MG-Rover.org Forums banner

HOW TO... clean the idle solenoid and solve hunting and erratic idle and revving...

35K views 52 replies 25 participants last post by  Kew 
#1 · (Edited)
Well I just wanted to give a little something back to everyone that’s helped me so far in my ZT journey of pain and pleasure so I thought that I’d knock up this little how to…

I’d been suffering from a couple of different problems. The first was that the car used to rev to about 2500 rpm when it was started from cold, just for a couple of seconds, then it would drop down to normal. Then over time it started holding its revs a for a second or two when you let off the throttle, so sometimes when changing gear it sounded more like an automatic as you let out the clutch and the revs were still quite high. Finally things got worse still when it started ‘hunting’ and the revs were fluctuating on tickover. It would drop its revs to 400 rpm and then rev back up to 1000 and then back to 400 and so on and so on.

My research and some advice from some top members on this forum pointed towards a faulty idle solenoid. The guys at xPart referred to it as the fast idle solenoid. I found a thread on the XPower forums on how to clean the idle solenoid but thought that I’d see if I couldn’t do a better job and throw a few pictures in to the mix.

Cleaning this has rectified all of the problems that I was having with my 190.

Initially I took it all apart and cleaned it as per the instructions that I found on XPower but the gasket on my car was badly perished so I then ordered a gasket kit from xPart for about a fiver and have taken it apart again to fit this. For the small expense, I’d recommend getting the kit and fitting the new parts when you do the clean. I had to make a temporary gasket out of a cigarette packet to put mine back together after the initial clean as the gasket was leaking air :) It worked like a charm but as you can see I’ve gone back and done the job properly.

A word of warning… Do this when the engine is cold as if you move the plunger on the solenoid, when you re-plug it in again it will reset itself to its cold starting position and you may find that the car won’t start or won’t tickover until it’s cooled down. I’ve done it with the engine cold and had no problems. Started first time and ran like a dream ever since! Others have said that their car wouldn’t start afterwards (because the engine was hot when they did this) but after 30 mins or so their cars started and ran as they should!

Right…

The idle solenoid is attached to a housing on top of the throttle body. It’s held on with two allen bolts and there’s an electrical connector (arrowed) and an engine gas return pipe (arrowed) going into it, as well as the pipe off the air box (arrowed). It’s nice and easy to get to on the 190 in between the engine cover, air box and battery box. The first thing you want to do is make some room by taking off the air box cover. There are two Philips screws on the top of the air box and also a hose clip (arrowed) on the large pipe that goes from the airbox to the throttle body. The cover then wiggles off and the pipes to the throttle body will come with it. The smaller pipe that goes to the idle solenoid housing isn’t held on with anything and just pulls off.





You’ll then have some space to see and you’ll notice the throttle body and air box pipe are full of oil (I’ll cover this in another how to as soon as I get some more parts that I’m waiting for), it’s worth giving them a wipe clean to prevent it getting sucked back into the engine (don’t worry, the engine will burn it as it’s been designed like this, but it’d be better if it wasn’t there).






Once you’ve got that off you need to unplug the electrical connector and the gas pipe (it uses one of those connections where you push the outer ring on the housing down and the pipe pulls up). Undo the two allen bolts and lift the housing off. As you can see below, my gasket is looking worse for wear with a torn corner.




You’ll now have the housing off as below and will need to remove the solenoid from the housing using a torque bit. Be careful not to move the plunger if you can help it and be careful not to lose the o ring that sits between the solenoid and the housing if you didn’t buy the kit with a new one!





I’ve arrowed the parts that need cleaned. They look ok now on mine as I’ve already cleaned them all but they were badly coked up the first time I took it apart. Some meth’s will probably do the job, but I used some pipe cleaner that I had handy. You should also clean the throttle body where the gasket sits so that you get a good seal when you put it all back together again.



The little yellow bit that I’ve fondly named the doozle wotsit sits inside the throttle body, under the gasket and it should be white like the new one. The gasket kit came with new bolts, the gasket, a new o ring for the solenoid and also a new doozle wotsit. You can see where that fits under the gasket in the pics below.








After cleaning and drying off the relevant parts. Refit the solenoid to the housing with the new o ring and new torque bolts. Fit the doozle, the new gasket, re seat the housing and tighten the allen bolts to the desired degree of tightness. Plug in the electrical connector, engine gas pipe and re-fit the air box.

There you go…

Turn the key and listen to her purr!! :Lol:


If i've missed anything then i apologise but i'm pretty sure that it's all there!


The above is a quick account of what I did and I had no problems and didn’t break anything. Just be warned that you do this at your own risk. This is simply an account of what I did so I can’t be held responsible for any problems that other may experience or cause as a result of the above.

:)

Enjoy!!
 
See less See more
9
#3 ·
Excellent, clear thread.
I'm trying to do some similar threads for changing clutch slave/master cylinder, and you can't beat good pictures.

Just for other peoples info - there is a very similar (but easier to get to) valve on the 'k-series' engines (I think a few are used on 75's) You can see a picture of it on a k here, halfway down - its actually in our Caterham, but same engine...
http://www.mycaterham.com/66828/66590.html

I'll see if I have more pics and maybe add them?

Thanks for the pics of the MG V6 version...
 
#5 ·
Excellent post 6raeme. I suffer from that 'holding of revs after I release the throttle problem', so I am really looking forward to solving that. I assume that part number written on the little plastic bag is what you order? I wonder will you get an improved mpg figure after your cleanup? Nothing major I suppose, but every little helps.
 
#7 ·
I just hope that i can help people like they've helped me flyer. I'll have to get my mate to sort out some How To's for the old burners so that we can hopefully give something back to you my old chum!

I've just fitted an oil catch tank that comes off one of the engine breather pipes to stop oil backing up in the throttle body. It was a simple job but if no-one's put any instructions or pictures up yet then i'll sort some out over the next couple of days

:)
 
#14 ·
Hi all great thread. Just a quicky. Is it just the housing that needs cleaning? Or dose also have to clean the motor also? And what is a torque bit? I'm new to all this. I hve however clearng to change my spark plugs, know how to do oil filter and change pollen filter and air and drain the catch area where the ecu site. So I'm learning thanks to you kind people here. .
 
#15 ·
The mushroom head and the tin tube behind it needs a good clean too. To access the back of the "mushroom" gently press the tube against the motor. It is hold there by a spring which will let you do so.
Under no circumstances do NOT try to rotate, push or pull the shaft with the mushroom head. The outer half of the shaft is guided longitudinally (if you move the tube you'll notice the channels) and the rotation is prevented by a small plastic profile in the stator. It is very easy to break it - no rotation allowed!
The inner half is screwed in the rotor - no push, no pull.

Great pics and good job but I need to point out once more: this is NOTa solenoid, it is a stepping motor with a guided shaft. Do no treat it like a solenoid if you don't want to buy a new one !
 
#18 ·
The mushroom head and the tin tube behind it needs a good clean too. To access the back of the "mushroom" gently press the tube against the motor. It is hold there by a spring which will let you do so.
Under no circumstances do NOT try to rotate, push or pull the shaft with the mushroom head. The outer half of the shaft is guided longitudinally (if you move the tube you'll notice the channels) and the rotation is prevented by a small plastic profile in the stator. It is very easy to break it - no rotation allowed!
The inner half is screwed in the rotor - no push, no pull
Thanks for extra info. I assume the "mushroom" is the white nipple (I know lowering the tone even more, Ha ha ha) that is on the top of the motor taken from the housing? Also can someone confirm to me that a Torque bit is just basically a Socket set ratchet with relevant socket or screw driver connection. I know i'm being a little dumb here but I have never heard of it and cannot find an answer on google (i know, I nearly fainted also).

If all of that is so. I will be off to the rover dealers tomorrow to get the gasket kit and be doing that on saturday. Very excited.

oh and before I go...... NIPPLE.......my how one makes ones self giggle!
 
#33 ·
The white plastic bit with 2 legs that comes in the kit - I extracted the old out of my housing quite easily with the aid of a screwdriver, but with the new one, I had to use some force to get it back in. What purpose does it serve? If its supposed to move, well, this one isn't going to as it's stuck fast now.
 
#35 ·
Job done. This has stopped the erratic idling, but when im over say 2000 revs, the throttle just stays there. If i give it a blip, the revs fall to 800 and stay there. I'm outta here to check out the changing of spark plugs.
Thanks to the OP and everyone else who has helped - cheers.
 
#40 ·
Hi Folks,

I took a stab at this wee job this afternoon. Simple enough job and it gives you an excuse to clean the inlet trunking and throttle butterfly as well. I didn't order the kit, so I just used some gasket/sealant stuff that I had lying around (same stuff I used to re-seal my VIS motors).

It took maybe 10 seconds to fire up after re-assembly, but all seems fine
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top