29 replies to this topic

[FlyingScot]

What year of SPi ? Does it have the throttle switch fitted? If so check it's working.

FS

[Mini_tommy]

Hi. Thanks for the info chrome, will definately give that a check, clean up, lube, and refit. The popping also happens when fut flat down on the throttle trying to pick up speed, but guess the tps still could be at fault as the fuelling would still be off if its sticking. However in saying that, it does pop when slowing down too.

 

The fuel filter is definately on my list of things to try, gonna try and get a day of working on it this week.

 

The car is a 1996 or 97, cant remember but its a P reg, and does not have the pedal switch as far as i am aware because its only got the one multiplug to the ecu, and ive taken a look, and cant see any throttle pedal switch at the pedal, so guess it relies just on the tps sensor.

 

When changing the vacuum pipes I was over the moon when i found two were damaged as thought it would have solved it, but unfortunately it didn't just improved it a small amount.

 

Once resolved I will keep updated incase it helps anyone else. Thanks for the advice so far

[Phil-R]

I really hope you have some luck with this - These injection models are a pain to diagnose, so I feel for you.

 

Regarding the low idle speed, there could be any number of causes, but have you confirmed the stepper motor is working and has been reset? This is an easy place to start:

 

If you don't already know, reset it by turning the ignition to the on position then stamping on the throttle pedal 5 or 6 times so that it fully opens and closes the throttle several time. You should hear the stepper motor trying to find the closed position then moving the throttle to the start position. If you don't hear it, take the air filter lid off, turn the ignition off and on again, then, from under the bonnet , open and close the throttle (fully) several times and look for any signs of life. Note that this relies on the throttle position sensor, but is no guarantee that the sensor is working fully (i.e. sticking as mentioned before).

 

As the car hasn't been used for several years, have you had a chance to put fresh fuel in the tank? Fuel goes stale in a lot less time than 6 years

 

One last thought for tonight...  The ECU can make a mess of the fuelling when the water temperature sensor isn't working correctly. The ECU relays the temperature to the dashboard so keep an eye on it when it misbehaves and check it stays around the midpoint. I've had some symptoms like yours when the manifold waterways ( that contain the temp sensor) were silted up.

 

Good luck chap.

[Mini_tommy]

many thanks for the replys.

Yeah ive ran about £25 of fresh fuel through it, buy admitedly i ran the old fuel through it fiirst, hence why I think it is detromental i replace the fuel filter. I have tried resetting the stepper motor, I do hear it working, but have never actually looked to see it working. As I have a flip front I can look at the stepper motor quite easy without taking the air box off, so will check it visually next time i work on it.

 

I have thought about the engine coolant temp sensor, It sits about halfway between the first line and the midway line when sat idling on the drive, and when started from cold, displays as cold too, so think that the ect sensor is working, but I was thinking of biting the bullet and replacing the air, coolant sensors, lambda sensor, and doing the advice above. Also a coolant flush ran through the system too.

 

My diagnostic scanner works for fault code reading, but when trying to read live data it seems to allow me to view it for a second then looses connection, till i re click back into live data and then i get to view it for a second again, so this is really making it hard for me to check the sensors etc. Gonna give it another go though, and check that the map sensor faults now gone since replacing the split vacuum pipes. If it hasn't then looks like i need a new ecu for the sake of the map sensor. With mine having the immobiliser and fob etc, what are my options to replace the ecu? a second hand set with fob, ecu and immobiliser? or can you get virginised ecu's that have the immobiliser removed from them?

[FlyingScot]

Tricky if your code reader isn't working fully. Are you taking the power from the starter motor terminal or battery positive?
The ECU is pretty robust and if you come to the conclusion it is it I would get it checked/repaired as the alarm box is coded to the ECU and the alarm to the keyfob so it isn't an easy option to change one part as you surmised.

FS

[Phil-R]

See what you're code reader says now (do you have to clear the faults manually?) Then unplug each of the sensors on by one and see what changes. Coolant, TPS, and map sensors each have a big effect on the how well the engine runs. Air temp and lambda sensors make such a small difference while driving, you will barely notice if they were even unplugged.

 

Is the scanner yours or did you borrow it? There's a manual here that shows Rover specific menus and settings. It even seems to let you change the BAUD to alter the data transmission rate... something that would cause communication problems if set wrongly, so perhaps worth a read and playing with the settings.

http://www.snapontoo...tors_Manual.pdf

 

You're best bet is getting the scanner working but in case you can't, do you have a digital volt meter? All the sensors above can be tested with one, and may be the next step if you're code reader is showing you all that you need to know. If you're willing, then let me know and we can compare readings with my sensors.

 

Don't go and buy a load of sensors - you will likey be disappointed.  I did this and even bought another Rover MEMS (non mini) and swapped over the map sensor. I spent quite a few quid doing all of this because I didn't test them properly (It was the slightly sticky TPS sensor that got me)

[Mini_tommy]

The scanner is mine, it is a Snap On Ethos, but I have the adaptors for all the manufacturer specific ports prior to obdII. Yeah I know the immobiliser and fob is coded to the ecu, but was wondering if theres any companies that sell ecu's that do away with the immobiliser (re map them out sort of so to speak). I was taking the connection from the Battery Terminal, I shall try it from the Starter Motor terminal to see if it makes any difference.

 

I will certainly check the baud settings and thanks for the link. I do have a digital volt meter so some data to compare readings with would be fantastic if you don't mind. Im hoping possibly thursday or the weekend to get working on it again. I am certainly going to check the fault codes again, clear and re run the mini with the new vacuum pipes and re check the codes, and fingers crossed the map sensor fault code isnt there.

 

Anyone recommend a specific brand of coolant flush, or is the likes of wynns etc good enough?

 

 

Oh I tried to use some electrical contact cleaner on the tip of the air temp sensor, and the air temp valve thing, and that didnt seem to make any difference.

 

Thanks for the replys both.

Edited by Mini_tommy, 07 October 2014 - 10:39 PM.

[Phil-R]

I would bet most coolant flushes use similar chemicals and are as effective as each other. After it's had time to soften any crud and you've flushed it, also back flush the heater matrix and inlet manifold separately. This is easy to do; Look at the hoses to the right of the manifold, behind the thermostat. Some of the hoses feed both the heater and manifold. If you try to flush through both at the same time, you won't clear any blockages, so undo the connectors such that you can push a garden hose up to them and force water through the inlet and heater matrix individually. 

 

Good luck with the scanner. Don't forget, you may need to clear the MAP fault manually -I'm not sure how long it would take to come back up, but fingers crossed you've sorted it with the vac pipes.

 

I'll keep an eye out for you updates.

[Mini_tommy]

 photo.JPG   29.96K   6 downloads

 

Ok bit of an update...

No Fault Codes Present so the map sensor fault code was due to the split vacuum pipes. So thats sorted, but the mini still feels like crap.

 

I have replaced the fuel filter (what a pain) it now has a standard fuel filter (same size and shape as original) but with fuel injection hose direct from the tank to the filter, then the bendy metal part after the filter to the hard fuel line is also hose.

 

The mini is still acting exactly the same but now it doesnt cut out at all since sorting the vac hoses.

 

Lack of power, and backfiring in the exhaust (popping) mainly when deaccelerating or if the car isnt going fast enough and you gear up it backfires and splutters (got to stay in lower gears longer or splutters). Cant think of going into 4th gear unless im at 50mph or it just splutters and shakes.

 

I have removed the TPS as suggested, but to be honest it was moving freely, but have cleaned it and put it back on, but hasn't made a difference.

 

Unfortunately it doesnt look like i can change the Baud rate on my scanner, so i cant monitor the live data very easily, as it cuts out after a few seconds and have to press reconnect. I have attached a screenshot of the scanner at idle, what you all reckon? anything look a drift? The light has made it a bit difficult for the screenshot of the scanner, but the readings are as follows:

 

Engine Speed (rpm) : 832

o2 Sensor (mv) : 458

Battery (v) : 13.7

Throttle Valve Position SNS (v) : 0.64

Coolant Temperature (oC) : 71

Intake Air Temperature (oC) : 33

MAP (mbar) : 460

Stepper Motor Position : 85

 

Now as I was saying the live data feed cuts out every few seconds so couldnt monitor it very well, but each time I monitored it, the o2 sensor never flickered to -mv it was always around 458mv. The other thing is the Intake Air Temperature sensor showing 33 degrees celcius. Now to me that reading seems quite high considering it was probably about 16 degrees celcius outside today. Obviously there will be heat from the engine etc too, but its got a flip front, and at the time of using the diagnostic it was flipped forward, so wasnt being cooked up.

 

Im thinking of replacing the air temp sensor and the lambda sensor.

 

I also decided to take the air filter housing lid off and watch the injector at idle etc. if i rev the car the fuelling increases, and when I leave off the throttle and shut the throttle valve its still fuelling (less, but still making the butterfly valve and surrounding area wet with fuel. Guessing this is why im getting the popping noise in the exhaust. Also without revving, the butterfly valve seems quite wet with fuel, but never seen another mini fuelling to compare with, anyone have a video of theres ?

 

Finally should there be any voltage output reading for the throttle valve position when idling and not touching the pedal? Or is it because the stepper motor is holding the throttle open ever so slightly which is giving the 0.64 v reading from the tps? the voltage does increase as the revs increase.

 

At idle, the car revs up freely, and sounds like there plenty power. It does seem like its only when theres a load on the engine when it has the problems.

 

Any suggestions welcome :)

 

Thanks for the help so far :)

Edited by Mini_tommy, 18 October 2014 - 08:00 PM.

[Fast Ivan]

the lambda should fluctuate from high to low rapidly, if its not doing this then its suspect

the IAT, I assume that the reading above was taken when the car had been running a while? what was this showing when you first stated the car? has it increased in temperature basically

the TPS showing 0.64v I think is ok, pretty sure it should be between 0-1v

the thing you need to do next is to test if the sensors are working as they should;

the MAP reading looks about right, does it increase with revs? what does it read at full open throttle?

does the TPS voltage increase as you put your foot to the floor?

as with the IAT, the CT should start cool and increase in value as the engine warms

[Mini_tommy]

Hi,

the TPS voltage did increase as I was increasing throttle, thanks for verifying that there should be low voltage at idle.

Yes the IAT reading was took after the car was driven, but didn't take it before hand. Still seems a bit high considering the ambient air temperature was only 16 degrees roughly, so for the price of them might replace it.

 

The CT Sensor did read lower after the car had been left for a bit and i took another reading, and the guage seems to act normal too, so guessing this is ok.

 

Im wondering if theres a chance my valve timing is out, and maybes the chain has stretched or jumped a link or something due to starting the engine up after leaving it for so long (about 5-6 years).

 

Im going to do a compression test next, just to rule out the above and any possible other engine wear & tear. If compression test comes back ok, then lambda and IAT it is.

[FlyingScot]

Throttle position is off... TPS reading is highish I would expect 0.4 to 0.5 volts at idle when warm.
Number of steps on stepper motor is also high I would expect much less say 45 steps.
As Rob has made mention of above Lambda should be switching constantly ( they slow down as they age )
Check throttle cable is free to move and "lost linkage motion" is in the middle

FS

[Mini_tommy]

thanks for replys both.

could the throttle position be showing slightly high, due to the stepper motor being out too much? I don't understand how it could be out as it was running great before it stood, and I havent messed on with the adjuster screw or anything. yeah the throttle cable moves freely, ive lubricated it all too. The lost linkage motion i would say is out, but only just, talking say 1mm if that off center. would you think that would cause all these problems?

[Phil-R]

Can you run the diagnostics with the engine off? ...Just in case there's some electrical noise that's causing you problems. If so, check the TPS live data while moving the butterfly via the throttle linkages and make sure it can read voltage changes just a fraction off idle.

 

TPS is what caught me out as the voltage was believable, but it got stuck a fraction from the closed position so gave the ECU a low voltage very close to what it should have been.

Edited by chrome, 19 October 2014 - 11:42 PM.

[Phil-R]

From the MEMs manual :

 

http://www.renegadem...y/RoverMEMS.pdf

 

 

"From the voltage returned, the ECM is able

to calculate just how quickly the throttle is

opened. From model year 1993 onwards, the

TPS also informs the ECM of idle position with

a voltage of approximately 0.6 volts"

 

 

I'd still say your voltage of 0.64 volts is  borderline, so worth trying to get a proper data stream out of the diagnostics. Or failing that, tap a wire onto the TPS connectors centre pin and get read it directly with a volt meter