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Idle Speed Adjustment

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I appreciate that this has been done to death! But I can find nothing to help me!

1989 90 with a Defender 200Tdi (used to have a 19J).

This has been "resting" for about 3 years and I'm now getting ready for an MoT. In my view (and I don't have a rev counter) the engine is idling too fast. 

The throttle cable is adjusted so it is loose. The throttle idle screw on the injector pump had a broken slot (so couldn't be adjusted from the rear), but I've got locknuts on the front part now, so it can be adjusted and that is backed right off with daylight between the lever and the adjusting screw.

In that position, at idle, I can adjust the throttle cable until it just starts to affect the idle speed, then back it off.  So I am sure that neither the throttle cable, nor the throttle idle screw are affecting the idle speed.

What do I look at next?

Any ideas?

Or could it just be internal stiction, the engine has been started, but the car not moved more than a few yards for several years, could a good run loosen anything up that is holding the idle speed high? Do I find that (hopefully) after passing the MoT and using it, one day, at a set of lights it will just stop because the idle speed is too low :-)   



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It sounds to me that you really need to work out if you actually have a problem with high idle or if you're just chasing a problem that doesn't exist.

However, it's not uncommon for the internals of an injection pump to stick due to lack of use, but the only time that's happened to me was on a 90 I bought years ago that had been offroaded and dunked in water, driven home and parked up for 2 years. There was rust inside the injection pump as I could see rust on the boost pin and on half of the diaphragm disc, and although it idle'd fine it made the engine sluggish to rev some of the time but then clear and run fine other times. As a complete opposite to this I currently own a 200Tdi Discovery that hadn't been started in over 10 years and is absolutely fine.


Edited by Tetsu0san
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  • 2 weeks later...

Couldn't work out the idle speed, my contactless tacho using a reflective strip broke and nowhere safe to put an old smiths contact type. I think there must be a degree of stiction, I adjusted it until it sounded about right, but when I revved it, it died! So had it ticking over slightly faster than I would have expected, but usable!

The main thins is it passed the MoT today! My son checked, the last one was 8 years ago! Before I start messing with the injector setting I'll just drive it a bit and see if things free up :-) 



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