156 replies to this topic

[gdudu]

Hi , thanks for the detailed response, t very comprehensive for me, but very bad for me also :-(

I am very diapointed if all seem to be normal

I will try to mesure fuel pressure, if someone know the good value for a mini SPI ?

Does someone know where is this fuel regulator ?

Cause I've changed 2 years ago, all the injector with stepper motor and all around, cause I thought that was the problem of my consumption. But not this is the same, then I thought it was a sensor somewhere else.

[Sprocket]

What stands out is Idle speed is low. What is ignition advance at idle? And stepper position at idle?

Throttle position reading should not fluctuate with zero throttle movement. Acceleration enrichment is added based on the rate of throttle opening (degree over time) so if the reading is jumping around acceleration enrichment will be added unnecessarily. Is there any data for acceleration enrichment?

Mentioned earlier, the purge solenoid, if stuck open will draw air and fuel in from the charcoal canister under the right side wing. It is surprising how much fuel is drawn into the engine from there!

Other possibilities..... fuel pressure regulator higher than normal fuel pressure. Check fuel return line to tank under the car for crush on metal pipe or kink on rubber hose engine bay and boot.

How much history do you know of the car?

[gdudu]

Hi

I have buy the car 3 years ago. It was refused to technical control, and I buy it for nothing.

I changed the differents vacuum pipes, coolant temperature sensor, sparks plugs, air filter, and the technical control was OK

Last year, I changed all the injector bloc (with another old one), cause I thougth it was the reason of my consumption, but this was the same

 

That's all what I know of the car.

 

I have to say this is my (my wife) 5° austin mini. All the previous models I had were older, with carburation.

This one is the best I never had, and it work prefectly, start easy, powerful and speedy. Except technical control and consumption, and a big black smoke at starting, but start very well.

 

Here are the graphs for Throttle at 2500 rpm, it seem normal (stable)

Iddle igniton advance is equal to 12° on MemsAnalyser

ECU fuel loop status is always closed when motor is on, it"s off when motor stopped on MemsAnalyser

 

For the purge solenoid, I don't know what it is ??

Attached Files

•  Speed iddle Throttle.png   172.75K   2 downloads

Edited by gdudu, 15 March 2018 - 08:52 AM.

[Sprocket]

This is the purge solenoid.

[martinrub]

Purge valve from Haynes Chapter 14 (MEMS):

“ACFSV and activated carbon canister will also be employed to aid evaporative emission control (see illustration 14.7). The carbon canister stores fuel vapours until the CFSV is actuated by MEMS.CFSV actuation occurs when the engine temperature is above 70°C, the engine speed above 1500 rpm and the MAPsensor returns less than 30 kPa.
When the CFSV is actuated by MEMS,the valveis modulated on and off,and fuelvapours are drawn into the inlet manifoldto be bumt by the engine during normal combustion. So that engine performance will not be affected, the CFSV remains closed during cold engine operation and also during engine idle.” Your logfile shows correct commands from MEMS to the carbon cannister, but of course that does not mean that the valve is reacting properly to those commands.

With a hand vacuum pump you could check the valve is closed at engine off. Or, if you don’t have such a tool, you could block (without damage) the vacuum pipe leading to the canister and see if that makes a difference to the black smoke and short term fuel trim.


The black smoke on starting and the “start easy, powerful and speedy” will be because it is running very rich and for the first minute or so in Open Loop. Your logfiles appear to show that in closed loop, MEMS is correctly controlling the fuelling but is having to subtract a fair amount of fuel to do so (-12%).




You only see black smoke when starting? After a long drive with a hot engine, are your spark plugs are a normal (not black) colour?


Is it possible that an incorrect model of MEMS was fitted? There will be a number on the MEMS unit beginning with MNE (I think). Perhaps you can post it so people can confirm you have the correct MEMS unit?

It would be useful to see a logfile beginning with when the car is cold. Could you produce a 15 -25 minute logfile making sure it begins before you start up from cold and drive until the car has reached normal operating temperature, with a mixture of driving on local roads and some motorway driving at more than say 80km/hr?


One thing still puzzles me: it appears, from your logfiles, that the car is running in closed loop most of the time, keeping the mixture at the correct level (but having to keep a -12% short term fuel trim to do so). So I wonder why the consumption is so bad. That’s why I like to see a logfile from cold.


It would be very useful to do a compression test on all 4 cylinders. (Hot engine, plugs out, throttle fully open, injector disconnected.). If you film the gauge with your phone as you do each test, you will be able to study it later - very useful, indeed: it will show the quality of the compressions eg how many compressions to reach the final value etc.

(And if you don’t know the history, and haven’t already done so, you will want to replace the timing belt, tensioner (and water pump if it is driven by the timing belt). Even if you don’t do that immediately, there is no harm in inspecting the belt for wear and making sure the timing marks line up correctly.

So to start with, a long logfile from cold?

[genpop]

try this software.:https://github.com/LeopoldG/mems-rosco

[martinrub]

I forgot: when I wrote about doing a compression test-

It would be very useful to do a compression test on all 4 cylinders. (Hot engine, plugs out, throttle fully open, injector disconnected.).

I should have added: disconnect the low tension side of the coil. With spark plugs removed, you dont want it generating HT with nowhere to go.

[gdudu]

Hi

I have made a new recoding data with readmems.exe, during 14 mins

The first half is starting, with cold motor, and the second half is on roadway, between 70 and 90 km/h

I think I have a problem with intake air temp, and the cooling liquid is not very hot (68°C max), I don't know if it is sufficient for explaining my problems

 

I will try to find a garage to make a compression test next week

Attached Files

•  Cold start and roadway 5mn.txt   386.32K   7 downloads

[martinrub]

Thank you. I will look at your logfile and get back later.

As for going to a garage for your compression test, why not buy a compression gauge kit; Im sure it would cost about the same if not less than a garage would charge, and you would have it for future use. On Ebay and Amazon for less than Euro25 I dont know how good they are, but you could have a read of user reviews on Amazon.

Edited by martinrub, 25 February 2018 - 05:53 AM.

[martinrub]

You started logging with the engine running; I had hoped you would start the logging and then turn on your engine, because I noticed something wrong but I would like a bit more evidence.   
 
1.   The engine is not running between 0.6 min and 1.3 min, but the oxygen sensor is still reporting 0.8 V.        This is not normal: with the engine not running the lambda voltage should drop to 0.45V.     This is the bias voltage: a voltage produced by MEMS which it uses to test/monitor the oxygen-sensor circuit.
 
2.    So I looked at your "Motor stopped for throttle" logfile.    Your lambda voltage is zero.    It should read 0.45V - the bias voltage.     This means that either there is a short in the oxygen-sensor circuit or the bias voltage is absent.   
 
I don't know what level of testing you are comfortable with and what equipment you have.    But to test for bias voltage you would disconnect the lambda sensor and measure the voltage with a good (very high impedance) voltmeter at the lambda connector (the connector that leads to the ECU), measuring across the signal wire and the signal return (ie the 2 wires that are NOT hte heater wires).     With the ignition on you would see perhaps 0.3 to 0.45V depending on hw good the volmeter is.    I feel fairly sure there will be a voltage and that the problem is in the oxygen sensor itself.
 
if the circuit was working correctly, you would see 0.45V on your logfile with the engine not running and then when you start up, for the first minute or so you would still see 0.45V until the oxygen sensor starts to warm up and then that 0.45V line would either start to fall or start o rise as the sensor starts to switch.     

 

(One thing is puzzling me a little, I think: I had thought that if MEMS did't see the bias voltage, it would not go into Closed Loop, but when I think about it, what I remember is that if the bias voltage of 0.45 did not drop to zero in a certain time, it would not go into Closed Loop.    So as the bias voltage is showing zero, maybe that explains why it does enter Closed Loop.    Even so, a bias voltage of zero at startup ought to tell MEMS that something is wrong.)
 
(I would include images except getting them on is  too problematic.)
 
But seeing that you get a rich signal when the engine was off in "Cold start and roadway" for half a minute, my guess is there is nothing wrong with the bias voltage signal from MEMS, and that your oxygen sensor is faulty.      There could be further tests to prove that.   But, if the oxygen sensor is faulty, the reason needs to be found, or you could fit a new on and the same thing would happen.      Do you have a head gasket failure; has coolant poisoned the sensor?       If you were going to take the car to a garage for anything, then a test for hydrocarbons in the coolant would be a good idea.    Are you loosing coolant, even a small amount?
 
A good garage could put its exhaust gas anaylser into the opening of your coolant expansion bottle and measure for hydrocarbons to see if you have a head gasket failure.      Coolant in the exhaust will pioson the sensor.
 
 
Until then, perhaps you might want to generate another logfile, start the logging BEFORE you start the (cold) engine - and then let's have another look at the oxygen sensor output.    As I have said, you should see 0.45V from when you turn on the ignition until perhaps a minute late when the sensor starts to switch.
 
 
(One other thing for when it's fixed: you must change the engine oil: it will be contaminated with fuel and you could get readings that look odd eg still appeating to be rich, when in fact it's petrol coming out of the oil.)

Edited by martinrub, 25 February 2018 - 08:13 AM.

[martinrub]

I addition to the logfile I mentioned in the previous post - from ignition on before startup, cold engine - theres another logfile that might prove useful.


With a hot engine at idle, remove a large vacuum pipe (NOT. the one to MEMS!) - perhaps the one to the carbon canister/purge valve. The pipe should be latge enough to cause an instant drop in RPM (but not stall). Leave it off for at leadt 3 full minutes - long enough for MEMS to correct the sudden lean condition. Then put the pipe back - still logging, engine still running, the RPM should increase, keep logging for another 3 full minutes, stop the engine, put the ignition back on for half a minute (lets see the bias voltage) and then stop logging.

That would show us how quickly and how well the 02 sensor reacts to avsudden change in mixture.

[gdudu]

 Hi,

 

Thanks again, very instructive

 

I've made a cold start and leave the motor heat at iddle during 11 minutes. The lambda seem OK, I'm very disapointed

 

When the lambda start to switch, the STFT start to say "too rich" and give less. Less and less as the motor heat. Don't know if it is normal

 

I've made the second test. But when at 00:01 minute I removed the carbon canister pipe, no drop in RPM, it was exactely the same

This is timing for this record :

00:00 = start motor

00:01  = remove the carbon canister tube

00:03 = a little acceleration

00:04  = put back the carbon canister tube

00:07 = stop motor

00:09 = stop recording

 

The STFT seem not to change during this test, no specific thing at 00:04

 

 

 

Attached Files

•  Test removing big tube STFT.png   241.04K   2 downloads
•  Cold start.txt   288.45K   3 downloads
•  Iddle with without carbon canister tube.txt   240.26K   2 downloads

[gdudu]

As for going to a garage for your compression test, why not buy a compression gauge kit; Im sure it would cost about the same if not less than a garage would charge, and you would have it for future use. On Ebay and Amazon for less than Euro25 I dont know how good they are, but you could have a read of user reviews on Amazon.

 

I've buy a compression test kit on eBay, but this will be in 3 or 4 weeks

I don't excactely how to do, but I will find

 

Thanks for the info

Edited by gdudu, 25 February 2018 - 12:53 PM.

[martinrub]

Many thanks.   Very interesting.

 

 

Cold start:

 

1.    This time you do have a bias voltage.       But we cannot dismiss the fact that it was zero on your Motor stopped for throttle logfile.

 

2.     Nearly 3 minutes to go into closed loop?    I don't know - it might be normal for the Mini, I doubt it - that seems very slow.

 

3.     Look at STFT: it starts off good, especially between 4 - 5 mins.    It's close to zero and narrow banded.   But look how it drifts dowm after 8 mins and starts to fluctuate over a much wider range.   This is really interesting.    it means the mixture appears to get richer as the car warms up.      The purge valve is not commanded open during this time.      So this makes me think that Leopold's suggestion (to me in an email) may be right: could the purge valve be stuck open?

 

4.    The sensor is switching about 20 times a minute at idle.    On your 2500 rpm logfile it was much faster, as you would perhaps expect.     But given it takes nearly 3 mins to go into closed loop and this low switching at idle, you really ought to check the oxygen sensor heater is working.        When you disconnect the oxygen sensor the 2 wires with the same colour (on the sensor side of the connection) are the heater wires.      If you measure the resistance you should get perhaps less than 10 Ohms; whatever it is, it must not be OL (open circuit) - be careful, do not damage the pins or females in the connector when testing     When I first looked at your lambda graph it looked - to me - as if your heater was working, but that's pure speculation.    There is no substitute for properly testing it.

 

 

Idle without Carbon Canister

 

Again interesting.      

 

1.    No sign of any change in maifold pressure or RPM when you take it oof or put it back.    Interesting, perhaps too low an airflow in, still a bit odd.

2.    On the Full Trip scale, look how STFT starts to climb after you took the pipe off - this means MEMS has reduced the amount of fuel it is taking away.   In other words, the mixture is getting leaner (less rich with time).    Now look what happens when you put the pipe back:STFT shows the mixture slowly gets richer over the next 3 minutes.     So something was going on during that test when you disconnected the canister.     Again, this suggests that possibly the purge valve might be stuck open and that further investigatioin to check this is required.      Whatever it is, the cahnge was not instantaaneous as you might expect, especially pulling it off.

 

 

 

 

So, if at all possible:

 

a.  Test the resistance of the 02 sensor heater.   I'm not yet convinced the 02 sensor circuit is perfect.

 

b.   Take off that vacuum pipe to the carbon cannister again and this time seal it up with tape or block it and let's see some logfiles of your driving the car with the pipe sealed and not connected to the canister      I would also leave that pipe blocked for the moment and see if the car behaves any better over the next few days.   But remember that your oil may contribute to making things slightly richer than they should be.      Again start all logfiles with the ignition on but the engine stopped, and when you finish, stop the engine and put the ignition back on for a minute and then stop logging.        I'm still thinking about that lack of bias voltage on your throttle ogfile.

 

 

And what about coolant - are you getting any coolant loss?     Do you have to keep topping it up, even by a small amount?

[martinrub]

 

As for going to a garage for your compression test, why not buy a compression gauge kit; Im sure it would cost about the same if not less than a garage would charge, and you would have it for future use. On Ebay and Amazon for less than Euro25 I dont know how good they are, but you could have a read of user reviews on Amazon.

 

I've buy a compression test kit on eBay, but this will be in 3 or 4 weeks

I don't excactely how to do, but I will find

 

Thanks for the info

 

That's good.    None of us knew how to use it the first time!    With some practice you soon will know.   They normally come with good instructions and you have 3/4 weeks to look on the Internet and try to find a good YouTube video (good luck there!)     And people here will guide you...   Just remember:

 

Hot engine, plugs out, throttle fully open, injector disconnected, and coil (low tension side) either disconnected or make sure the spark is discharged to earth ot both!     (Keep any spark discharge away from MEMS make sure it discharges to earth: don't leave it to find its own way out - hence disconnect the coil Low Tension side!)

Edited by martinrub, 25 February 2018 - 02:43 PM.