Hey everyone. So I bought a 1996 Disco and drove it home with no problems. The next day, it wouldn't start. I bought a new brass negative connector for the battery and charged it up and it started right up. The idle was under 1000 when I did so.

The next day, I started it up and the idle was extremely high (3,000 to 3,500). So I turned it off. The day after the idle seemed to be back down to normal. It seems to alternate between ridiculously high and normal every so often.

What might be causing this? Faulty TPS? Resetting the ECU? Any opinions would be wonderful.

I really need to get it fixed because this will be my main source of transportation when I move out of state in a week or two.

Thank you very much!

***EDIT : The truck has 128,000 miles and had the head gasket fixed a few months ago. ALSO, When I start up the vehicle it revs high, and then drops down VERY low (500 rpms) and then settles there. However, when I rev the engine in park, it rises to about 2,000 rpms and sticks there. When I drop it in reverse or drive, the rpms shoot down to about 750 where it should be.

 

First off, welcome to the forum. Second, there are some factors you need to share with the class if we are to be of assistance. Mileage, condition and any recent work you or the PO have done. Pictures of the trouble areas help too.

Others may disagree with my stance on this but if you have a few bucks ($200 or so) and since this vehicle is new to you, I suggest you start ownership of this '96 at a base level of maintenance. This will help you rule out some of the most common issues. Disco Mike has a great thread in the sticky section (https://landroverforums.com/forum/sh...ad.php?t=29020). Best part is you'll at least improve your odds of having a better running rig.

Change out the spark plugs, Leads from coil packs, fuel filter, air filter, ALL VACUUM LINES, oil filter and oil...etc...basics. Mike may disagree with this but in my opinion clean the MAF with MAF cleaner and pull the IACV out to clean the mating face between the cone and plenum. Clean the throttle / butterfly valve seat in the plenum and check for any air leaks around the plenum seat (where it sits on the intake manifold).

Your idle is controlled by many sensors (Fuel temp, Fuel pressure, Coolant temp, Air flow, O2 sensors, measured idle speed, measured road speed, and the ECU...the list goes on...) at differing stages of warm up and vehicle movement so you may end up chasing your tail if you don't have good spark and fuel delivery to start off with. MOST importantly download the RAVE manual: this book will answer just about any question you will have. the link is below in my signature.

 

when was the last time you did a good maitenance on your truck? plugs, wires, induciton cleaning, cleaned the throttle body, what type of air filter are you running, when was the last time it was changed?

 

I would suggest you clean the t/body and the IAC, both the plunger and the hole in the manifold, cause carbon, or in the case of the t-bofy, will cause the idle to do really weird things.

 

***EDIT : The truck has 128,000 miles and had the head gasket fixed a few months ago. ALSO, When I start up the vehicle it revs high, and then drops down VERY low (500 rpms) and then settles there. However, when I rev the engine in park, it rises to about 2,000 rpms and sticks there. When I drop it in reverse or drive, the rpms shoot down to about 750 where it should be.

 

So, have you looked at what I suggested yet?

 

I agree with a bad/dirty idle air control valve (IACV).
http://www.roverparts.com/TechTips/boschvsgems.cfm
It is the thing closest to the throttle body opening, remove it and do NOT move the plunger but clean it and clean the port it goes into with carb cleaner.

 

Wow, this is a fantastic forum full of willing and friendly people. Thank you all very much for the helpful replies. I will try all the suggestions and post my results here!

By the way, how will I know if I need to get the TPS replaced or the ECU reset? (I read another member's post that the TPS was the culprit of his truck's strange idle, which is why I was asking).

Thanks again!

 

The only way that I can think of would be to replace the TPS and then if it continues have the ECU reprogrammed.
The TPS is cheaper than a trip to the dealer.
But try the other stuff first.

 

Hey guys. I cleaned the MAF and Throttle Body (with respective cleaners), and I noticed it idling much smoother. As for the throttle sticking when I revved it in park, my mechanic friend put a C-clip on the throttle cable (I believe) so it wouldn't go past a certain point. I'll have to ask him exactly what he did and report back but fortunately these things seemed to have fixed my idle problems!

Weird thing happened yesterday... the 4x4 selector was in N and my main selector was in D so I'm assuming it was rear wheel drive as I have been driving it around when all of a sudden, without me changing anything, there was no power being delivered to the wheels. I would press the accelerator and the engine would rev but it was acting as if it were in Neutral. I was on a busy road too so I was frantically trying to fiddle with things, so I put the main selector in N and the 4x4 selector in H and suddenly I could get power in 4x4 High.... does anyone have any idea about this?

Thank you guys!