At first I was experiencing quite an erratic idle. Most days it would sit around 850-900rpm, but then on occasion it would jump up to about 1200rpm for the duration of a drive. If I turned the car off and on again it wouldn't actually fix anything, unless I had properly turned it off and let it cool down before starting it back up. But even then, when I started it back up it was a lottery to see where it would idle this time.

Now after removing the air conditioning my Mini has begun to consistently idle around 1500rpm whether it's hot or cold. I've done some reading, and found the little trick to reset the stepper motor, but this hasn't fixed any issues. My next guess is vacuum, but there sure is a lot of random vacuum tubes going every which direction. It doesn't look like a fun job to start tracing all of them, so I was wondering if anyone could point me in the direction of the "common problem areas".

Also, when I removed the A/C I broke a silly little tube the ran from the airbox opening down to the throttle body area. The little tube was sooo small, I couldn't imagine it actually did anything. Of course it is first on my list of things to replace, but could anyone tell me what this tube is for? Furthermore there is a round protrusion on the airbox inlet, but I can't open it up. I am now really curious what is in there and what purpose it serves. Can anyone tell me what it does?

Lastly, I also read that if a coolant sensor goes bad, the ecu will continually richen the mixture to try and cool the motor down. Is this true? I don't think this is my issue because my temp gauge reads normal - but the post I was reading says the temp senor is under the intake manifold. Can someone verify this? I know there is a sender in the bottom of my radiator - is it possible that the radiator sender is simply for the gauge, whilst the sensor under the intake is for the ecu?

Thanks guys!

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1998 Rover Mk VII
2001 Honda CBR 929RR (street)
2014 BMW S1000RR (track)

This little tube is just a vacuum supply for the hot/cold flap in the airbox inlet - not a biggy.

BUT - there should also be a second small tube like this from the back of the throttle body (connected next to the one you asked about) that will go to a small box (not much bigger than a matchbox located to the left of the inlet chamber when looking from the front), then another small tube goes from that box to the bottom of the ECU. This lets the ECU measure the inlet vacuum and is used to help set the idle (among other things). Very common problem is the rubber connectors on these hoses perish and crack - causing leaks.

Getting replacements of these rubber fittings is like locating NOS Hens teeth. I eventually made up new ones by getting two sizes of rubber vacuum hose - can't remember the sizes off the top of my head but one fitted the manifold/black box/ECU fittings, and the other was a tight fit over the plastic tube AND could could be persuaded to fit inside the first hose with a bit of force. I also used a smear of silicon sealant to "lubricate" the insertion of one tube into the other which would then set and strengthen the join. If you go down this path make sure the one that you make for the back of the throttle body has the wider tube long enough to get around the hard bend needed there before you join the hoses.

On the side, there should also be a wire that goes to the bottom of the airbox too. This is for the inlet temperature sensor in the airbox. Try not to start the engine with this not connected otherwise you may end up with a sensor fault that will have to be cleared using an external engine management box. This fault can cause the engine to run rich.

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..

First of all where are you located? And the hose in question is a vacuum hose, block it off and see if it makes a difference.
Cheers Pete
P.S These are the hoses in question.
1) http://minispares.com/product/Classic/F ... o%20search
2) http://minispares.com/product/Classic/F ... o%20search
3) http://minispares.com/product/Classic/F ... o%20search

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A recent study found the average Aussie walks about 900 miles a year
Another study found Aussies drink, on average, 22 gallons of alcohol a year
That means, on average, Australians get about 41 miles per gallon

Kind of makes you proud to be an AUSSIE

Thanks guys!

I've got a big order in at MiniSpares already, so I've just sent off an email to see if it's shipped yet. Hopefully they can throw in those 3 hoses - and you're right - they couldn't have possibly designed them to be stranger sizes and connectors. What ever happened to some 1/8 pvc tubing??

I didn't realise one of these vacuum tubes went directly into the ECU. I'm guessing this is my issue because when I removed the A/C condenser, an ECU mounting point was removed too. I've got a "temporary solution" which isn't extremely sturdy, and I"m willing to bet a bump has knocked that thing right out from the bottom of the ECU. I'll be checking first thing when I get home tonight.

(And I've updated my location - Bentleigh, VIC)

Legends. Love this forum.

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1998 Rover Mk VII
2001 Honda CBR 929RR (street)
2014 BMW S1000RR (track)

Has your's got the big hole in rh inner guard now? If you're in the process of repairing it, refit ecu there. There should be plenty harness wire length. What about air intake for fresh air, have you the silly little one about 50mm hose? (like 20 in picture) You can remove the air intake on rh inner guard (9) at back and remove the reducer bit (not shown), then fit the larger hose (3) and scoop (2) to get heap more into the car. Hose 3 is no longer available but you can get it non genuine.

https://www.minispares.com/catalogues/c ... x?2~19~185

this might interest you, too

http://www.ebay.com.au/itm/301041626954 ... 1555.l2649

With regards to the temp sensors: the one in the bottom of the radiator is the thermoswitch. It's connected to the fan behind the radiator and nothing else.
All it does it switch the fan on / off according to coolant temperature.

The sensor in the inlet manifold (its screwed in from underneath) is the one that tells the ECU what to do. The ECU controls what you see on the gauge.
I had a fast idle issue with my car for a while, replacing this sensor and the air inlet one together fixed it.

The round thing on top of the air inlet tube is a vacuum operated flap. When the car is cold, the flap brings air into the airbox over the exhaust manifold to warm it up.
Once things have warmed up a bit, the flap closes and it breathes air from in front of the engine. The thing that controls the flap is just a funny 'wax and spring thing' if that makes sense. There's no connection to the coolant or electrical devices, just the generic temperature of the engine compartment and intake air.

I disconnected the thing - it doesn't really have much relevance in this country.

Bit game living in Melbourne and making comments like that

You guys are awesome. Unfortunately, no dice with the vacuum leak.

All the hoses were properly connected (sans warm air flap), and I checked the fuel trap for flow. It was allowing one way air flow from the throttle body towards the ECU. OF course, if I unplugged either hose from the fuel trap, the car barely kept ticking along at about 500rpm.

I gave it a go sniffing the exhaust fumes, and it didn't seem to be running overly rich - but I must admit I didn't pay close attention when it was running fine. I think if it was saturated rich than I would notice it easily.

So onto the inlet sensor. Thanks for the info regarding the sensors and the hot air flap Harley. You said in your post, "replacing this sensor and the air inlet one together fixed it.". Does that mean there's two, or am I reading this wrong? What do I need to remove in order to get at the sensor? Removal of throttle body? Inlet manifold? Do I need to replace any gaskets while I'm in there? Any words of wisdom for the process?

Lastly, I'm meant to pick up my buddy from the airport on Wednesday. How much potential damage am I doing driving under these conditions? Could I be causing harm to the cat, O2 sensor, spark plugs, valves?

As usual, thanks fellas!

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1998 Rover Mk VII
2001 Honda CBR 929RR (street)
2014 BMW S1000RR (track)

You first mentioned this is mainly a problem since removing the AC: what did you do with the wiring? Don't suppose the car thinks its connected and has activated the idle up feature?

For sensors, there's a water temp sensor and an inlet air temperature sensor (well, and also crank angle, mass air flow, throttle position and oxygen).
Replacing the air inlet sensor is easy, its just screwed into the bottom of the air box.
Replacing the water temp sensor is straight forward, but fiddly. The throttle body assembly needs to be removed from the head to get to it.
I've done it in the car without draining the coolant or disconnecting the fuel hoses - though it is a bit messy and you risk getting coolant into the cylinders if not careful.

Generally speaking the only problem with running injected minis with dodgy sensors is if its getting too rich, the oxy sensor can fail as a result and things get worse from there. Ignore the cat - its probably not working anymore, valves will be fine, plugs are cheap and easy to change if you need to.

also worth a check is the TPS, they wear and the ECU don't know if the throttle is closed giving a higher idle speed than normal.
as MAP is the main source for the ECU its hard to tell if the TPS is broken during regular driving. but you can find out with a DMM measuring the TPS resistance while moving the throttle

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Rover 214 atm ....

Brilliant info.

So on the way to work this morning she was idling fast for the first 10 minutes. After warming up, I hit a stop light and killed the engine simply because I hate listening to it hum along at 1500rpm. When I started it back up, everything was perfect. Idle at ~850rpm, and she ran great for the next 45 minutes into work, with plenty of sitting in traffic and idling. Ugh. Intermittent problems are so much harder to troubleshoot.

So now I'm really hoping the problem has solved itself, because I've got huge amounts of driving to do over the next two weeks, and don't know how hard the parts are going to be to source. I've also never taken on a job like this so far - I'm keen to learn more and become familiar with new bits, but I know it will be a slow and methodical process as I tear it down. So onto more questions for all the guru in the room...

If my Water Temp Sensor has gone bad, wouldn't the gauge reading be off? As far as I can tell it reads normal (perhaps a smidge colder than usual)

If I do decide to purchase new sensors, can anyone help me confirm that I am looking at the right bits? I figure if I'm in there already, I might as well replace the following:
http://minispares.com/catalogues/classi ... x?2~20~189

#9 - Sensor for Inlet Air Temp
#10 - Water Temp Transmitter
#4 - Oxygen Sensor Unit

And what is this sensor? It seems to me this was juts the "go-between" for the hot air flap vacuum deal. There weren't any electricals connected to it. Wtf?
http://minispares.com/catalogues/classi ... x?2~18~175

#29 - Temp Sensor


I'll report back as I learn more! Thanks everyone!

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1998 Rover Mk VII
2001 Honda CBR 929RR (street)
2014 BMW S1000RR (track)

#4, 9 and 10 you have right.
Ignore #29. the car will work without it, that's why the part is no longer available. Its just a wax thermostat.

If the water temp sensor goes bad the gauge doesn't always reflect that. I don't know why, that's just what can happen.
The sensor isn't connected to the gauge. They're both connected to the ECU but not each other.

a hint if the water temp sensor is broken is that the temp gauges reaches "normal" much faster. the ECU don't know the temp and just triggers the gauge to normal. noone knows why, as triggering it to "hot" or keeping it to "cold" would be much more helpfull indicating a fault.

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Rover 214 atm ....

So, things have seemed to improve themselves. The car is now idling very consistently at about 960rpm, which is a touch high but much less worrisome than 1500rpm. I think the car is certainly running rich, though it feels and drives normal my stats reflect approx 8.3 l/100km, whereas my average sits closer to about 7.3.

As for the temp gauge, it behaves very normal. It takes a normal amount of time to reach mid-temp, and I can even see small fluctuations when I am driving down the motorway vs. sitting in traffic.

So what do the experts think? Should I be worried about an extra litre per 100k? Is this going to quickly foul my O2 sensor, or will it take ages? Every time I drive the car I feel like I am killing it, and on Friday I am meant to drive out to Phillip Island. Am I being a little too crazy?

And, at the end of the day I think I will replace all three sensors, but I just don't know when I will find time. I really would appreciate your opinion of whether I should park the car until I sort it, or if it's ok to turn over another 500km before it's fixed.

Thanks guys.

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1998 Rover Mk VII
2001 Honda CBR 929RR (street)
2014 BMW S1000RR (track)

If you're going to replace them in the next 500km then the car will be fine to drive around in.
If it worries you too much ditch the injection and fit a carby!