I've spent the past couple weeks doing work on my Disco. Initially I did the option B fix to get rid of the three amigos. It worked like a charm (sorta, more on that below) and I was pretty damned happy with myself.

However, I had also been facing a persistent problem of a high idle (~1500 RPM) only while in park on a cold start -- switching into reverse/drive causes the rpms to settle down to 700-800 range and all is well.

While the amigos are gone, I'm still seeing the high idle, AND getting this intermittent code on my nanocom:

• 20-01 sticking throttle - intermittent

Here's what I did:
-Did the option B fix, that cleared the Amigos -- Most of the time. The ABS warning light hasn't come on at all, but the HDC and TC do sometimes (when I get those two codes)
-Replaced the throttle body heater plate to deal with a small coolant leak.
-Pulled the throttle body. It's spotless, and the valve seems to be moving smoothly -- I replaced its gasket when reinstalling, btw
-Pulled upper intake manifold, ensured it was clean, replaced its gasket
-Replaced valve cover gaskets (they look great inside, no evidence of any coolant which I was worried about because head gaskets...)
-Replaced plugs and wires (NGK iridium and STI/Karlyn 8mm)
-used MAF cleaner on the MAF -- despite following the instructions TO THE LETTER this apparently damaged the MAF, when I had everything back together the SES light came on. I ended up replacing the MAF and the SES went away
-tried an aftermarket TPS, but ended up switching back to the original Bosch because the replacement didn't fix anything, and the wiring connector didn't effectively click into place -- although I had it taped together pretty firmly just to see if that was part of the problem (started a separate thread on that here, and talked to the guy at Rovers North who told me that he's had the same problem with every non-Bosch TPS)
-used carb cleaner on the IAC valve and had a bunch of crap come out of it, carbon buildup, I guess. Put it back in place.
-Looked for any obstructions from the airbox, found nothing, replaced the air filter.
-Reset the ECU adaptive values
-Went through two cans of carb cleaner to try to find a vacuum leak
-sprayed down the throttle body/linkage with carb cleaner and used kroil on it in case it's physically sticking, doesn't seem to be.

So, end result, the amigos are gone (well one of them...), but I'm still seeing the high idle on cold start, I'm getting those codes mentioned above, and I'm occasionally (when the codes are thrown) seeing the HDC warning and TC lights (No ABS warning light).

I'm at a loss.

 

Do you have secondary air? That is typically how nine starts as well and I've been told it has to do with the secondary air set up. I've yet to disable the secondary air to find out though

 

I do have SAI -- California disco.

Funny thing is, I'm almost certain that the cold start high idle started after I had the CPS replaced by a shop -- I'd shot a cold start video some months before.

I told the shop that the idle wasn't a problem before, they took it back in and couldn't find anything wrong with the work they did (assuming they checked the waveform on the CPS and looked for signal & voltage issues.) They couldn't find a root cause and suggested I take it to a local land rover shop. Problem is that the local LR shop is going to be more than an arm and a leg. I'd like to try to get to the bottom of this myself.

 

Been thinking some more about this... I think it's safe to rule out the IAC valve b/c of those codes.

I think I'm going to pull the throttle body off over the weekend, it's looks clean to me, but maybe it is sticking somehow. I'm assuming a brass brush would be safest. Kinda worries me if that is the problem though. I think the part's been completely discontinued, so if the butterfly valve isn't operating correctly, I'll have to roll the dice on a used part from somewhere that might end up being just as bad.

These pics are from when I first had it off.

 

I had one (237k) that developed a little hitch in closing, if you eased off the throttle it would stick at about 8% open. If you snapped it open and shut it would close all the way. Only one I ever had do that. Just buy a used one off ebay or fb marketplace and if it does not work resell it on ebay.

 

Mine was doing the high idle thing a few months ago. Check the baffle on the passenger side valve cover. It can be a bitch to get out without breaking it but it was the culprit in my case.

 

Do the PCV mod and get rid of that baffle entirely.

 

I am not saying anything about the results of buying one from Goldwing Rover... The reason I'm not saying anything is that I don't want to tempt fate 🤣

I will just say this: That's a great suggestion and definitely 100% something that's worth trying.