Bothal82 Posted November 18, 2014 Share Posted November 18, 2014 Hello I have a 1994 LWB Classic Range Rover 4.2 that I have just finished restoring and I am a little confused on where 1 particular vacuum pipe goes. On the rear of the plenum chamber I have 2 small male nipples where the IAC screws into.The part number for the plate where the nipples are is MKF100200. I have worked out from pictures that one vacuum pipes goes from 1 of the nipples to the fuel pressure regulator but I am stumped by the other nipple. The vehicle runs rough on idle if the spare nipple is left open and once blocked the engine idles fine. I take it that more air is been forced into the plenum chamber confusing the ECU. If you place your finger over the nipple it is sucking air rather than pushing air out. I have searched online for the plate on which the nipples are attached and they all seem to only have 1 nipple. What I am wanting is a diagram of where the vacuum pipes go as at present I have simply blanked it off with a piece of tube with a stop in the end. Any help would be appreciated. Regards David Quote Link to comment Share on other sites More sharing options...
rrr47 Posted November 19, 2014 Share Posted November 19, 2014 Can you take some pics? Does the pipe go to the cruise control? I had a similar issue with my 3.9, but in that case the LPG back fired and blew the pipe off, so it was easy to see what had come off. Quote Link to comment Share on other sites More sharing options...
Baeau Posted November 20, 2014 Share Posted November 20, 2014 Could this be of any help? Quote Link to comment Share on other sites More sharing options...
MikeAK Posted November 20, 2014 Share Posted November 20, 2014 Hi, Just checked on my 3.9 and that only has one nipple going to the fuel pressure regulator. But I remember my old 3.5 had two the second one going to the overrun vacuum switch which operated a relay to stop injection on overrun. This system was never fitted to 3.9 and 4.2 (as far as I know). the vacuum nipples are not on the plenum itself but on the separate casting the IAC screws into maybe that has been swapped for the wrong one at sometime in the past? In which case you could just blank off the extra nipple. On mine the cruise control has a separate electric vacuum pump and the vacuum reservoir for the heater controls is connected near the front offside of the plenum so I don't think it would be either of those. Mike Quote Link to comment Share on other sites More sharing options...
Bothal82 Posted November 21, 2014 Author Share Posted November 21, 2014 Hello everybody. Thank-you so much for your comments. I really do appreciate your help. After liasion with the very helpful Adrian, at Kingsley Cars Oxford, we have figured out that the second nipple or spiggot is used on only a limited number of classics. This is what he sent me: "There should only be the one nipple which goes to the fuel pressure regulator. BUT on some models a vacuum pipe, from a second spigot, operated a hot water valve via an electrically switched valve. The hot water valve is located on top of the right hand rocker cover in a Y connector in the water pipes. The electric valve is located on the bulkhead just behind it. http://lrcat.com/#39/4/49254 The tail of pipe number 8, I think, should go on the 2nd nipple." Indeed my classic does have this hot water valve so I have ran a pipe from the 2nd spiggot to this valve. I will try it at the weekend and report back. Those guys at Kingsley Cars are very knowledgeable and for someone to e-mail at 21:30 says alot for the commitment they have. Thanks again David. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.