First, I would like to commend this forum. I am a recent owner of my first land rover, a 98 Disco, and this forum has helped me immensely in troubleshooting. But I seem to have hit a bit of an impass with my current problem.
I purchased my automatic 98 Disco with 89k miles about a month ago. The previous owner is a friend and he had the oil changed before I picked it up and drove it about 400 miles home. Unfortunately, I didn't check the dipstick before I left and the oil was far overfilled for this long trip back. Subsequently, oil was forced into many placed it shouldn't have been. The Disco ran fine for a couple of weeks, though it does leak some oil onto the manifold which smells. Last week I stopped to fill it with gas and it would not start. I then let it cool for several hours and it started and ran fine until it heated up then it would die anytime the RPMS dropped below 2500 (ie come to a stoplight or slow to make a turn.) It then would not start until it cooled off. The problem repeats it self. But there was no check engine light.
1) I replaced the fuel filter
2) cleaned the Air Mass Controller
3) cleaned the throttle body and air intake with GUMOUT
4) Cleaned the idle control valve
The Disco ran well but I got a check engine light P1508. This warns of an open circuit to the idle control valve.
Sure enough, I mistakenly forgot to reconnect the idle control valve wiring. Except, when I connect the idle control valve the check engine light goes away but all the old problems come back. I thought I clearly had a bad idle control valve. So I purchase a new one made by LUCAS ($200 OUCH!) BUt even with the new ICV I have the exact same problems. The car runs fine with the ICV disconnected although it idles high when in park and ofcourse I get a check engine light for the open circuit.
I am stumped!!! Any ideas? Did I get a bad/wrong ICV or am I troubleshooting the wrong part?Other possible areas to trouble shoot?
Any help is appreciated!
Thanks,
Craig

 

First of all, don't try to clean the MAF unless as a last resort. They are $600 and unless it is throwing a code to indicate, don't touch it.

Check the vacuum hose going to the LH valve cover. I think the IAC feeds off that. I think there is an oil filter thingy (looks likea little plastic crankshaft) to keep oil from going into the throttle body from the valve covers. Make sure it isn't plugged with carbon and that the hos is free and clear (also not leaking).

I take it you have corrected the oil level problem. I would look at the throttle body again to make sure everything is clean.

 

What is it with people, their truck gets a hick-up and the first thing they do is go and ruin their MAF's by cleaning them. To this day, I have never seen a sticker on the MAF saying clean me first!

 

It doesn't help that there is an aerosolcleaner made specifically for MAF sensors.I saw a can at the parts store and I bought it thinking it would be good preventive maintenance to clean it. Hell, they make a cleaner for MAF's,I figured they must get dirty. Luckily I found some posts on here about cleaning themand never used the stuff.

 

Wow. I had no idea cleaning the MAF was so trecherous. CRC a brand I have trusted for years with electronics parts makes a specific formula for cleaning MAF's. It advertises to clean the MAF every 60k miles.

Thanks for the reply, I did replace the vacuum hose from the valve cover to the throttle body.The old hosewas deteriorated from the oil that clearly sucked through there. However, I didn't notice a " little plastic crank shaft"? Just a nipple on the valve cover and a nipple on the throttle body. I put hose clamps on my new hose but the old hose was just pressure fit and quite loose. I will check again this afternoon.

 

That is intended for a Hitachi MAF. They should state that on the darn can, but they wouldn't sell as much.

I am working on a Bosch-Hitachi MAF conversion. Did it on my Audi like many others have. Audi got wise after the first year they made my car and thenswitched over to Hitachi MAF's on all of the 2.7 liter twin turbo motors they have.

The main difference between the Bosch & Hitachi is oil, dirt, etc. do not affect the Hitachi. It's a completely different sensor in the housing.

Biggest issue to do this with the Disco is re-mapping the ECU.

Once I have it completed I will post a full write up, pics, prices etc.

 

Could it be leaky injectors? With out the ICV the engine is running on all the fuel that is being dumped into the cylinders and with it the ECU is turning down the idle RPM to control the engine speed?
Are you sure the crankcase was just overfilled with oil and not with a oil/fuel mix? And the reason it will not start when hot is it is flooded and the fuel needs to leak past the rings?
I had this happen on a Cummins ICX engine, overfilled the crankcase with so much fuel that it actually started to leak past the turbo bearings and the exhaust smoked so bad I got pulled over on my way to the shop.
Just a thought.

 

Might just be on the passenger side. Mine didn't have one on the drivers, but I put one in to be safe. If you pull off the pass. side hose, look into the metal tube coming off the cover. There will be a little black thing in there...

 

Thanks for the tip. I did find this plastic piece inside the nipple of the LH valve cover. However, I was unsure as to how to clean it. does it pryout? Should I spray some gumout down into it? The hose did have some oil coating the inside but there were no leaks. Apparently it sucks the air from the throttle assembly. This must lift up the black plastic "cam" you referenced. I am just wondering how to clean it?

 

That cam looking thing is the oil sperator, I used plyers and grabbed from the top and pulled it out and then sprayed it with carb cleaner and replaced that vacum line.
Do not spray down into the valve cover, you do not want carb cleaner in your motor oil.