1) Light claddering. I have 1991 RR with 169K and have heard light claddering at idle. Sounds like a metal flap perhaps controlled by intake manifold vacumm. Rev engine goes away. It has been doing this, oh maybe 50K+ miles so I don't worry.
If someone knows what it is I'm interested.
2) I had a intermittent dying at idle. Of course, it would only happen when my wife was driving ...
Finally died on me;
Air Stepper Motor is what sets idle (off the back side of manifold). It's controlled by ECU which sends pulses to regulate idle RPM.
It regulates the amount of air that by-passes throtle plate. It gets gummed up with oily muck since it pulls air after filter near the point where crank case blowby gets sucked into throtle body (before throtle plate).
This can be cleaned but it's delicate and not fully reliable (clean and see if problem goes away). See below for low cost repacement sources. I would go with AC Delco since it sounds like it has a better spring.
Clean out the mating suface also with carb cleaner and cotton swab. Good time to clean out screen on blowby connection to valve cover, looks like a small 2" can that screws into place with black hose going to other side air intake.
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http://www.rangerovers.net/rrpartsv.htm#stepper
Idle Air Bypass Valve (ETC6660):
The genuine Range Rover Idle Air Bypass valve (now fetching rather heady prices as the dollar has declined in value) has long been available for less than dealer prices from aftermarket sources; as of November 2003 it can be had for $169.95 plus shipping at Atlantic British and British Pacific, or $167.79 with free shipping at Speedycarparts.com. The Rover Connection now has an aftermarket one for $110. The lowest price I have found recently (November 2003) for the generic replacement (described below) is at AutoPartsGIANT.com for $36.58!! (search for fuel injection parts, 1989 Chevy Astro V6 -- subcategory idle speed control parts).
If you are interested in experimenting a bit, cheaper alternatives can be tried, at considerably lower cost than the genuine part or those sold by the traditional Rover aftermarket suppliers. Salvador, of Baja Rovers, Mexico, found that as we suspected the idle air bypass valve/stepper motor is indeed a GM part #25527077. He found the Napa part number is 2-1738. Phil Tetzlaff reports finding this part at his Boulder Colorado NAPA store, but later exchanged it for one manufactured by AC Delco, part number 217-437. It appeared to be of higher quality (in casting density and spring strength) than the Napa brand part, and indeed appeared to be exactly the same as the Land Rover part. The final kicker was that while the "genuine" Land Rover part is well over $150, the Napa part cost was $51.99, and the AC Delco only $38.51!" (However, prices have gone up considerably since then due to the fall in the dollar). Greg Olma suggests “Go to a junkyard and take your pick from GM 4 and 6cyl. I use PB'laster to clean em.” Richard Atkinson reports that this is perhaps the most popular GM idle air motor, and is eqiivalent to AC Delco part number 73312A, He says it also crosses to AC 17085051, 17086051 and 1717111288, amongst others, which were fitted to almost all 3.1L V6 from '90 - 95, '85 - '86 2.8L V6, as fitted to Cavalier and Celebrity, '85 -'92 5.0L and 5.7L V8 Camaro, etc. etc.
I have recently done more research into this mysterious part. Searching the NAPA parts directory, I did not find this genuine AC-Delco part, but they had an equivalent off-brand "Mileage Plus Fuel Idle Air Control Valve" part number MPF31738 for about $40 at Napaonline.com. (Glenn Coffman went to NAPA recently (June 2004) and they gave him a P/N 2-1738 for his 91 RR for $57). I found they had an alternative matching Echlin part number CRB21738 for $52.99 (a better known brand). I also discovered that the GM Part number 25527077 is the AC-Delco part number 217-437. Various internet GM parts sources sell it for around $50.
The lowest price I have found recently (November 2003) was at AutoPartsGIANT.com for $36.58!! (search for fuel injection parts, 1989 Chevy Astro V6 -- subcategory idle speed control parts).
Update July 2004: Cory Novak found that partsamerica.com & sister store Advance Auto have the Idle Air Bypass Valve for $27.99 in stock most of the time it is GP Sorensen 779-10003 & item number 5012678.
