when its on idle its running open loop, when rev it ecu switches to closed loop hence why triggers when rev it, would need to know volt\age from signal wire,, ie should be switching from 0.1 to 1v volt ish,, and when hot ie exhaust 600c they make a voltage,, also would need to scan it with a diagnostics tool that sees all the codes a must, also live data see if it a reactive fault from mechanical issues or a ecu or harness intermittent fault perhaps pain in arse fault

 

Good points all. I’ll upload photos from the scanner shortly. It does show a pretty steady .46 volts. Has shown a p0136 but has not shown that recently after clearing.

 

that p0136 shows a circuit problem, the ntk sensors are hmmm put it this way I have fitted many hundreds of them over the years and not bought a bad new one yet, where borsch ones have had new ones ones faulty before. hence why when i refresh these engines i only fit ntk sensors over the counter not off online stores to ensure i'm getting genuine ones, to many fake ones around , 0.46volt says it running it should be changing as car is rev'd and not constant at that voltage

 

Yeah the voltage is staying pretty constant. Where do you source your NTK sensors to make sure they are legit? I may just need a different sensor.

 

we have company here called motorparts direct I have one near where I live and only ever buy over the counter, i see your issue with where you come from and getting known genuine sensor,, you might need a visit to bmw/mini dealership in your country,
have found these form states

Oxygen Sensor-OE Type NTK 25648 fits 02-08 Mini Cooper 1.6L-L4 | eBay

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worth writing to them and ask if they have right one with your reg number etc, heads up the 02 sensors and cat should be treated as one unit,, ie they last around 80k and should be replaced together for best outcome, these engines are living on knife edge as run to 112c temps at peak with fan on so always run risks of lean out and lean outs with destroy them over time as combustion process gets so much hotter ,, to point that when 02 sensors and stretched chains cause lean out running it also melts the valve stem seals on exhaust side and all the engines i have rebuilt suffer from piston rings gone brittle and baked carbon on the rings adding to the oil use and wear on them,

 

By the way here is what my reader showed.

 

below pic of n12 b16 engine same on them all in fact of resistances

below pinout ecu plus values and when

 

Oooh. That’s very helpful. I’ll go through this over the weekend. Much appreciated.
cheers sir

 

One more quick question, just realized as I was reading through the images you sent. How am I supposed to check voltages at the ECU with the engine running??

 

if you look at the pics its says if running or just ignition on in one of the boxes,, you always probe a completed circuit so plugged in ,, can run small needles in to rear of the plugs or what i use is safety pins as cheap and if loose any it dont matter ,,just be careful not to touch them together as could spike ecu then its a whole world of hurt

 

4th box across tells you idling or ignition on etc

 

Ok so finally getting back to this after a work break. Quick question, is that down stream sensor a narrow band sensor? If so what is the healthy range of voltage off the signal wire on a good sensor with a good cat? Any idea? I know it ranges from .1 to 1v but is there a healthy number at the max voltage when reving the engine?

 

0.7v is mid range where they sit on a healthy engine

 

Got it. .7 v is the healthy spot. So I’m thinking about just putting in an O2 simulator to get past emissions instead of throwing another 250 sensor into it. Seems more of a sure fix and cheaper. I’ll let you know how it goes.

 

what happens on all these engines with age and miles is because they use to much oil the oil hurts the cat and 02 sensors over time , also the valve seats start leaking so unburnt air fuel mix gets dumped on the cat and upstream 02 sensor and causes high emissions,, and only way around it is stop them from using to much oil and cheapest way is refresh them with better piston rings and new better stem seals and while doing that its worth dealing with the worn out cat and 02 sensors at same time,, i have been doing this approach for past 10 years and always have a 6 weeks waiting list as they are endless, the good thing is when done they are a pleasure to own again dont use oil and go through emissions super low,, i fit a after market cat 3rd the price of genuine ones and it does the trick,, also the mpg goes back up and over time the savings of cost of engine oil and petrol sort of pays for it self over time, also the timing chain stretches and cause part of the issues as well as running retarded timing makes the driver press throttle for longer etc and causes more heat and fuel use etc,, 02 simulator will only play with the signal and not cure the issues with the running so wont have much effect on what comes out the tail pipe,,

 

Yeah this all makes sense. Appreciate the insight. Will likely work on just exactly these things but really needed to get it passed inspection in the short term. Have a great week

 

Thanks. Just thought a one more question. With the adaptation mixture bank one. What are reasonable values there?

 

i dont use foxwell scan tool myself so chances are the reading scales would be different to what i use, i use the voltage produced by the 02 sensors as a guide to whats going on ie some clues to what is happening ie if its running rich or running lean, also knowing when system is in closed loop or not,, ie when out of closed loop it uses the heater circuit in 02 sensors to maintain a controlled voltage back to ecu ,, ie a 02 sensor creates voltage at 600c temps so if the temp drops under the heater circuit will bring it out of closed loop running and running on open loop until heats up, also engine temps have a influence on whether closed or open loop running is on of off,

 

Getting some new trouble codes. Any ideas?

 

By the way I check the voltage from the actual sensor and at idle it’s pretty constant at .7v. At 3000 RPMs it’s between .4 and .8v oscillating.

 

which about right, as for codes trouble is with cheap generic scan tools it dont see all codes prob find you have more hidden P-codes ie dealer only

 

Hey you don’t by chance have a wiring diagram for the DMTL system. I verified I had power back there at the fuel evap system but I don’t think I have ground. Not sure which wire is ground there and if it’s constant.

 

below screenshot

 

Great. Thanks for sharing this detail. So it seems like my sensor fix is working so now just need to figure out the evap system problem. Those 2 codes (2A74 and 272B) seem to show there is a wiring harness issue or pump problem. I know Im getting the 12v at the terminal 2 spot. Im having a tough time checking the actual pump at terminal 1&2. Part of my issue is figuring which one is terminal 2. The wire color should give it away but the colors for the 12v are white and red but the diagram you sent says OG and I have no idea what that means.

 

orange/ green

 

Ok. So I’m really stumped. Finally fixed my eve app system problems. But now after driving 25 miles or so I am getting this error code “ oxygen sensor after catalytic converter. Ageing”. It’s not tripping the check engine light but I’m also not getting “ready” for my emissions check. Not sure if I need to just keep driving or if it’s going to continue to not allow my O2 sensors or catalytic to be considered “ready”. Have you ever heard of this?

 

I have also noticed that after driving for a while my downstream sensor show's not ready when I'm looking at the live view. If I cycle the engine off and on the sensor will show ready again for another series of miles. Im starting to go crazy here.

 

would suspect the cat is partly blocked common is oil damaged from using oil over a long time main reason , also the 02 sensors go the same way, trying to diagnoses such faults without new cat and sensors as a base line hard thing to do, but that would be treating the outcome and not the causes ,,, ie oil burning etc timing out

 

Well crap. Ok. Thanks for all the educated insight. Lots to do here so better get started. Cheers

 

Hi again. Well I may have finally figured out what may be going on for me. In this attached schematic the yellow wire looks to be a ground wire. I’m assuming with the key on

or maybe even off this should have continuity to ground. Is that your understanding as well. If that is the case, I’m not getting any ground signal to that yellow wire from the DME side.

 

that ground is whats called a switched earth circuit that is unfused directly to cars dme ie motronic control unit they switch the earth on that circuit to prevent ecu spike issues and gives a more stable circuit for control as such ,, you will need something like pico scope to read and understand that system, below is pinout for ecu and pinouts etc,