Still fighting high idle.....
 

I am still fighting high idle issues on my 98 D1. I replaced the IACV a while back and it idled fine for a few days then it was back to 2000 rpm on a dead cold start and a 1500 idle on a hot start. However on a first cold start (morning) it will idle at 2000 but once it warms up it drops to 1000 but if I shut it off and restart its at 1500. If I shut it off and leave it for 30 minutes it will idle at 500 and with a blip of the throttle it will idle at 750 and slowly climb to 1000...Agian once i shut it off and start it its back at 1500. I had it on a Land Rover T4 scanner and temp through the scanner reads fine maybe a bit cold at about 49 degrees C (120 degrees F) after sitting for 30 minutes on a cold day but the throttle position was at 11.4%. I would think that the throttle position % should be a 0% at idle however it is throwing no codes for a TPS. I also tried to get it on an Autologic scanner but it would not talk to the ECU no matter how hard I tried. I am at a loss here I am worried about my transmission because I either hold it while its at high idle at a stop or have to neutral drop it which isnt good. Let me know what yall think!

if you havent already - start here
https://landroverforums.com/forum/di...acement-83233/

I replaced my IACV and cleaned with no avail - software did the trick for me

I am going to give that a try, thanks for the link.

After you’ve cleaned everything; ie decarbed your intake, sea foam, etc and checked for vacuum leaks, you can try disconnecting your bat to reset the ECM.

I’m betting you got a vacuum leak though...

I chased this for some time and it turned out to be a vacuum leak back at the gas tank.

Check this thread out: https://landroverforums.com/forum/di...estions-83496/

Everything looks good and is clean, I couldn't find any leaks and I left the battery unhooked overnight and am still getting the same results. Its almost like its an electrical issue or the ECU thinks that the motor is super cold but the scanner showed engine temp at like 120 so that doesn't make any sense.

any progress on this?.........some of these advanced evap trucks have an issue with the fuel tank pressure sensor failing( or the wiring to it)...the tps and iacv share the power feed with it......if the pressure sensor fails ....you get no code for it....but it messes with the tps and iacv....and often produces a high idle and / or rough running condition...you can roll up the rear carpet and unplug the sensor on top of the fuel pump assy to see if that changes anything.....personal experience

Had the same issue when I owned a D1. I tried everything, even the value reset, nothing worked. What I ended up doing was drilling two holes next to the existing ones on the TPS so I could manually adjust it to lower the idle. It worked quite well, never messed with it again. Worth a shot if nothing else works.

No progress yet. I am waiting for my OBDII to usb thing to come in so I can try what Whiskey referred me too. I'll try the tank pressure thing this weekend. I've kinda got it down as far as dealing with the idle. First start of the day it will idle perfect after its warmed up and then after that i just shut it off at red lights and it eventually it will idle fine. But, its still broken and I'm still thinking its something electrical. I am kinda thinking it has something to do with the TPS because the T4 scanner was showing it was open 11.4% at closed throttle which was verified at the throttle body. However I can't find what the values should be at idle for the TPS.

Update. Still waiting on stuff to come in but I decided to mess around and see if I could change anything. I unplugged the IACV, TPS, MAF, inlet air temp sensor, coolant temp sensor and started the truck. I would let the truck idle for about a minute and then shut it off. I did this about 10 times and the truck ran like crap which I assumed it would. No CEL light came on or anything during that time. Then I plugged everything in and started the truck and it idled right at 700 RPM I ran errands for about 2 hours and It idled perfectly. The next day I went out to start the truck and it was back to having a high idle however it was only at 1500 RPM compared to the 2000 RPM it used to idle at during the first start of the day. Still at a loss here.