1999td5 90 flat on acceleration

I have an occasional fault on acceleration. I have looked but cannot find an answer, it starts first flick every time and pulls like a steam train but then for no reason i can find at pulling away there is no power and takes a few seconds until the revs build then takes off, change gear same thing then clears no problem for a couple of days then does it again. I have fully serviced with all filters,it has just passed its mot ,tried disconnecting maf sensor still did it ,would appreciate any advice as its really annoying

Hmm. Sounds like some sort of sensor problem is likely. As well as the MAF (by which I assume you mean the big airflow meter on the induction pipe near the air filter box), there are sensors on the air box itself and the inlet manifold. Have you had a play with these too? The one on the manifold is apt to get dirty, especially if you still have your EGR mechanism, so taking that out and giving it a clean with carb cleaner can help.

The other thing I've found with TD5s is that they're a bit vulnerable to fuel availability and pressure. Mine's a bit flat when it is just about to run out of diesel, for example. Is the fuel filter reasonably fresh, and are its rubber seals in good condition and sitting in their grooves properly? Is the fuel pump picking up and delivering fuel sufficiently well? The mesh at the bottom can clog up, and sometimes the pumps themselves lose the ability to deliver the 60 psi the TD5 engine prefers, even though you can hear them running. Is the fuel pump relay (typically one of the yellow ones under the driver's seat in a defender) in good condition. When I was suffering from a fuel starvation problem just after Christmas I found I could change the engine speed by waggling the pins on this relay, so I replaced it.

Anyway, that's a few more things to think about. Have a tinker and see what happens.

Thanks for the reply,yes the fuel filter is fine as i replaced this two weeks ago hoping it would be an easy fix and ive cleaned the sensor on the inlet manifold which was a solid block of rubbish,will check the other sensors on the air box.Not sure on fuel pressure but it had a new pump just before i got it about 18 months ago.It just seems weird that it clears as the revs rise because when it does get to a certain rpm it takes off like a scolded cat (it is chipped) .

Check the injector loom for oil it can get into the ecu and cause a signal fault to the injectors

thanks for that i was just looking that one up i will check this tomorrow at the ecu to see if there is any sign of oil

Oil in the ecu, was my intermittent fuel starvation fault it eventually took a replacement injector loom to correct the fault.. on the route to find this fault i also discovered the sensor in the inlet manifold was completely solid with black sludge..

Right here goes , checked red plug on ecu clean checked plug where it exits the head this is clean too.Checked sensor in air filter box can get no reading across any combination of pins with my multi meter but not sure if i would?.Could it be the egr valve sticking open,i took this off and it took a lot of force to open?have disconnected the vacuum pipe and blocked to see if this makes any difference
One other question why so many unused plugs of different forms all over the place.

kevinp said:

Right here goes , checked red plug on ecu clean checked plug where it exits the head this is clean too.Checked sensor in air filter box can get no reading across any combination of pins with my multi meter but not sure if i would?.Could it be the egr valve sticking open,i took this off and it took a lot of force to open?have disconnected the vacuum pipe and blocked to see if this makes any difference
One other question why so many unused plugs of different forms all over the place.

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Are well trying to cure any fault on line is difficult but at least you know that
Your ecu and injector harness are clear so that's the expensive bit out of the
Way
Ecr will cause this erect good idea is to clean the eve with carbon cleaner do the same if you can with the intercooler and inlet manifold
Hope you get it sorted soon