300TDi engine speed sensor

Having some problems with the Disco (96 Auto). Had a lot of smoke last year for which the suggestion on this forum was made that it was a pipe between the turbo and intercooler which it was - problem solved.

A few months ago it seemed to be smoking a little - especially hard acceleration (or should that be a lot).

Check the hoses and they were fine. Took it to a specialist who hooked it up to his diagnostic box and it showed that the engine speed sensor had registered as faulty at some time (I have owned it for nearly 100,000 miles from about 65,000 miles). He reset it and we went for a test run - still smoking. He then checked timing etc etc but everything fine.

When I left I noticed that the smoking had stopped and thought it had been cured - but no such luck.

I therefore decided that it might be the speed sensor. If you have not changed one before, the fun begins. It is not located where shown in the manual. I managed to undo the bolt securing it but could not really get at it. However, from underneath I could get at it with a blunt screwdriver and gently tapped it and out it came - or as I was to discover the top had broken off leaving the body in the bellhousing. At that point my neighbour told me that he used to work on Citroens and they always broke off.

The result was the 'check engine' light being on (it had not been previously) and running very roughly - so was the engine sensor slightly faulty or ok but had registered a fault once but was now OK.

I decided that I needed to remove the engine mounts and tip the engine so that the front was lower giving me more and better access to drill it out. So I set to work last weekend. Trying to get access to the bolts holding the mounting plate on the engine is fun and I gave up last Sunday as it was lashing it down. The problem is the diff on one side and the exhaust and oil pipes on the other. I have resolved that I will need to undo and move the exhaust pipe to try to get access - am I right that unless you have the vehicle very high you cannot get the exhaust out and also drain the box and remove the pipes.

I would be grateful for any tips on getting better access - and if you have done the job how did you do it. I do not wish to take the transmission out.

Also any ideas on what the problem is once I find out it is not the sensor causing it (note the pessimism).

Sorry about the long post - but any help welcome.

Paul

Replacing the crank sensor was not going to fix it,now its broken the engine Ecu will default to using the signal on the needle lift sensor on number 4 injector.Usually this results in a higher idle speed,(its not as accurate as the crank sensor) rough running and the CEL on.
So your smoke issue is more likely to be worn injectors,slack timing belt,incorrect boost sensor readings, air flow meter readings or the EGR valve stuck open.

As far as i know you don't have to lift the disco in the air to gain access.
I replaced my exhaust mid sec and back box, when it was grounded, and when i was under there, i was having a look around like you do!!!! and it looked pretty easy to get at the box to drain it, with out lifting it aswell, but may need to be lifted a little for abit more clearance with trolleyjack!

Eightnavee thanks for having faith in my pessimism

Hindsight is wonderful - if only I had just unplugged it first but then again I would have been thinking that as it showed on the diagnostics as a fault then it may not be functioning quite correctly so replace it. No other faults were showing.

I assume that the other sensors that you suggest would not show up as a fault. Of all your suggestions, which order would you tackle them in - it seems to me that I will need to employ a process of elimination or is there a way of checking first?

Many thanks for your help.

JAC I am talking about the downpipe from the mainfold and the cat not the middle and back box. And yes, I had been working on it unraised but eventually put it on to stands to give a little more elbow room plus I was working on it outside last Sunday and it was lashing down and I thought a mains lead light would be a little dangerous! Eventually gave up after less than an hour absolutely soaked.

Thanks for your help

All of the sensors can be monitored via Testbook,best done whilst driving.Other than that an oscilliscope is really the only answer.

Dear trog!

How did you solve the problem with engine speed sensor?

I have the same issue. And don`t know how to replace the sensor.

Taisto

Taisto

What fun!!!!

Firstly, why I was replacing the sensor - I had taken it to an independent specialist who ran all the diagnostics and concluded that the only error that had been recorded was that the engine speed sensor had gone faulty at one time. They carried out tests, such as checking timing etc.

I therefore decided to replace the sensor.

The first problem was that the official workshop manual shows it in the wrong place - as you look in the engine bay, it is on the bellhousing, left hand side at about 10 / 11 o'clock.

The first problem was getting at the allen screw holding it in place. I achieved this by cutting away the inuslation on the bulkhead and using a ball ended allen key undid the screw.

I decided that the only way to remove it was from underneath using a very blunt screwdriver. I placed this against the head of the sensor and knocked the screwdriver with a small hammer and out it came - or so I thought. What had happened was that the head broke off, leaving the body in the bellhousing.

So to try to get access. I eventually removed the engine supports, radiator, fan etc and dropped the engine down onto the crosstube and slewed it over th the near side of the vehicle.

Using a flexible shaft I then tried drilling it out. However, there seemes to be a magnet or something very hard inside and, after numerous attempts I had to admit defeat.

Clearly either the engine had to come out or the box come off.

Now, a Disco is quite a high vehicle and an ordinary engine hoist was out of the question and the box too heavy to remove without specialist equipment so concluded I had to give this to a garage to do.

I contacted another independent specialist on the south coast who, when I told him of the symptoms and why I was replacing the sensor said 'its probably the egr.

I had the vehicle transported down to him.

They had a little difficulty removing the box as, due to my centre punching the part broken off etc it had driven it down so that it was in contact with the flywheel and torque convertor so they could not remove the box and convertor together.

They replaced the sensor with the new one that I bought - no difference. They then inserted an egr blanking plate (£4) and low and behold the smoking was cured.

I realise that the above may have horrified you but it is most certainly not an easy job. They did lubricate the new sensor well so perhaps if mine ever has to come out again maybe it will come out easily but who knows.

It proved quite expensive - especially as I had to have the Disco transported.

I do not know whether you are trying with a manual vehicle and whether that might be any easier.

At the end of the day if I needed to do it again I would probably find the cheapest place that would take off the box and put it back on and get them to do the job.

I am also extremely annoyed at the first so called independent specialist that I went to for not knowing about the EGR fix. If I had gone to the second first I would probably have saved a huge chunk of money (including the £80 for the sensor) and time and frustration.

I hope this 'helps'.

If you want to chat about this then provide me with a contact number.

Paul

As a little PS the auto box has now decided to occassionally slip in 2nd - still it has done 173000 miles and was fine until now. Happened under 2 weeks before I was due to go down to southern France. Had quotes of between £1,250 and £1,900 for a recon box to be fitted but none could do it in the time. My dilema is whether to try to sell it as it is or go for the cheaapest recon option and then sell it as I had to buy another vehicle so that we could make our trip.

OK, all this I imagined when I started to seek, where this sensor actually locates.
But did the CE light stop coming on after they changed the sensor?
And as I realise, if started from taking the automatic gearbox off first, the procedure should be less painful?

Also - what the heck is EGR and egr blanking plate, I just don`t get it in english...

If you are taking the gearbox off then no problem - in fact probably the best way of doing it. That will guarantee that the sensor will just fall out!

It would be possible to do it in situ IF you knew that it would come out easily but it would be fiddly.

My CEL only came on when starting the car. Having broken the top off the engine then ran very roughly - perhaps the thing to do unless you know 100% that the sensor is no good is to disconnect it (connector located at the back of the engine up from the sensor (beware there are two connectors) and see if the car runs just the same of if it is fairly rough then the sensor might be OK.

The EGR - Exhaust Gas Recirculation valve under certain conditions allows exhaust gases to be readmitted to the engine for the gases to be more fully burnt. The valve only operates under certain conditions. Sometimes it gets stuck open - which mine had, which had the effect of under certain conditions, mainly when putting the throttle down for black smoke to be emitted. The car will run quite happily without it - though emissions might go up slightly under certain conditions but fuel consumption might reduce. Rather than buy a new one a small plate can be used to blank off the aperture that allows the exhaust gases back into the conbustion chamber.

Blanking off mine made no difference to the emissions test for the annual vehicle inspection.

Indeed some will advise blanking it off even if it is working for better performance.

Taisto said:

OK, all this I imagined when I started to seek, where this sensor actually locates.
But did the CE light stop coming on after they changed the sensor?
And as I realise, if started from taking the automatic gearbox off first, the procedure should be less painful?

Also - what the heck is EGR and egr blanking plate, I just don`t get it in english...

Click to expand...

Would that be queens english or americanised slang english?

EGR is the Exhaust Gas Recirculator. and it does what it says. You can buy a plate to blank this off and then it doesn't Apparently it make a big difference to the smooth running and performance.

Great that there are people around!

I have found garage to do the job, so I try to earn some for the "most billing piece of plastic" so far. Think it would be wise to change gearbox gaskets instead.

Best to manage vehicles which are not Toyotas

Taisto
______________________________________________
The world runs like Discoball!