So, I'm having problems with rough idle and stalling in my Disco 1. I took it to an import specialist, who cleaned the throttle plates, and MAF sensor unit etc. He said I MIGHT need a new MAF...which is a pretty wishy-washy thing to say. He said that my fuel-pump is good, and fuel pressure is good.

It's still running like crap, and even after driving for 30 mins or so, the idle will still drop to where the engine sounds/feels like it's struggling. It runs fine when I'm not at idle, and whatever the mechanic did, definitely helped my throttle response and acceleration.

I'm going down the list of stuff to try, to fix the issue. I've got a new set of STI 8mm plug wires to put on tonight, and someone put newish plugs in it, so I'm going to check the gap on those too.

I pulled off the IAC motor, and it was pretty nasty....gummed-up. I cleaned it with some carb cleaner, but everyone says to not turn the plunger while it's removed......but before I read that, I tried to turn/move the plunger but couldn't. I haven't tried to see if it moves while plugged in with the engine running, but if people are saying "don't move it!", and yet I was not able to move it with reasonable force, is that a solid indicator that maybe my AIC motor is stuck, and I need a new one? Could this be the main cause of my rough/low idle and stalling?

 

Yep, it is called the idle air control valve for a reason - at idle that stepper moves in/out to control the vacuum leak. You can replace it, ECU will have to re-learn it. With it out, and key turned on, you would see pintle move in/out as part of startup. Yu also want to clean the PCV lines that go from balve cover to the throttle body, and the pleunum on the passenger sie. On teh passenger side valve cover these is a oil separator that will likely be gunked up and need carb spray.

You really don't want to buy a new MAF......

 

Thanks Savannah Buzz! I put my new plug wires on last night.....and found that my PCV oil separator was plugged. My Disco SEEMS to be running a bit better today.

 

can someone explain and show me with pictures if possible HOW to remove and clean the IAC on a Discovery 1 ??

I already cleaned the MAF but the IAC is next and dont know where/what and how it looks like...

Thanks

 

What year is your DI? The '94 and '95 use a different fuel injection system than the '96-'99 so the IACV is different and in a different location.

The '94 and '95 DI's have their IACV on the back, passenger side of the plenum (that big thing shaped like a T that has 3.9 on it. It screws out.

On the '96-'99 DI the IACV is facing you, immediately past there the intake hose connects to the plenum. Adjacent to the IACV is the TPS. The IACV is held in place with two small bolts.

 

Just a Note to let everyone know that you guys on this Forum are AWESOME!
This is my first D1 and I have to say it has been the easiest car to figure out and work on...especially with your knowledge and help.

I wanna personally thank :
Savannah Buzz
and Paul Grant
for promptly answering and being of Great Help...keep up the good work guys I'll talk to you soon..Im sure.

Cheers