Derek Martin

My Disco 1 300tdi had a huge shudder a couple of times since I had it, and in each case it was due to the universal joint taking the drive from the transfer box to the front axle being shot (the transfer box end of the prop). Try moving it in either direction and look for play in the joint.

I drove the Disco on Sunday night, and my CEL light problem was happening again (my wife normally drives it, and doesn;t always tell me if theproblem is there, to be honest I don't think she even notices it anymore!), I pulled the conector off the Airflow mass sensor and replaced it and the problem went away for the trip home, I haven't driven it since, to see how it is now. Mine could be just a dodgy contact as well, or maybe even a couple of dodgy contacts as the problem has gone away when I pulled the ECU connector, like you have, but it still keeps coming back.

Sorry it's not a problem I've had with mine (yet!). I don't suppose it had any biodiesel run through it has it?, it if has maybe that would be effect the pump seals etc? I'm considering running mine on Bio so I'd be interested in any problems. I've run a tank of 50/50 diesel/bio through my peugeot 205 and been quiet impressed so far (now smells like a chip shop driving past!), but the supplier near fessy park has run out, so I won't get chance to try it until later (I'm trying making a test batch myself over Christmas, should be fun!). I'm surprised that the engine will run without the lift pump, maybe once the fuel lines are full the main injection pump can pull it from the tank? can you tell if this has had any effect on the CEL problem yet?. With the pump off the car can you operate it by hand and get it to pump fuel through?, or maybe force fuel through under pressure to clean it out? I seem to remember reading in a forum (maybe here, not sure) that operating the lever by hand can damage the pump. Mine is still running ok! Have a good Christmas etc. Derek.

The drain plug on my sedimenter was also broken off, however its very easy (if messy) to get it apart, the bolt on the top is 11mm, I just felt with my hand to find it, (you wont see it by eye), it undid very easily. The sedimenter casing is in two parts with a rubber seal between its top/housing and between each section, once the bolt is out, just pull it away at one side, and get ready to catch the fuel in something, especially when the two sections come apart, it runs up your arm very nicely!. Mine had a bit of carp in it, but since I first cleaned it out, there has been very little in there. Derek.

I suppose the engine temperature gauge is ok?, I use my Disco to tow a caravan, and on a return trip from Cornwall had a very bad time with the engine overheating. I eventually traced it to the radiator (most of the vanes on the grill side of the side had collapsed), every time I went up a hill the engine overheated very rapidly, and the power dropped off to the point where I was doing 20 mph uphill on the Motorway (everybody else was very pleased with me!). as soon as I reached a flat or downhill section, the power picked up again as the temperature dropped. I think the ECU has an overheating mode, where it just drops the throttle setting off, making it impossible for you to go any faster. Once I changed the rad, the temperature never changes. Still no problem with the throttle since I unplugged/plugged the MAF connector, it will be back though! Derek.

I have never had the CEL staying on like that, I have thought that the best thing that could happen would be a total failure of whatever is causing it, at least I might stand a chance of finding it!. (not very helpful at the time of the breakdown I know). Seems similar to ours in that messing with the cables etc causes it to run ok for a while, then back to the normal problem. If the CEL problem is repeatable again, try pulling the connector from the MAF, my wife say our has run with no problem since I pulled the connector last Saturday, rev'd the engine (problem went away) and reconnected it again, how long for though?.

I was wondering why the TPS would need to have an idle switch, is it just on/off when the pedal is pressed or not pressed?, i.e. it would signal the ECU to put the engine into idle mode rather than read the pedal position from other circuit?. Derek.

When I heard the click on my car I had a look at my haynes manual at what relays were in the driver footwell below the ECU. and one of them is the Engine load control relay, the wiring diagram shows this as being to conected to the +ve battery terminal via fuse, then 2 supplies one going to the going to the ecu pin 15, and the other to ECU pins 16, 17, EGR, Fuel pump, fuel injector assembly, and data link conector. Does this just control the power to all these parts?, i.e. turns them on when the ignition is on?, if so why would it click at approx 2000 rpm? . I couldn't be certain which relay it was, at the time I was operating the pedal by hand, a keeping the probes on the relevant pins, and the ECU got in the way of me putting my ear ot hand against the relays!. Derek.

I took my voltages between pins 33 and 37, so that may explain the difference?. I would have thought the drop in voltage when the problem occurs is interesting, and may suggest the TPS is at fault?. I still have my original TPS, so if you want to try it, let me know, we could just plug it in under the bonnet., and move it by hand. I went out to look at mine again, this morning, but found it wasn't starting very well, so I ended up replacing a couple of Glow plugs, beam ends hadn't got any unfortunately, so had to get them elsewhere, very convenient having a part supplier only up the road! I remembered that Guy mentioned the MAF, the car was having the problem as normal, I removed the connector on the MAF, and the engine revved without problem, I put the connector back on, and the engine has been fine for the rest of the day. This is what happened before when I removed the connector, but I showed my wife what to do, and she said it stopped curing the problem after a few days. I'll try and repeat your tests in the week, and post the results. Glad you thought you could hear the click when the light comes on, I found it difficult to be sure, maybe there is a miniature relay in the ECU, I was'nt convinced it wasn't one of the other relays by the ECU.

I've been so many 'it could be this or that' scenarios that I've lost count, at one time I thought it might be the Air Mass Sensor. I found that at one stage disconnecting that appeared to make the problem go away for short a time (maybe a day or so). Disconnecting the plug didn't put the CEL light on at all, I have read somewhere that the ECU uses a default calculation if that sensor goes u/s?. I found after a few tests that it did not necessarily always cure the problem, so I gave up on that line of solution, until I send it into the Bosch specialist. The only other alternative is the replace bits and see it goes away solution, which could be very expensive for a car not worth that much anyway, that's why I bought the replacement ECU when I saw it at a reasonable price. I'll try and have another go at reading the voltages etc on the pins you mentioned. Thanks for the advice, all help gratefully received! Derek.

No, its actually pretty easy to get it out, but a little fiddly. I remove the cover from above the pedals (3 plastic push in fixings), then remove the plug for the laptop used to read the ecu etc, and get the cover out of the way (i've left mine off at the moment to allow me to get the ecu and wiring etc easily). Then remove the plastic panel by the A column to the right of the accelerator pedal(two plastic fixings), get that out of the way. The ECU is located to behind and above the where the panel was. The connector has a retaining clip, you just pull that down, then pull the plug down at the end facing you, the far end is hooked under clip, and will release when you have got the plug a fair way down. The ecu is held in position by two plastic nuts at the end nearest you, these are 10mm, I used a long socket and turned it by hand to remove them, the ecu can then be removed by pulling it off the two threads, and sliding it down to release a catch at the rear, (its not fixed there, just pushed over another pin that fits in a slot on the rear of the ecu. To get access to the wiring, I removed the single screw on the plug to remove th eouter casing, and I could then reach the pins, I then pushed the plug into the ecu and could read the voltages with the engine running. I never tried to reproduce the problem with the engine running in drive but not moving, as I could do it with the car moving, I assumed it would be the same , I'll give it a go over the weekend. Derek.

Guy. I already posted the voltage on mine with and without the CEL light on. As I said before I used a digital multimeter, and could not see any variation in the voltage other than the expected change with throttle movement i.e. no sudden drop or increase at the problem position. I have an older needle type multimeter I could use, but I don't have access to an oscilloscope etc. Derek.

I'll be about this all this weekend, so if you need any help locating it, I think I posted my telephone number earlier, so give me call. Derek.

Guy, glad to have you on board with the same problem, I put my multimeter readings on an earlier post on this topic, but I did use a digital multimeter, which I have been told average out the readings, so for this problem where the throttle position at which it occurs is so specific, it may not be capable of showing the voltage dip, but there was no change in voltage during repeated reproductions of the problem My disco is still suffering intermittently from this problem(see original posts), since my last post I have again attempted to check out the wiring, I still have a suspicion that movement of the wiring loom near the ecu can cause it go a way for a period, but this (along with everything else I try) appears to not be consistently repeatable. I have still not got round to sending the car in to get the replacement ecu fitted to rule that out of the problem. (If anyone knows where I can get it recoded for less than £50 in the Stoke-On-Trent area I'd be very grateful if they could pass on the contact details) I originally thought the problem occurred more often during periods of hot weather, but since it got worse, the temperature appears to have no affect on it. I have recently had some periods where the engine has run very roughly at the points in the rev range where it generally cuts back to tickover(1600 or 2000) and puts the check engine light on, but on these occasions the light has not come on, and the revs stay around the same rpm. I wonder if this could be a separate problem, or maybe just a change to original problem? I have had all the same suspicions, i.e. position at which the TPS must spend most of it's time, engine vibration at certain rev ranges showing up wiring problems, engine speed sensor, etc, but I am pretty disheartened about finding the cause of the problem, with so many people suffering from what appears to be a similar problem, somebody out there must have found and cured it.

As I expecting, the problem has now returned, it is still happening at around 2000rpm (higher than it was originally), I don't suppose something specific happens to the engine about that rpm that may cause the problem (maybe turbo related?). I will get the replacement ECU coded up and see how that goes, I'm going to take it to the Bosch specialist and get them to investigate the cause at the same time if the ECU does not fix it.