occasional limp mode cdti ZT

[mgmark]

I'm after some advice... since we bought the car it has occasionally refused to rev straight after starting, with a max of 1800rpm. This only lasted for a second or 2 then drove as normal. Didn't worry me too much as it happened rarely.

It's now started doing it more often so I wondered if anyone has any idea what it might be.

The car's had the following done due to slightly rough running and lack of power shortly after we got it.....

PCV filter replaced (it was manky!)
EGR valve removed and thoroughly cleaned
New in-tank fuel pump
New fuel filter

With the increase in limp mode problems, I fitted a replacement (used but much cleaner) intake manifold and EGR blanking adaptor. Same problem again. It seems to happen when the car is up to temperature then switched off for 20mins or so and restarted. It's also happened a couple of times on the motorway, when the car has been up to normal temperature for a while. Not what you need on the motorway really :eek:

I've disconnected the MAF this morning and will see if that makes any difference but open to other ideas....

[Mike Noc]

Try unplugging the LP fuel pressure sensor - it is the plug in top of the fuel filter. If that allows the engine to rev freely the fault is on the fuel low pressure delivery side.

[mgmark]

Thank you. Is that something I would need to do at the time the car plays up? Not something I can just unplug now and leave unplugged?

What could be a likely cause?

[Mike Noc]

Probably better to unplug it when the car is playing up - it may bring on the engine management light.

Don't know how new your car is but if it has an under bonnet LP fuel pump then that could be starting to fail. Did the limp mode start after the in tank pump was replaced? If so then could be a problem with the pipework in the tank.

[mgmark]

The car does have the under bonnet pump. It had been fitted with a new one just before we bought the car probably because the original had died after being overworked due to the in-tank one being dead.

The limp mode thing is a new thing. After fitting the in-tank pump the car ran fine for weeks, possibly even a couple of months, but does seem to have become more regular.

[mgmark]

It's a 2003 cdti auto.

Just been out to it to move it and ended up having to use jump leads as it didn't have enough juice in the battery to fire up. This is the 2nd time that's happened since we got the car. Last time was a few months back though. Could a weak battery cause the imp mode issue? It has been used for more short journeys recently which I know wont help the battery. Until recently, I have been using it for my 65 mile commute so the battery gets chance to be topped up.

[Greeners]

Stick the battery on charge for 24 hours and see what happens

[COLVERT]

It's a 2003 cdti auto.

Just been out to it to move it and ended up having to use jump leads as it didn't have enough juice in the battery to fire up. This is the 2nd time that's happened since we got the car. Last time was a few months back though. Could a weak battery cause the imp mode issue? It has been used for more short journeys recently which I know wont help the battery. Until recently, I have been using it for my 65 mile commute so the battery gets chance to be topped up.


If you have a multi meter, check your battery first thing in the morning before you start up.

Let us know what voltage you get.

[mgmark]

We've been out for most of the day so planning to put the battery on charge in the morning, but will check the voltage before I do.

[mgmark]

The battery is now on charge. The car wouldn't fire up this morning, just dash lights and the usual 'click click click' Checked the voltage and it was just under 12v so will leave it to charge until tomorrow morning and see how it is then

[mgmark]

The battery has now been charged and is giving 13.2v with the car switched off and 14.7v with the car on tickover. I took the car out for 10 mins or so to get it up to temperature and stopped off at the shop for 5 mins. No sign of limp mode but wont take that as the car being fixed. I'll see how it goes over the next few days