37 replies to this topic

[funkygibbon]

Ok, i have a 93 SPI Cooper, which i have just rebuilt myself. Engine work was carried by Rob Walker.... However, having finally got the engine to run, it has a really rough idle..... i used to have an 84 City if i pulled the breather off whilst at idle it would rev up and down eventually it would stall. That is the exact problem my cooper has. it starts, rev's up and down, up and down etc... then stalls. i have checked the breathers and all are conected and don't seem to be leaking.. has anyone come across this before? in addition to this it is running really rich! i'm not sure if the two a related but it is begin to really anoy me..... any help would be much appreciated.

[Dan]

It's called induction pulsing and it's a natural effect of engines like the A series (with siamesed ports) when out of tune. I would say that running rich has a bit to do with it, but it's probably just a different symptom of the same problem. What has exactly been done to your engine? Did you just whack the old ECU back onto the reworked motor?

[clubman katie B.F]

talking to a mini mechanic the other day. he had a car with similar problems. if tuning doesn't help then he recomends changing the throttle body, if that doesn't sort it then it could be the dreaded ECU

[funkygibbon]

i only had the crank polished, a very slight over bore and new rings. nothing outrageuos. the head was cleaned, and the old valves relapped. So it should basically be as it was before. yes i put the old ECU back on. i have tried the Rover garage, but to be honest i would have got more sense out of a brick wall..... All the hoses are the old ones, none of the sensors are new. i wanted to get it back on the road and replace the other parts a bit at a time. i have checked the valve clearances, and the compression.... set valves to .35 thou and compression is approx 12bar in each cylinder.

[Sprocket]

Don't go and throw parts at the engine by guesing at it. Eliminate things and deduce the fault. Check every breather hose for wear and cracks including the breathers themselves for oily gloop then check the Vacuum sensing pipes for cracks in the end fittings, they're the ones that come off the back of the throttle body, blow them through as there should be no fuel in these, check them all right up to the ECU, check the fuel trap for the same, finaly Find somewhere to take the car and have it plugged into a diagnostic unit to check all the sensors are working within reasonable limits.

I would say there may be a fault with a sensor, if the ECU was duff then the engine wouldn't run, but if you find the MAP sensor faulty then you will have to renew the ECU as it is built in, electronics are normaly very reliable but are suceptable to moisture and voltage spikes(might be worth checking your voltage regulator on the alternator).

The ECU controls the fueling by comparing the reading from the lambda sensor, manifold vacuum (MAP)and throttle posission to its pre programed tables( this is the bit that can't be altered and where Superchips are taking advantage) after correcting air density by measuring air inlet temp, adjusts the fueling to suit. If any of these sensors are not functioning correctly then the fueling will be incorrect.

Also try powering down the ECU by unplugging it at the main connector for about 30 seconds then plug it back in and start the engine but don't rev it, let it idle for about 10 minuts for the ECU to learn the engine. Another thing I found was the K&N filters are a bugger, if you over tighten the jubalee clip it tends to pull the whole thing up after a time leaving a gap where the injector cable passes through the injector body.

Index the throttle.

Don't go and bin parts without first finding out the cause of the problem, not the symptom. Unfortunately for the ECU sensors you will have to take the car to a garage and have a diagnostics check, but even then you probibly know more about your engine than they do, so you will have to take the information ( not the mechanics opinion unless he can prove with out a doubt)and work it out yourself, like I said unfortunately you'll have to do this to get the information. I found mechanics that don't know you or the car to be a bit funny, they think you know less than them because you have taken your car to them to fix. I find this is happening more and more these days, thats why I choose to do virtualy everything myself when I can.

I found out some of this as I this week had similar problems, eratic idle, stalling on cold start idle and get this, backfiring into the inlet manifold. I found the problem to be fuel in the vacuum sensing pipe Connected to the ECU at the ECU end, this obviously was causing inacurate MAP readings. I had the whole injection system apart and found nothing else, powered the ECU down and restarted and everything's now fine.

Hope some of this may be of help.

[funkygibbon]

wow, ok that's really cool. i am going to check everything this weekend to see if i can find anything.. as far as the MAP sensor goes, i have an SPI injection system which seems to be slighly different from the MPI and my MAP sensor is clipped to the side of the inlet manifold...

I was reading my Haynes manual earlier and noticed that the Flywheel obviuosly has magnets attached to it but more importantly has a magnet missing at 0 and 180 degrees so the ECU knows when the engine is at TDC.......

Should the flywheel be in a certain place when it's put back on the car? it doesn't actually tell you in the manual to set the engine to TDC and put the flywheel in at a certain point, but this would seem like a fundimental thing? otherwise the ECU surely will surely get a wrong signal!

[Sprocket]

Are you not getting confused with the fuel trap which is mounted to the left of the manifold, or the throttle possision sensor on the left of the throttle. The map sensor is part of the ECU to prevent any sort of interference with the signal if it were mounted externaly. the fuel trap is a black rectangular box with a black inlet stub and a shorter green outlet stub. The manifold vacuum is connected to the black stub of the fuel trap then from the green stub on the fuel trap to the stub on the ECU, this stub is behind the main wiring connector as you look at it from the front of the car. The device on the right of the manifold is the stepper motor for idle control.

If the ECU is not connected to the manafold vacuum then this is the fault.

As for the flywheel, theyre not magnets they are high spots cast into the metal at time of manufacture. The crank possision sensor is called a Reluctor, there is a coil of wire with current passing through it, as one of those 34 high points passes the sensor the current changes giving a pulsing current that the ECU can read, the two missing high spots equate to TDC and BDC on No 1 cylinder and the ECU would see something like this ----------------- ----------------- ----------------- and so on. The sensor fits in the flywheel housing and shouldnt move, the flywheel can only go on one way located by the locating washer.

I do believe however that there is some incompatable parts around, this was extracted from the Mini Spares Center web site "Flywheel Part No. C-AEG423 - With AP pressure plate This flywheel must use a genuine AP CLUTCH PRESSURE HE3864 (GCC679)or Genuine AP clutch(our own GCK151AF)or the car WILL NOT START because the timing slot is out .USE C-AHT596 WITH CORRECT PRESSURE FOR BEST CLUTCH AVAILABLE ON VERTO MINIS this has 2 timing oval holes. Do not try to fit anything other than the genuine AP clutch and beware of Unipart supplies because under GCK151AF they are also using valeo pressures which will work " I don't realy know what they are going on about but some one on here might

I may be wrong but i thought all spi systems are the same, i'm intregued. let me know the out come as this is my own first SPI and i'm curious to know more as no dout are you

Think I should start a thread called Fuel injection explaind, though I'm no expert.

[ed4ran]

Strangly my brothers 92 SPI was acting like this (about January) , running rich (lots of soot), and lumpy idle. then it got to the point where it wouldnt start!!! so we towed it down the road to a friendly garage, he changed the spark plugs :nugget: and said that it will happen again because he only got it running, but he couldn't find anything wrong within his capabilities as it was beyond his tools (he dont have all the sensor testors etc) but he recommended a place that was specifically for testing and tuning, so we took it there while it still worked.
Picked it up next day running sweet, they said it had bad vaccum/ few gas leaks, they changed a few pipes n stuff, and then gave it a tune, and it still works well. They said though that it will need a few hundred miles to remove the C**p that had built up.

Then my brother goes and crashes it a few weeks later!!! :nugget: but this weekend it should be road worthy again (will just need MOT, windscreen and TAX)!

[funkygibbon]

I think someone should definatley right an article, "Mini Injection Systems For Dummy's" i would buy it...... lol. i may well be confused Mini Sprocket, and believe me it doesn't take much at the moment. My haynes manual said that little black box was the Manifold Absoulte Pressure (MAP)/ Fule trap that's were my information cam from... so reading between the lines. the flywheel shoud go back in such a way that a high spot is at the sensor when the engine is at TDC? i got my clutch kit from mini spares its a Délphi Borg & Beck on!! the flywheel is the original just balanced with the new pressure plate.
The only reason i thought SPI's and MPI's were different is because i read somewhere that MPI's have cam phase sensors which were mounted in the old fuel pump hole on the back of the block, mini doesn't have that, therefore stupid assumption that MPI's might work in a different way with a few extra sensors.... then again i may also have got the wrong end of the stick on that one.......

[Guess-Works.com]

Mini injection system for dummies ( aka me )

Rip out anything to do with the injection system and replace with a carb ! :cheese:

Only kidding, IMO, injection = voodoo black magic.

[psycho mini driver]

i had this problem, tried everything, the last thing i tried solved it. it was simply the vacume hoses on the back of the inlet manifold. i reguarly checked mine, perhaps once a month as they reguarly broke or coroded. what happens is the ecu thinks there isn't enough air, so compensates with fule. check it tonight, takes all of 10mins. its a *Female doggy* to get to, but they are there, tucked well away!

[funkygibbon]

NNNNNNNNNNNOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO. took all the vac lines off today. blew them through with the air gun... didn't seem to be much in there. fitted them again. Problem is still there.... i really have no idea what to do. i think i have checked everything apart from having it plugged into fault reader to see if there is something wrong. i have found a round plug socket with a cover by the pump relays, is that were the fault reader plugs in? has anyone had there's checked? if so how much do the useless gits charge you for the privalege??

[Sprocket]

Found this, just out of interest.

http://www.picotech....bda_sensor.html

http://www.cats-dire...ring-advice.php

[psycho mini driver]

were the rubber elbows that hold the plastic pipes taken off and checked? this is what broke on mine

[funkygibbon]

Yeah, i had the whole lot off. one of them wasn't a very tight fit so i wrapped electrical tape around it to make it air tight just in case... i haven't reset the stepper motor yet which you need to do when reconnecting the accelerator cable. do you think that could have some thing to do with it????