get nowhere. Something about UK EOBD standards lagging behind US OBD2...

Hi There.
(n1. Checked connections to injectors, fuel rail pressure sensor, MAF.)
Have you tried running it without the maf connected and if so did it perform better ? if yes then that could be your problem a failing MAF.


( 2. Cleaned EGR and blanked off actuator hose. )
When you say the EGR as been cleaned and blanked off is it a by pass EGR ? or the original EGR if the original then reconnect the hose and see what happens.

I would also remove the MAP sensor and give that a clean using carb cleaner do not spray direct into the hole.

Arctic2 said:

Hi There.
(n1. Checked connections to injectors, fuel rail pressure sensor, MAF.)
Have you tried running it without the maf connected and if so did it perform better ? if yes then that could be your problem a failing MAF.


( 2. Cleaned EGR and blanked off actuator hose. )
When you say the EGR as been cleaned and blanked off is it a by pass EGR ? or the original EGR if the original then reconnect the hose and see what happens.

I would also remove the MAP sensor and give that a clean using carb cleaner do not spray direct into the hole.

Click to expand...

Thanks, Artic2. I'll try the MAF unplug trick.

When I stripped the intake off to check connections I found the vacuum supply pipe to the EGR solenoid was rubbed through. It didn't look like this had JUST happened as the pipe was nearly broken in two. I fixed this and blanked off the EGR actuator pipe for good measure. I then pressure tested the vac system and it held. It is the standard EGR set-up so I'll reconnect so everything's back to stock set-up.

I forgot to mention - I did remove and clean the MAP sensor.

Wife has the car away in Aberdeen at the moment and I haven't had any complaints through - maybe something I did has worked. It's hard to know with an intermittent fault, and frustrating to poke at wires and swap parts without a proper diagnosis.

Cheers again,
Andrew

Tried the MAF unplug and reconnected the EGR - no change.

I also removed and cleaned the in-tank fuel pick-up unit.

Wife says the car is a little better but still lacks power at higher speeds and under load. My main suspects are MAF, given its age, and the HP pump, given the new hissing sound. I'll do an MPG check which will hopefully differentiate the two.