Injector lift sensor

Johnno · Post by **Johnno** » 06 May 2007, 18:38

I've never been able to solve the sudden loss of power my 2.1 suffers from. It can happen from start-up or even part way through accelleration - or it can be fine for an entire journey! DickieG was able to read the fault code and the lift sensor fault is coming up. I've read some of the previous posts that mention this sensor in order to gain an understanding of what is does. I note that Anders states that the pump will go into emergency mode if the sensor signal is missing. This is what I would have expected.

So, in order to check the effect of the sensor, I disconnected it - with no apparent change in the random nature of the symptom.

I'll check the resistance on the sensor tomorrow, but for the record, what effects should I have experienced with the sensor disconnected?

NiSk · Post by **NiSk** » 07 May 2007, 18:13

On my XM 2.5TD, which had the same problem, the engine ran reasonably OK up to about 2200 rpm, after which it could only be coaxed up higher by easing off on the throttle and taking advantage of downhill slopes. I could usually get it up to about 70 mph, but the annoying thing is that it acts quite normally between tick over and about 1800 rpm and then just refuses to accelerate any further (without the coaxing mentioned above).

My needle lift sensor was burn out (infinite resistance) it should measure around 1000 ohms with a multimeter across the terminal pins.

//NiSk

Johnno · Post by **Johnno** » 07 May 2007, 19:31

Thanks, NiSK. I've checked the resistance - which, as we know, is futile - across the lift sensor and it appears to be open circuit. Not sure why I get the variable symptoms though. Mind you, who knows what the simple electronic brain in the ECU gets up to on these things. I also tried the test of disconnecting the TDC sensor with the result that the engine wouldn't start. I had hoped that the engine would start but that the rev counter would die.

I'm going to check the wire first but if it's not that then a replacement injector. Damn it! That's the second one I've had to do!

AndersDK · Post by **AndersDK** » 07 May 2007, 19:46

Hi John-

The sensor signal is used as the precise injection timing reference for the ECU, which then determines from other conditions where to place (timing wise) the next injection.
If the ECU dont get a reference signal, the ECU will use a stored default value for altering the timing. This is not strictly a "limp home" or "emergency" mode for the pump or ECU.
It would be more correct to say the ECU in this way is 'fault tolerant' to a sensor failure - and thus provides an 'emergency' function.

Never mind : problem found and soon your 2.1TD will have recovered

NiSk · Post by **NiSk** » 07 May 2007, 20:57

I managed to pick one up from a breakers for around £30. Don't forget that all other 2.1 TD12's with the EPIC injection system also fit (Peugeot 406, 506, XM, Xantia; Boxer, Jumpy, Expert vans fitted with the late 2.1 diesel, etc.

//NiSk

Xaccers · Post by **Xaccers** » 08 May 2007, 09:33

My 2.1TD seems to stutter around 3000rpm, and when I first got it, was really gutless.
Could this be the cause?
Would it effect fuel economy?

Post by **CitroJim** » 08 May 2007, 10:44

Xac wrote:My 2.1TD seems to stutter around 3000rpm, and when I first got it, was really gutless.
Could this be the cause?
Would it effect fuel economy?

I did not see much evidence of it yesterday Andy

It was going remarkably well from where I was sitting!

Try unplugging it and see what difference is made to the running. It should be very significant.

The other things that affect timing are the Coolant Temperature Sensor (a well known trouble spot in Petrol XU engines) and the TDC sensor although the latter normally gives itself away by stopping the rev. counter...

The timing being out will quite dramatically affect the fuel economy.

Xaccers · Post by **Xaccers** » 08 May 2007, 16:24

She does fly, but now and again goes back to being a bit sluggish, and there's definitely some hesitation around 3000rpm.
Will fill up and work out the fuel economy.