[Disco 1 auto Throttle problem]

Last night I removed the multipole connector from the ECU and put it back a few times and can now NOT reproduce the very rough, irregular, throttle position dependant running of the engine. I used the car today and everything seems fine. It is hard to believe that all this could be due to bad contacts. The ECU is in the passenger compartment, not even under the bonnet where one could imagine having much more harsh environmental conditions leading to bad connections.

I will keep the forum informed how long it will last to run correctly.

I seriously start to believe that the manufacturers create more trouble than good with all these sensitive electronics in the cars especially when I think back to my first Discovery 200TDi in 1990 were the only electronics in the car was the radio and most problems were relatively easy to fix.

As promised, here an update on the running of my Disco after the removal and refitting of the multipole connector from the ECU.

Since the 18th of December I have done about 3000 kms without the CEL light coming on or the engine struggling a single moment! So I believe that it was a bad contact. In the circuit for the throttle potentiometer very little current circulates, a bad contact changes the total resistance in the chain or can result in a temporarily open circuit under certain conditions. In the car industry every penny seems to count and good, long lasting connectors are expensive! What car to buy next?

[Disco 1 auto Throttle problem]

Last night I removed the multipole connector from the ECU and put it back a few times and can now NOT reproduce the very rough, irregular, throttle position dependant running of the engine. I used the car today and everything seems fine. It is hard to believe that all this could be due to bad contacts. The ECU is in the passenger compartment, not even under the bonnet where one could imagine having much more harsh environmental conditions leading to bad connections.

I will keep the forum informed how long it will last to run correctly.

I seriously start to believe that the manufacturers create more trouble than good with all these sensitive electronics in the cars especially when I think back to my first Discovery 200TDi in 1990 were the only electronics in the car was the radio and most problems were relatively easy to fix.

[Disco 1 auto Throttle problem]

This weekend I cleaned the battery bodywork/chassis connections. The –Ve cable from the battery connects to the bodywork just behind the battery and then continues to the chassis where it is bolted onto and terminates. Under the same nut as for the bodywork connection are also two lugs with each two thin wires wich disappear into the cabling loom going from there towards the motor just under the injection pump. The motor now behaves even worse, multiple throttle positions were the CEM light comes on and the motor runs very irregular. To be continued ……

[Disco 1 auto Throttle problem]

The error codes my garage got via their test gear are:

-132 Throttle potentiometer, 1) value outside limits, due to a broken wire or short circuit of sensor wires 2) unreal values of the throttle potentiometer compared to those of the idling switch of the butterfly valve

This is why I changed the throttle potentiometer! Though did not change/repaired the problem.

[Disco 1 auto Throttle problem]

I am new to the forum but have read the articles with great interest. I have a 97 Auto Disco showing the same problem. My LR garage in France had and still does not have a solution. The readout of the diagnostic program points at the throttle potentiometer, cooling water temperature and bad wiring. I checked the wiring and see no obvious problem. I have also noticed that the problem seems to be temperature ‘independent’ and did not change the temperature sensor. The obvious one to me seemed the throttle potentiometer and thus changed it. The Bosch part, although still very expensive, was half the price of the LR part. This as more of you have already discovered, did NOT solve the problem. I am now investigating all the various sensors connected to the EDC, Mass Air Flow (MAF), Manifold Absolute Pressure (MAP), Exhaust Gas Recirculation (EGR) etc.

Have any of you more news on the problem?

[Disco 1 auto Throttle problem]

Unlucky - I was hoping you'd fixed it!

Mine is doing it more often now and I seem to be able to make it do it more often as well, Just about every time I drive down ash bank I can get the revs to the right point and make the light come on.

I'm pretty sure there is 2 points at which the light comes on, one around 1200rpm and one higher somewhere round 1650rpm.

I was talking to a mechanic friend the other day who said they had them quite often doing a similar thing (on cars) and all they did was take the top off and pack them with electrical grease and send them on their way, but if you've ruled out the TPS then that shouldn't do anything.

I can't think how the ECU could die at certain points, it just doesn't seem logical that it would wear out, it should really be something mechanical like the TPS. I can't even see that a dodgy connection would only occur at certain points so it shouldn't be the wiring.

If it's not the TPS the only other part I can think of is the fuel pump as I guess it must interpret the readings from the TPS and turn these back into something mechanical to operate the injection pump, I'm guessing if anything it would be that, that is worn.

New fuel injection pumps aren't cheap though although one a 2nd hand one recently sold on ebay for £41 + £20p&p (item number 170169404769)

I don't know if that part of the fuel pump can be cleaned up and I have no idea how it works - just trying to think through what could be at fault