32 replies to this topic

[jamesy]

affraid i dont know how it works enough to help you much further, and my own is currently in 101 bits so cant check that. your definitly on the right place on the inlet manifold?

 

flyingscot is the man for the job.

 

dont give up on the injection yet!

[FlyingScot]

When did it start doing this? Is it a recent issue?

Vacuum pipes come complete with elbows and I normally recommend whole replacement along with the fuel trap as they are service items.
The ECU has the MAP sensor inside and without the vacuum system being connected the fuelling won't be correct for the engine load. The system relies on all the sensors working and is generally reliable if maintained. When current the cars were connected up to the dealers Testbook system when serviced and any faults could be read and corrected. Sensors tested and rectification made.
Maybe there is someone local to you that you could borrow a code reader from (see in the pinned thread) as this would give you a better idea of what is going on.
Expecting the system to work properly when half the bits aren't connected is a bit of a stretch, it will be in "limp home mode" which is why it won't be able to rev or pull properly. The MEMS ECU itself is quite robust but like all minis poor wiring and bad earths can also take their toll by confusing it.
One of the main "problems" is that the system will try and do everything it can to get and keep the car running which means that series of problems develop overtime and only when they become an annoyance does investigation begin.
Often when I read the ECU for faults they have 8 or so logged on cars like this with 2 or 3 live issues.
I have both injection cars and carbed ones, the joy of the injection is that I can jump in any weather and she will start and be able to drive away. I'm old enough to have had minis when carb was the only option and fannying about at the side of the road with a timing light, feeler gauges and trying to set the mixture by ear or colortune wasn't my idea of fun

FS

[minifreek1]

Thanks for the help so far folks...

 

@ FS - I bought the Mini in November, it did have a bit of a running issue when I took it for a test drive but I put that down to it being cold...

 

I happened to find the 'spare' vacuum pipe when I was replaceing the top engine steady bushes (against the bulkhead), I did ask on here where it was supposed to be located... I found that it should be located at the ECU and to the vacuum pipe connection on the rear of the inlet manifold (on the left side as you look at the car from the front)....

 

Once connected - it runs fine, but you kinda have to keep pumping the throttle to get the engine to rev. If you basically just floor it, the engine tries to die, as though its flooding...

 

Obviously i want it to run properly, because I wont be letting this Mini go at all..... It must be a problem this car has had for a while with the vac pipe being disconnected, I can only presume by a previous owner... the lad I bought it from didnt seem to know anything about the car, nevermind what had been done to it to maintain it and to keep it on the road....

 

I did however get given a box full of bits, which includes an inlet manifold and complete TB and a few other gubbins for it....

 

I shall try the TB reset, with everything connected and take it from there....

[minisprint]

Pull pipe off fuel trap the one that goes to ecu, put peice of vac pipe on fuel trap and block off . Now run car and suck on vac pipe to ECU does engine run better?

[minisprint]

Need to get mini on a diagnostic scanner to read live data with engine running, should show map sensor pressure throttle pos etc

[miniBrain]

Hi Minifreek1,

 

I've recently converted mine from carb to fuel injection and I will *never* go back to carbs - injection is so much nicer to drive, albeit more complicated and probably less reliable. My advice would be to fix the injection - from what you've described your fault may not be too serious.

 

Based on general knowledge of ECUs, the fuel is metered in accordance with the manifold pressure (or vacuum) - low pressure = low load = low fuel flow; high pressure = high load = high fuel flow. So disconnecting the vacuum pipe from the ECU would cause the sensor to read atmospheric pressure (falsely indicating full load) resulting in higher fuel flow. I'd hazard a guess and say your fault could be a weak fuel pump and/or blocked filter. If fuel pressure is low, then disconnecting the vacuum pipe could compensate up to a point - but should be pretty horrible to drive.

 

If you wanted to quickly check the fuel pump you could disconnect the fuel pipe to the throttle body inlet and connect a hose from the fuel pipe into a 4 litre container. Switch the ignition on and the container should fill at 1-2 litres a minute. If you try this, the temporary hose needs to be securely held in place as it will "snake" around if your fuel pump is working properly. A better test would be to connect a pressure gauge if you can get access to one (although they are pretty cheap to buy).

[minifreek1]

I happen to have a Facet FPR with a pressure guage attached to it, Im sure it won't take much to adapt it to the mini's system...

 

 

 

I will be taking a look a bit deeper when the nicer weather starts to be a bit more common than it is at the moment....

 

I shall also try the advice suggested by Minisprint and block off the pipe and give the other pipe a 'suck' just to see what happens...

 

I dont know anyone around here in Wigan or if anyone is local for me to have the Mini plugged into a diags machine... such a shame the Mini doesnt have an OBDII connector as I have the bluetooth adapter for reading and clearing fault codes...

 

Thanks for the suggestions so far folks, really do appreciate it :)

[FlyingScot]

SPi MEMS is pre standardisation so needs a specific code reader; Testbook, Sykes Pickavant ACR or Crypton ACT etc

There is a mini place in Rainford, maybe they can help?

FS

[minisprint]

I've got a snap on scanner does rover spi mpi maybe worth asking local snap on dealer to recommend a garage just an idea

[minisprint]

Remove air box re plug in green air sensor and observe fuel into throttle body from injector should be abe to see if over fueling

[spiguy]

Is the other vac pipe connected - the one which goes from the right hand side (looking from the front) stub at the back of the manifold, and connects to the hot / cold air flap on the air box?  If this is left off / is split / is connected at the back of the manifold but open at the other end (eg if someone has put a K&N cone filter on it but not blocked off the end) then that will cause a big air leak, leaning the mixture. If you leave the ECU vac pipe off, that should cause an over rich condition, as the ECU thinks the lack of manifold vacuum means that the engine is under a heavy load. Just wondering if you have an air leak from the other pipe, which coupled with the over fuelling you get with the ECU pipe off, balances out and lets the run car reasonably OK. If there is a leak at the other pipe, then with the ECU vac pipe on, the fuelling would be very lean indeed.

 

Now, usually with the other vac pipe off (and a big leak introduced) but the ECU vac pipe connected up properly, the idle speed woul be quite high, however it's possible somebody has adjusted the stepper motor idle screw to compensate (assuming my theory about a missing / leaking 'other' vac pipe).

 

Can you confirm the existence / condition / connection status of the other pipe?  (if original it is a Red pipe which goes from the back of the manifold to the air box hot/cold flap valve, then there is a yellow pipe which goes from the other side of the flap valve to the flap actuator on the underside of the air box).

 

Lastly, assuming it is all plumbed in, is there any chance the pipes are swapped on the back of the inlet manifold?  The ECU one (which goes to the fuel trap first as you know) should be on the stub on the left (looking from the front) and the hot/cold flap one should be on the right hand stub (again looking from the front). Not sure, but I had a feeling that one was a restricted pipe stub whilst the other wasn't. Might make a difference.

 

Of course, there are other places that you could get a vacuum leak, such as the breather pipes which connect to the front of the inlet manifold, or even the servo vacuum pipe - that could create quite a big leak, which again I could imagine could be countered by overfuelling by leaving the vac pipe off.

 

Just some thoughts! I can't imagine the car would run very well though in such a situation, but I've never tried it so you never know!

Edited by spiguy, 11 January 2016 - 10:36 PM.

[Black.Ghost]

Don't do it. Injection, when set up, is far nicer - IMHO. There will of course be many on here who hate injection and only want a carb. Although it's only a relatively basic injection system, it's still evolution.

A well set up injection mini is awesome.

[minifreek1]

I will hopefully be taking all the suggestions onboard and having a go at a couple of the theories to sort out my motor...

 

Had a funeral to attend and a few other things that life throws at you to sort, then hopefully will be able to get on with having a play with my motor...

 

Thanks for the help folks :)

[spiguy]

Don't do it. Injection, when set up, is far nicer - IMHO. There will of course be many on here who hate injection and only want a carb. Although it's only a relatively basic injection system, it's still evolution.

A well set up injection mini is awesome.

I agree. Certainly don't give up on it yet. It would be far simpler in overall terms if you can get it sorted out, converting to carbs is technically not allowed for your car and could give issues with MOT / insurance if you have an accident, resale value etc. As Ghost says, if you can get it working I think you would really like it. Apart from being pretty much just turn the key and go, I personally also think they actually drive very well.

[minifreek1]

Righto folks...

 

Had a couple hours spare today so thought Id get meself under the bonnet and have a 'play'.....

 

 

OK - now bare with me on this....

 

Earlier today I heard a metallic rattle, so ran the Mini up on the ramps and propped the rear up with axle stands.... The exhaust was the metallic rattle... so thought it was the catalytic convertor... I had a bypass pipe given to me with a bunch of other spares when i bought the car... so fitted it.... now guess what, it runs fine ..... it revs and pulls like a ruddy freight train... the ECU still isnt connected to the vac system as it should be, it was 1 of my jobs for today but the rattle was my priority... I shall reconnect the ECU tomorrow and see what happens...

 

Maybe the cat was blocked...? but then it wouldnt have passed emissions on its MoT in December, which it passed....