Car starts fine and runs fine up to around 55 mph and as long as I stay around this speed all is well. After a minute or two at 60+ mph the amber warning light comes on (something to do with emissions). If I keep my foot on the throttle there would appear to be little if any change, however if I slow down and change down gears then climbing back up through the gears is slow and it feels like there is a limiter working away to keep the vehicle at a slow speed. If I ease off the throttle for long enough the light will sometimes go out and will stay out so long as I drive 50 mph or slower. Another thing that makes the light go out is if I go around a roundabout. This may sound ridiculous and I admit I cannot seem to recreate it by turning sharply but it has happened often enough (about 7 or 8 out of 10 times) that it has to be more than coincidence.

After reading other threads here I have checked all hoses for splits and holes but found none. All hose clamps are tight. I also replaced the air filter and at the same time removed and cleaned the MAF sensor but with no change. I know my fuel pump (located in wheel arch) is working fine. Other threads have led me to believe there is another fuel pump somewhere but I can’t find it, so if anyone thinks that is the problem perhaps they could also point me in the right direction.

Taking it to a mechanic is not an option due to my location (small Caribbean island) so any thoughts on the matter greatly appreciated.
 
I had a similar issue with mine last week,
Turned out to be abit of corrosion to the injector plugs,
My fault gradually got worse over around 2 weeks and even started staying on when I parked her up.
But I just took the injector plugs off 1 by 1 give them a little clean and hey presto faults been clear for over a week
 
See attached photo for easy access
 

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On mine I found second from left had a small amount of dust visable in the plug, quick squirt with wd40 (other maintenance sprays are availiable ) and jobs a gooden.
Didn’t even look enough dust to break the contact but must of been, as after the second week fault was still happening when parked up, and only found it by leaning on the engine cover whilst running as I was checking the pipes down the back and the turbo breather filter and the tone of engine changed and fault cleared.
I also changed fuel filter, air filter, checked turbo acuator and all the usual stuff was ok before I found the fault,
But started off only occurring at 70mph plus and would go out when eased off the accel (obvs no fuel demand)
Good luck mate
 
know my fuel pump (located in wheel arch) is working fine.
Have you checked the live data for the low rail? The LP pump should give over 300Kpa under full power and over 350Kpa at idle.
Other threads have led me to believe there is another fuel pump somewhere but I can’t find it
There's only one LP pump on that year.
so if anyone thinks that is the problem perhaps they could also point me in the right direction.
Read the codes and look at live pressure data before getting your hands dirty. ;)
What year is it and have you had the codes read?

It's a 2005. I'm guessing no codes have been read.

Sounds like the normal low rail pressure problem to me. Looking at the live data would prove that.
 
Have you checked the live data for the low rail? The LP pump should give over 300Kpa under full power and over 350Kpa at idle.

There's only one LP pump on that year.

Read the codes and look at live pressure data before getting your hands dirty. ;)


It's a 2005. I'm guessing no codes have been read.

Sounds like the normal low rail pressure problem to me. Looking at the live data would prove that.
I will leave this one in your capable hand Nodge :)
 
Just the electronic connections, not much messing 3 bolts or so for the cover and each plug is clipped on,
Mine brought up no codes but it was a cheap code reader from China
 
If the low pressure fuel pump is NOT the one in the wheel arch, can you tell me where I find it?
Thanks to all for the input so far.
 
If the low pressure fuel pump is NOT the one in the wheel arch, can you tell me where I find it?
Thanks to all for the input so far.

The LP pump is in the rear arch, along with the filter and sedimenter.
It's a known problem that it's output pressure drops as it wears out. This is why the live data is so important, as it'll tell you the pressure the ECU is reading. If the ECU sees the LP rail is below a predetermined pressure, it puts the MIL on and limits power to prevent damage to the High Pressure pump.
 
Hi. Had the same issues on a 2006 TD4. Got all the filter, pumps, EGR, Breather,changed cleaned etc. None of it worked. The answer was to replace the Turbo Boost Solenoid Valve (STC4198). It controls the veins in the Turbo at certain speeds i.e. above 60 or under heavy load. Buy it on line for around £40 plus VAT. If you can get underneath you can fit it yourself, couple of bolts and some pipes, if not a garage can do it inside an hour.
Absolutely no issues now.
Original Thread "Engine Malfunction Light AHHHHHHHHH"
 
I'd also recommend changing the boost control solenoid if the engine loses power at higher rpm but drives fine at low rpm. It seems to be a common failure on the TD4 causing the exact symptoms you describe.
 
Hi. Had the same issues on a 2006 TD4. Got all the filter, pumps, EGR, Breather,changed cleaned etc. None of it worked. The answer was to replace the Turbo Boost Solenoid Valve (STC4198). It controls the veins in the Turbo at certain speeds i.e. above 60 or under heavy load. Buy it on line for around £40 plus VAT. If you can get underneath you can fit it yourself, couple of bolts and some pipes, if not a garage can do it inside an hour.
Absolutely no issues now.
Original Thread "Engine Malfunction Light AHHHHHHHHH"
Thanks
 

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