Best Answer madazv8 , 26 May 2023 - 03:25 PM
So an update on this saga. Car is running much better, but I would say still not perfect as reasons below...
After doing everything I could and still not getting to the bottom of this issue, I finally folded and admitted defeat and took the car to the mini specialist. This was after replacing the MAP sensor I wasted as per above and on my other thread about replacing it. It has been an interesting journey of learning and a few times could have led me down some crazy dead ends.
In summary, the car would not idle well. It was clear visually that it was throwing excessive fuel down the intake at idle. Lambda was reading constant high, never went closed loop, and as a result it would only run in limp mode with bugger all power.
So. A day after dropping the car off I get a TXT message with good news. Car is running better.
A spare ECU was plugged in, no change. ECU ruled out.
Confirmed no vacuum leaks. I had gone over this countless times, and was confident that was the case.
Checked fuel pressure. Spot on.
Measured valve lift with a dial gauge. Seems somebody has fitted a high lift CAM ! We know the SPI doesn't like that ! and most likely why I have high MAP reading.
Un-plugged the coolant temp sensor and connected an original Rover item which he had on the shelf.
Place said coolant sensor in a mug of boiled water - immediate difference ! Car idles.
Frustratingly I had ruled out the coolant sensor as it was new, and it also seemed to be working according to MEMS apps. The mechanic has had experience with recent replacement coolant sensors being bad. Even though the readings on the MEMS apps seemed to look realistic, somehow it does not marry up to the ECU. My MAP reading is still too high, and the car bogs a bit at mid range under hard throttle, but that is because of this camshaft. I'll live with that for now.
So lessons learned:
When everything you read says the coolant temp sensor has the biggest effect. Challenge your assumption that yours is ok. Especially if it is a replacement.
The Vacuum gauge diagnosis I talked about earlier in this thread could have had me looking at CAM timing and valve guides etc. These are written for carby engines. Beware.
Don't pull stupid amount of vacuum on your MAP sensor, expensive mistake.
Anyway, It has been an education. Thanks to all who took the time to offer wisdom. I'm off for a 500km drive this weekend :)
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Mini Mad
Posted 22 February 2023 - 01:55 PM
I am running on the basis I did a 500km drive last weekend with extended periods at 4K RPM - then after that when I pulled the spark plugs they were indicating a textbook lean combustion condition (flaky white deposits, no soot). Lambda sensor is saying rich according to the mV output from memsfcr. This to me seems to indicate that the lambda sensor is no good ?
I am just learning the SPI after a couple of weeks of ownership, so happy to be educated if I am way wrong. Cheers.
Mini Mad
Posted 23 February 2023 - 03:05 PM
When the reading for the Lambda sensor is reading high voltage it thinks that the engine is running lean (too much oxygen in the exhaust gas) and therefore increases the amount of fuel supplied. Therefore if the voltage reading goes up and stays high and the lambda circuit is faulty then the engine will run rich (black sooty everything).
If the Lambda reading is low it thinks the engine is running rich (low oxygen in the exhaust gas) and therefore will decrease the fuel supplied. Therefore if the voltage reading goes down and stays low and the lambda circuit is faulty then the engine will run Lean.
So from your description above - if your Lambda reading is low then the symptoms are correct.
If the above statement is correct then test the Lambda sensor as described by yourself in my last post. If you can get the voltage to change then the lambda is ok and it could be ECU (the same as mine). If it doesn't change then make sure the manifold is earthed - The outside casing of the bosch lambda sensor HAS to be earthed for it to work correctly this is done by the manifold being earthed and the by the lambda sensor just being screwed into it. If the earth is ok it could be the Lambda sensor or the wiring somewhere.
You can also find out alot of information from the pinned articles in this section.
Mini Mad
Posted 23 February 2023 - 06:32 PM
Mini Mad
Posted 24 February 2023 - 06:04 PM
Mini Mad
Posted 25 February 2023 - 11:45 AM
I was thinking about this a bit more.
My problem was that the lambda sensor was reading high so reading my running rich correctly and the ecu was not compensating. This was a problem with the ecu.
Your problem seems to be the lambda sensor is reading high too rich and the ecu is compensating which would account for the spark plugs looking as though the engine is running lean. So in your case maybe it is a lambda sensor problem because the ecu is acting correctly?
But I would have thought there would be big performance problems?
Yes there is, it has no power. I am glad you re-visited this, as the conflicting thoughts on what high lambda means was worrying. Thanks.
Changed all my vacuum hoses to 3mm silicone today, and noticed the following. If I remove or pinch the vacuum hose to the ECU the engine does not react at all. Sprayed brake cleaner around the inlet but can't find any sort of vaccum leak. New Bosch lambda coming from UK as I type. I hope that works, but concerned by the lack of response to no vacuum. Bad ECU?.... lets see.
Super Mini Mad
Posted 25 February 2023 - 12:14 PM
Still the same questions! What year is it? Where is the logfile.Until the new lambda probe is there you could bridge the slate wire to earth. then the ecu thinks there is a lambda probe, lambda status will change to 1 (or on ) and ecu should change to closed loop after watertemp is higher than 88 degrees. Test it!
colors of the connector: white, white, black, slate
slate is light green coming from ecu.
Edited by genpop, 25 February 2023 - 12:15 PM.
Mini Mad
Posted 25 February 2023 - 01:11 PM
Still the same questions! What year is it? Where is the logfile.Until the new lambda probe is there you could bridge the slate wire to earth. then the ecu thinks there is a lambda probe, lambda status will change to 1 (or on ) and ecu should change to closed loop after watertemp is higher than 88 degrees. Test it!
colors of the connector: white, white, black, slate
slate is light green coming from ecu.
It is a 94 model (Japanese if that is important). I'll make a log file soon, was busy sorting rear brakes and wheel bearings today. Do I unplug it, and connect slate (light green) to earth as you describe from the factory loom ? I just tried running it with the lambda unplugged after reading some posts on here, made no difference to the idle. Appreciate your input, we'll get to the bottom of this soon I am sure.
Super Mini Mad
Posted 25 February 2023 - 05:01 PM
No do not unplug it. Connect the slate to earth too. And yes it is important.Japanese models have slitely different electric diagrams.
Mini Mad
Posted 26 February 2023 - 09:00 AM
OK, so pulled a couple of logs today. One below operating temp, and one at temp. Vacuum is still reading borderline and fluctuates between error and the top end of ok. It does draw down when I rev the car though. Just found a gauge in the garage I forgot I had. I'll go down and check that shortly. A mentioned I replaced all hoses with high quality silicone vacuum hose (thick walled). See observations in previous post. Lambda status is zero, and closed loop is not happening. See for yourself at the mems analyser page. https://analysis.memsfcr.co.uk/
Logs attached. Change the file extension back to .fcr
Lemme know what anybody thinks. Cheers. With regards to the warmup file, ignore thermostat and battery warnings. I connected on ignition only while the car was at 60deg.
** @genpop Still not done the slate to earth check yet, now I understand what's going on better I'll get into that tomorrow. Standby.
warmup.txt 46.83K
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fulltemp.txt 14.44K
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Edited by madazv8, 26 February 2023 - 09:05 AM.
Super Mini Mad
Posted 26 February 2023 - 06:04 PM
Could you download the mems analyzer from here: https://rmrsoft.com/mems/index.htm
or the mems rosco from github.co/leopoldG
Your logfiles are in hex like the mems analyzer but in a different format. It is very hard to read them with excel or other tools. Memsfcr shows only their analysis not the rest of the logfile.It was easier in his old version 
Mini Mad
Posted 26 February 2023 - 10:35 PM
Would the matching csv file be of any use ?
Edited by madazv8, 26 February 2023 - 10:45 PM.
Super Mini Mad
Posted 27 February 2023 - 11:56 AM
Lets have a look!
Mini Mad
Posted 27 February 2023 - 12:33 PM
Ok no worries, and thanks for taking the time to look. csv file attached - same thing, need to change the .txt file extension back to .csv
So today's update. The new O2 sensor arrived, but before I got stuck into removing the inlet manifold I wanted to double check the vacuum system and see if there was a reason for the weak vacuum on memsfcr, also employed the gauge I mentioned previously. Can't find any visible leaks, as mentioned all the small bore lines are replaced. Larger lines seem to be fine. Sprayed brake cleaner at everything and no engine reaction. Connected the gauge to the vacuum line that connects to to the air filter housing. Reading around 12 in/hg which is low according to my generic gauge tester (dunno what normal is?).
Was too late to start a bigger job, so fitted some T-Handles for the rocker cover, while I was at it I checked the valve clearances, they were pretty good and only slightly adjusted a couple a little. To make things easier to turn the engine over I had removed the plugs... and F me ! what I thought I knew is no longer valid. My deduction that there was a lean condition was after a 250km run at 4K RPM, plugs had some tell tale white flaky deposits at that time. Since then the car has been in the garage, and has only had a couple of round the block runs. Looks like I was way off as the plugs are now looking rich... and they are not evenly dirty. Picture is with plugs in order as facing the engine (No 1 to the right). So just as I thought I was on a good path to diagnosing this I am back to square 1. Anybody got clue as to why the plugs would be worse at #1 side than #4?
fulltemp_csv.txt 32.26K
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plugs.jpg 46.26K
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Super Mini Mad
Posted 27 February 2023 - 01:03 PM
Not what I expected but now you can look to the curves yourselv.
In c:/users/yourname/ you should have a directory memsfcr.Therein is a directory logs.Copy your csv there in.
Now you can read yor logfile within memsfcr.
Of course all lambda readings are bad.Map is still too high, but this may be due to the slightly rich rpm.
Set rpm down to 850 and have a look.
I would use mems-rosco!
Mini Mad
Posted 28 February 2023 - 02:36 PM
Checked all possible places for a vacuum leak once again, nothing obvious. Does anybody have a clue as to why the plugs on 1&2 are so different to 3&4 ? I did the restricting the fuel line test suggested earlier, and O2 sensor didn't react either way?
So now I have ventured into the O2 replacement, and I am half way though removing the inlet manifold to get access to the O2 - tried in vain to get the socket on from above and below. It is quite hilarious how hard it is to do such a simple thing on a mini, I forgot how small they are and most of the times tools are too long to fit etc. Can't say I am confident this is the fix, but lets see. I need that quick release bonnet thing that DHR Garage in Japan show... my scalp will thank me.
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