Hello after throwing a code for the TPS I decided to order a new one, and after getting it, and installing I noticed my Disco wouldn't idle below 2k no matter cold or warm. So I did some searching and found a lot of info about a stored code that can only be cleared by dealer/testbook, or some who had luck with the age ol disconnect the battery for a bit then connect and it worked fine. I tried the battery disconnect first for 10 min, then 30, then overnight, and this changed nothing, fire it up and it still runs at 2k. I am thinking that previous owner ran into the issue as the TPS that has been in it until now appears to be modified slightly. If I have the old one in and tightened down the way it was then the engine will idle fine, but even with the old one if it's adjusted to where it should be without the modification that someone did then it goes back to running at 2k. Mostly I am just wanting to get peoples thoughts and suggestions as I am pretty sure I will have to take it to a dealer, but sadly that is a 240 mile one way trip to the other end of Oregon, and in summer . Any assistance would be greatly appreciated, I have included pictures of the old and new TPS, and the position of where it mounts on the butterfly without the sensor on there. The last pictures are a more just in case something might be slightly off there, but it doesn't seem off to me. Thank you very much for reading and I hope you all have a great day/night depending on when you read this. Also sorry for the size of the images, don't always remember to reduce the images after taking pictures of things other than car stuff :P

Old modified one on the left

Old modified one on the bottom

 

My '96 did that and I hogged out the holes (like on your old one) to reduce the signal value (throttle closed direction, less initial movement of the pot). High revs happen when the value of the signal for throttle position is greater than the stored zero position value (typically around 12%). If the value is less than the stored value, there is no problem, so the hogging does not need to be precise.

Later, I got a new TPS and reset the stored value using the GEMs Lite app on my tablet (free or low cost download), paired with a bluetooth OBD dongle. The GEMs app has a function to Reset Adaptive Values. If you reset with Key On Engine Off, then it will idle normally when started.

Hogging out the holes is easy and low cost and does not cause any engine problems. Using the GEMs app is simple and clean, and useful for other maintenance functions. Your choice.

 

For whatever reason someone hogged out that hole to compensate for something. In turn the ECU 'learned' the new position as default. Now, with a new TPS, the default the ECU learned is incorrect.

As John wrote, the best way to 'solve' it is to re-set the adaptive values of the ECU setting it back to 'factory default'. Robertf created an app that runs on Android to do this. All that is required is a dongle for the OBD port to communicate with the handset or tablet.

 

Sorry for the delay, yesterday was rather hectic. Also want to say thank you John, and Walt for the replies, and the information. A OBDII dongle is much cheaper than driving all the way to the north end of Oregon, and I don't have to deal with Portland traffic :P. Now to look into the dongles more as the brief looking I did late last night I found a lot of different ones, and now just need to find a decent one. Which now I think of it is also much cheaper than a testbook, and it will work for the other rigs I have as well, but one day I will get a testbook..well maybe if my brain will ever justify spending that much :P. Will keep you all informed on progress. Hope you have a good one, and it's not getting way too warm where you are.

 

Read through these first...

https://landroverforums.com/forum/di...33/#post647370

https://discoweb.org/index.php?threa...5/post-1048864

 

The OBD Link LX has served me well, and pairs to the tablet or phone with the push of a button. The indicator lights are useful. Works well with the Torque app to read real time O2 sensors and fuel trims. Also works with the GEMs app.
Price is up near $90 now. Cheap ebay dongles are available which I used when I didn't have any money, but then stopped working after some time.

The software app is actually more important than the hardware. I try to stick with time tested brands.

 

Thank you both for the very useful information, and experience with the dongle, I was trying to decide between the OBD Link LX, and the Anyscan A30M, and after reading through the links Walt posted I saw a lot of people are using the LX. I probably will be going with it as others like it, and it's only around 90 bucks rather than the anywhere between 150-200 that the A30M runs, depending on where you are getting it from. I do like the idea of being able to do it with a laptop also, but sadly the only laptop I have access to right now is a older windows 8 laptop that is a bit obstinate about when it wants to work as it needs a new hdd.

So I decided to go with the OBD Link LX, as I still haven't heard back from the Anyscan A30M people, I emailed a bunch of people asking if they would work with the Discos, as well as my 03 Pathfinder. As some of the dongles I was looking at had issues with older cars past just reading codes. Will update once it arrives.

 

So wanted to post a update. Got the OBD Link LX, and the GEMS Lite app, and ran the adaptive reset option. It reset the values to 0, and then started it up as engine was still cold, it idled still at round 2k so decided I would take it for a short 1/2 mile round trip drive for a test. Engine had warmed by the time I was half way down the road I live on, and at the stop sign it seemed to be idling fine. Though the RPM was dropping a little slower when clutch was pushed in so I adjusted the accelerator cable slightly and it acted fine, but this time the idle was a little lower. Not stalling lower or barely running, between the mark under 1k and the half mark from 0, but got it back and seemed fine. This was around 11am today, so let the engine cool down, and just a few minutes ago went out to try it again, and it's back to idle at 2k, let it idle there for a bit, and even tried moving it back and forth about 20 feet, but idle stayed at 2k. So I am a bit lost at this point, and I could try the PC/laptop method, but figured I would give a update and see if anyone had any thoughts.

 

With engine off, key in position II

Engine running, but not warmed up

 

Double check that the TPS rotating part is on the correct side of the throttle tab. Use a screwdriver to determine the correct side, then needs to be rotated slightly while placing into position, then rotate against the spring to align the screw holes. Check real time TPS signal % using the Torque app (key on engine off) pressing the gas pedal. Mine goes from around 10 to 85%.

Have you checked the throttle plate position? Full closed the plate distance to top and bottom edges should be equal. There is an adjustment screw underneath if the dimensions are not equal, or loosen the throttle cable if it is too tight (it should be slack). The setting might have been thrown off when you adjusted the cable, so needs to Reset Adaptive Values again. Reason I ask is the TPS Close Throttle value looks high. Probably should be closer to 0.5 - 0.6 V. If the throttle plate is full closed with equal dimensions, at this point I would probably hog out the holes to reduce the signal , adjust to 0.5 or 0.6 V, then reset adaptive values again. That is probably why the original was hogged out in the first place.

Sounds like you are very close to the solution. Hang in there! If idle is too low when warm, do not adjust the accelerator cable (or TPS). That indicates a possible fault with the IACV, bypass passage clog, or base idle mis-adjustment. Use the Torque app to monitor RPMs more precisely, should be near 650 - 700 when warm. The ECU controls RPM by modulating the IACV, not the throttle.