Problems with idling speed on 1998Xdi

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Landy1998

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13
Since a couple of weeks I am facing problems with my iddling speed. It sometimes stays up at 1250rpm and only after releasing the break pedal, it falls down to 750 to 800rpm. Every know and then, the iddling speed goes up to a maximum of 3000rpm without any interfeerence. I also notice, that the between shifting gears, the engine rpm does not fall back to minimum quick enough.
According to the service station, the accelerator potentiometer (Part # SLD100061) is faulty and gives the wrong output voltage. However, I took the Bosch Potentimeter apart and checked all the contacts but could not discover any wear out or other abnormalities.

Due to the enormous price of the part (approx. AUD 1,200 without labour), I am very reluctant to change it before having checked all the other possibilities.

Did anyone experience similar problems with her/his Freely?

Thanks for your comments and best regards from down under

Peter
 
Hi is the Penotometer the thing which screws into the plenum ? same as Range Rover/etc ?

If so why pay $1200 just get yourselve a multimeter from any auto store find the figures for you're car (haynes manual will do or any good mechanic)

All you have to do is move the thing till you get the correct readings.

Charlotte
 
Hi Charlotte

Thanks for the tip, I’ve already measured the resistance of the potentiometer and couldn't find anything unusual. Do you know, whether the accelerator percentage is calculated only on the base of the potentiometer readings or are there other values taken into consideration?

Thanks

Peter
 
It's a multitudal calculation the ECU receives info from the pot then adjusts the fuel mix to the meter the ECU receives the info back so the cycle goes on and on.

If either of these components are faulty or mall adjusted then the cycle will be interupted.

is teh pot a small round black thing connected to the idle flap somehow ? It may be slightly larger but will do the same job. How old is the car because the wires on older vehicles can be almost vulcanised so even though the wires appear intact they may infact be broken somewhere in the casing.

Can you get the replacement part aftermarket or scrap jard (junk yard)


Do you have anywhere which can get the ECU's checked there may be more than one say one for the engine one for the fuel one for the extras

I prefer vehicles without ECU's just getting over an Opel with an ECU in the auto box which has failed and I'm being quoted £800 +Labour @£79ph +VAT @17.5%

Although my Range Rover has one ECU which controls everything.

Have you tried taking the connectors off the ECU/s and cleaning them with contact cleaner also try the Fuel overrun. In short yes everything is linked in some manner
 
Hi Charlotte

Thanks again for the very competent reply. I had the car in service and checked via the computer analysing device, which showed that the output voltage of the potentiometer is constant but the calculated value is playing up and down.

Another phenomenum I discovered is, whenever I have to break (i.e. in front of a traffic light) the idling rpm goes only back to about 1250rpm and as soon as I release the break it goes down to about 800rpm. Additionaly, the playing up seems worse after refulling.

I have also removed the potentiometer block reassembled it and checked the connection, without any improvement.

Unfortunately, I can't get a 2nd hand part here in Australia and the original Landrover spare part (#SLD100061) which comes from BOSCH can only be sourced at arround AUD 1,200. However, I could get the same part shipped out from the UK for about AUD 500 (GBP 195). But before I am going to order the part, I absolutely wanna exclude all other possible reasons for faillure.

But you mentined also that one of the parts could be mall adjusted, can you tell me more where and how to adjust them?

Which other parts/sensors are involved in the calculation of the accelerator percentage?

Thanks for your great support ;)

Peter
 
Has anyone experienced similar problems and figured out it has something to do with the diesel supply?
 
I don't think its the deisel supply, unless my 1999 1.8 petrol has had an engine change overnight. I have the same problem with idling speed, it is going back to the garage next week, fingers crossed (only had it a week). Reminds me of a problem I had with a Vauxhall Vectra, turned out to be the Idle air control valve on that, but doubt its that simple for a landy.
 
Thanks boys and girls for your great support...

All your answers fit into the symptons of my case, however I am still missing the final clue. Especially in light of the fact, that the iddling speed behavious seems to be somehow related to the level of diesel in the tank. The higher the level, the less playing up and down of the iddling speed. Therefore, I appreciate every little bit of information, that could help to put the puzzle together and get the correct analysis of the problem.

Thanks and keep posting!!!

Peter
 
Could be a problem of fuelpump capacity than, if the tank is full or almost full the main fuelpump has almost nothing to do because of the downforce of the fuel in the tank pushing the fuel down the line towards the engine and the 2nd fuelpump located next to the engine can coope to fill enough to have the engine run more or less normal, when the tank becomes emptier and practically no more downforce and the main fuelpump is not able to give full capacity, also the 2nd (smaller) fuelpump in the enginebay can not coope with it and the idling becomes more instable. Not sure whether an Xedi has 2 fuelpumps but I know the Td4 has. (When they replaced my faulty fuelpump, located in the tank, the headmechanic told me to try to fill up the tank when still at least 1/4 fuel in it, this to avoid dirt is sucked up and secondly to have a certain downforce in the system to enlighten the task of the smaller pump in the enginebay. He mentioned that several people running their car on moderate revs/speed all the time and filling up the fuel when the tank still half full, very often don't even notice their fuelpump is gone as they have no problem because of the downforce in the tank which is enough to push the fuel down the line and with the help of that secondary pump near the engine things run perfect.)
Of course don't know whether this applies to your problem but I thought it might be related and worth to be mentioned? Good luck.
 
Hi Will

Thanks for the detailed information, I'll follow this path and check the proper functionning of the fuel pumps.

Thanks for the hint and best regards
 
Hi Will

The Problem doesn't look like beeing related to the fuel pump. What do you think of the possible influence of the MAP sensor. As I learned in an other Forum, a malfunction of the sensor could have a negative influence on the computer.

Peter
 
Hi Peter,

Sorry but my only experience is with the Td4, not the Xedi. I was just thinking along the path I went through with my car and the faulty MAF did not result in idling speed problems, as for the faulty fuelpump, there was no idling at all anymore there ..:D :D
Sorry I can't be more helpful, I hope someone else on the forum will come to your rescue. Good luck anyway and take care.
 
the xedi only has the high pressure pump pre injectors, check for split hoses concerning brakes/tickover because there are some conneting vacuum pipes for assisted braking and if split will increase tickover,tiga
 
Hi Guys and Gals

I think I solved the mistery. It was the MAP sensor that screwed up and feeded the bordcomputer with misleading information about the ambient as well as the actual Mainfold Airinlet Pressure.

Land1998
 
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