Idle control valve (idle stepper motor) is certainly something anyone running Rovers (aka Rangies) should know about. It sets idle speed and is controlled electronically. The engine electronics (ECU) sends pulses to the valve which allows air to "bypass" the trottle plate.
Most common problems are erratic idle (too low/high/varies), sometimes ok/not ok, dies at stop light intermittantly, idle at start problems. And the RR Clasic is my worse offender.
My 1991 RRC recently would occassionally die at starting when put in gear. Problem: Idle bypass valve dirty and slow to react. Previous problem - occassional dying at idle usually hot day, wife driving.
My 1997 Chevy Tahoe would not instantly fire up at start without tapping throtle. Problem: Idle bypass valve dirty and slow to react to computuer.
My 1985 Porsche slow idle at warm up. Problem - Idle bypass valve.
Issue; Valve gets gummed up and the spring just can't overcome the gunk.
Solution: Clean with carberator cleaner (or such).
Sometimes they need replacement:
Here is good site to study for parts and what is shown on this topic.
Classic - 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 2-1736 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.
Rover 4.0/4.6 - Idle Air Control Motor:
This item (ERR4352) is not a constant troublemaker on the 4.0/4.6 as it is on the Classic, but on the downside it has certainly been known to fail and is even more expensive than the Classic equivalent. Lee Schierbaum did have such a problem with his 1996 4.0 and instead of the $200-plus genuine item he located a NAPA replacement part (Echlin #2-1856) for $52. The part also fits a Jeep. Another part number I have seen for this is AC-151. If you would rather use a regular Rover parts supplier so you know for sure the unit will fit, the best price I have seen for this part (October 2004) is $139 at British Pacific (part number ERR4352).
glenncof: I have used NAPA replacement for my Classic as this engine is a GM Buick design.
Last edited by glenncof : 02-11-2005 at 08:22 PM.