I've read so much on this topic I'm blurry eyed. Most on the info regarding this problem is when the stepper motor is replaced. Changing the ECU when you change the stepper motor. I get that, but I didn't change anything, I just cleaned it with carb cleaner! I thought maybe driving it some would help. If anything it's getting worse. My cold idle start up is now almost 1500 rpm. (up from yesterday's 1000-1200)

Can't seem to find any info on adjusting the idle on this model. Some say don't mess with the base idle some say they did.

Sprayed all the linkage down with carb cleaner. Tightened to throttle cable slightly that only speed it up even more so slackened that back off to wear it was. Can't find any obvious vacum leaks. Engine is running super smooth.

Is the only fix taking it into shop to put on scanner? Logic says that shouldn't be necessary since I didn't change anything.

 

I could be wrong but I didn't think the 3.9 could be hooked up to a scanner. What you're referring to is resetting the adaptive values and I don't think there is a process(or need?) for doing so on pre-OBDII trucks.

 

Have you checked for a vacuum leak?

 

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Can't seem to find any info on adjusting the idle on this model. Some say don't mess with the base idle some say they did.

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Imediately I want to say I have little knowledge of this, but the best explanation I have received is that worn contacts on the Throttle Position Sensor most likely is the cause of this and that a new TPS will eliminate this issue as well as short term future problems with smooth acelleration.

Just another input as it may have value in this instance.

 

TPS for 95 Disco are $350-500+! Ouch! Does anyone know how to test to see if in fact this is the culprit? And would buying a used one be prudent?

On the other hand the fact that it was idling at 750 before I cleaned the stepper motor would indicate the TPS is fine?

I'm wondering if it may be a vacum leak I haven't found. But again why would it idle correctly before cleaning? Makes no sense to me. The fact that it would stall sometimes at a stop sign before the cleaning. That sounds like it was starving for air and/or fuel?

 

I really seem to remember tps or IACV on those being adjustable, kept being told to do it on mine when idle was high till I kept saying mine was obd2

Did you try loosening the TPS see if it is egged for adjustment, would only be slight

Any chance you forgot the gasket on reinstall of TPS? Or turned the TPS on accident cleaning it?

I would not mess with the base idle screw will only make things worse imo

Did the ignition timing get knocked off ?

 

According to RAVE TPS is not adjustable and does not loose it setting when worn. Pretty certain I didn't uninstall TPS. Timing is one thing I thought of but if timing was off wouldn't the engine not run smoothly?

This afternoon idle is up to 1750 around 1100 under load. Getting worse. I wonder if I damaged the IACV, seems pretty sturdy unit. I sprayed alot of carb cleaner in it and cleaned to crevice out with a small brush.

 

Talked to my mechanic this morning. Sounds like vacum leak. So I guess Ill spend the day looking for leaks. Having the engine steam cleaned first. Nothing to do with problem but maybe it will make it easier to find leak.

 

What about this?

https://landroverforums.com/forum/di...acement-33384/

 

ok, think I found problem, maybe. If I take off vac line from IACV and put my finger on nipple of IAVC it runs idle up higher. Indicates vac leak at that line? Replaced hose with new one. Maybe brought it down a tiny bit but still idles at 1200 warm engine. I beginning to wonder if (a) I did something harmful to the valve taking it off to clean it. Or (b) somehow have not re-installed it properly? Seemed pretty straight forward although getting the 3 hex head bolts off and on are pita. I tightened them down a bit but no difference. I'm going to take it back off and re-install again to see what happens.

Also interesting checking other vac lines. The line that goes from dizzy to top of plenum; take that off, nothing happpens, shouldn't that cause some sort of reaction? Finger over inlet, nothing.

Another thing, bear with me, I'm just learning this stuff. The actual stepper motor, was I supposed to take that off the alloy part and clean inside. Apparently acording to this pic of one, that looks like it should be cleaned. The one in pic is $29. The Lucas part is $189. WTF They list about 12 different part numbers that work.