Fault Code 48/fast engine idle speed - Defender Source
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  #1  
Old January 11th, 2006, 04:02 PM
arbik
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Fault Code 48/fast engine idle speed

Hi guys,

so this is what happens, when you muck with a rover that's running decent.
I took out the idle stepper motor, cleaned it, then cleaned the vacuum hoses from the engine breather. They were clogged, so I opened them.
Now, as a result, my engine is running fast, and check engine light is on, and shows fault 48.
This is idle speed/stepper motor maulfunction. I'm hoping I didnt screw up the stepper motor during cleanup. (used carb cleaner to get the gunk out).
I'm sure, at some point...the mechanic for the PO had adjusted the idle speed up, to adjust for the vacuum lines being clogged, etc. So now, its runing too fast, with the lines working as they should.
So I need to adjust the idle. Where is this located?
I'd rather not guess, and screw something else up.

Thanks,

-arbi
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  #2  
Old January 11th, 2006, 09:40 PM
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Make sure there are no vaccume leaks, then try resetting the computer. If you fixed a problem that the ECU was trying to adjust for the ECU will still be trying to adjust for it and may be running high in RPMs because of that. Resetting the ECU will force it to readjust and run right. But make sure there are no leaks first.
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Old January 11th, 2006, 09:53 PM
arbik
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Thanks for the reply mike.
I dont know what the hell it was that I cleaned on the truck. (I know, I'm ashamed to admit it).
Its on the passenger side, on top of the engine. Its like this large bolt looking thing, with a connector attaching to its end. It screws into the intake manifold plenum housing (95, 3.9).
I might have mucked it up while trying to clean it. I used carb cleaner..and jiggled the little bayonet looking thing with a spring around it a bit.

What is that thing?
my guess would be its the cold idle solonoid..but other than that..I have no idea.

as far as I know..there are no vacuum leaks..
I took the hose out (the one that had a clogged connection in it..and closed it off..and the idle seems to fall when I do that.
I'll reset to night..and see what happens..
any other ideas?

-arbi
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Old January 11th, 2006, 09:54 PM
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Yep, I agree with Mike on that. If that doesn't help, then the idle screw should be on the top of the throttle body toward the back, it may be covered with a little thin metal cap.

If you see a little metal disk, with a hole drilled in it, then you found your idle screw and the hole means somebody else already adjusted it at some point.

-Hans
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Old January 12th, 2006, 10:17 AM
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It sounds like someone adjusted the base idle speed with the tee orifice plugged, and now that you've cleaned it, it needs to be set correctly. The base idle adjustment is as Hans says...under the thin metal cap on the plenum. It is a 3/16 allen if memory serves correctly. I would pull it out and clean it and it's bore with carb cleaner. Reinstall it by bottoming it out and then backing it off 2 turns. That will give you a base adjustment where the truck should run and idle and you can fine tune it with the service proceedure from there. The part with the spring and plunger is the stepper motor. Cleaning it with carb cleaner is fine. The main thing to remember is not to lose or damage the gasket that should be on it and to make sure the threads are sealed. Also check the housing that it threads into. It is held to the back of the plenum with allen screws and I've found a few of those worked loose causing an air leak and high idle.
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Old January 12th, 2006, 08:11 PM
arbik
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Good advice.
I'll check those.
Is there a way to disassemble the stepper motor and check the insides?
I noticed there is a rod that goes from one side to the other side of the assy.
I think I might have busted mine out.
also, I dont remember seeing a gasket on there....
are these parts servicable, or should I just get a new one?
also, as far as setting the idle. is there a place online that has the procedure outlines?

thanks again guys..
this board makes owning a land rover almost as painless as a jeep

-arbi
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  #7  
Old January 12th, 2006, 08:25 PM
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Setting the idle is pretty easy actually once you get to the screw. Just get the truck up to operating temp, then dial it down until it hits 750 or so. The idle really won't go any lower, since the stepper motor will open up to raise it back to the proper level. So make sure not to turn the idle screw down too much.

-Hans
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Old May 29th, 2006, 02:47 PM
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Does anyone know what the Fault code 20 is?
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Old June 2nd, 2006, 01:11 AM
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Fault codes
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Old June 2nd, 2006, 07:02 AM
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The stepper motor fault is usually set when the ecu tries to step the idle motor to the fully closed position and the idle is still too high. Note that you'll get a fault when the idle motor is close to closed, not fully closed. The ecu needs some travel room if it needs to drop idle more, or to put it another way, the idle speed has to be controlled by the ecu/stepper, not the base idle screw.

The screw is probably out too far. In addition, the timing may be advanced too far. Both will set that code.
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