12 replies to this topic

[AeroNotix]

Hi, 1998 MPI. 

 

Today I had my annual inspection and it turned out that in my emissions I had 2.5% CO (instead of the allowed 0.5%). Only thing I could easily replace for this would be the lambda sensor but as they're bloody expensive I wanted to get a reading on it.

 

I found a place locally that had a Sykes Pickavant. The lambda sensor voltage is pegged between 1.99 and 2.00 so definitely will be replacing it.

 

However, I also had a fault code which kept reappearing. The intake air temperature sensor was being labelled as faulty. The value was appearing correct from the live data.

 

The sensor itself isn't particularly held in well, I can pull it out without needing to unclip it so potentially it's just loose.

 

Also, if say, the IAT sensor is completely shot how would that manifest when driving the car? I assume it may over/under fuel and affect mileage and/or emissions?

Edited by AeroNotix, 14 September 2017 - 06:15 PM.

[FlyingScot]

Inlet air has a minimal effect on fuelling compared to coolant temp for example.
Was it a live fault on the ACR ? There are stored and live faults
If it's reading low it will over fuel but slightly only. Or could be a wiring issue which is worth checking first.
If it's shot it substitutes a temp value (can't tember off the top of my head)

FS

[AeroNotix]

We cleared the fault several times but it would immediately come back. I don't recall any wording with live/stored faults but it was the first time I've used this reader (and first time reading a mini) so I am not familiar with exactly how it works.

 

To be clear: the fault came back after clearing all error codes.

[FlyingScot]

Okay depends on software version and whether ACR, ACR2 or ACR4, but sounds like a live fault.

Check wiring first and clean sensor with brake cleaner, it means the reading received by MEMS ECU is outside the range expected

FS

[AeroNotix]

The value was shown on the reader and it seemed to display a range of acceptable values, I believe it was 50-100 or something and the value was 95. Not sure if that's celcius but the ambient air temperature was around 25c so I hope not!

 

I don't particularly want to check again as this dude charged me 50zl for the pleasure of borrowing his reader for 10 minutes!

[FlyingScot]

It's in Degrees C on an SP unit.

FS

[AeroNotix]

RIght I've replaced the lambda sensor and it starts up and doesn't act strangely so I've not broken anything. Not had time to take it out and about to properly test it and allow the lambda to warm up.

 

That said, the car is clearly running rich. The spark plugs are sooty/black and so is the exhaust. It's still doing that but as I said, lambda isn't warm.

 

What else can cause a rich running A series? All air intakes look good, new filters, no blockages, etc. Should put another reader on it with the new sensor.

[FlyingScot]

Without diagnostic equipment or following each fault to the end you will go around in circles.
Check the lambda is working since you've bothered to replace it.
Check the IACV is working as there is no feedback loop on this so even if MEMS thinks it driving it it may not be.
Clean it with carb cleaner

FS

[jamesquintin]

have you replaced the temp sender and done the wiring upgrade..?

​If the ECU thinks the car is cold,, it would overfule it?

​Q
 

[AeroNotix]

Good shout on the IACV. One of the first repairs I did on my mini was to replace the housing. When stopped and in neutral, giving it a lot of revs (manually opening the throttle) I can hear as the revs die down a little sound as if the throttle is opening. Though I will check it further.

 

James, I've not looked at the temp sender. I didn't get a fault code for that and when driving the temperature gauge actually moves (for whatever that's worth).

Clean what with carb cleaner? The IACV? I did that when replacing the housing a while back. The car has been running rich since I bought it (carbon deposits on the spark plugs and in the exhaust is where I'm getting that idea from). 

 

I'll try to find someone else locally with a reader. The guy I went to before is miles away.

Edited by AeroNotix, 22 September 2017 - 08:49 PM.

[genpop]

Hi Aeronotix,

i'm not familiar with MPI, i own a SPI but I know lambdasensors do not work if the heater coil inside the sensor gets no current so check the main relais with following wiring and plugs to the sensor.Or connect  your old sensor , turn on ignition and have a look if it gets warm.

[AeroNotix]

I've decided to just throw in the towel and buy a Sykes Pickavant ACR4. My mini is currently undergoing a bit of surgery due to me spilling a lot of DOT4 around the clutch master cylinder and letting it soak! (I'm not a bright man) Once that's taken care of I hope the reader will be here and I can quickly verify the new one is working. If not, I'll start poking around with the MM.

[AeroNotix]

OK So I have a reader and just went to test it's working. The mini's injection system has been in bits and unplugged for about a week while I urgently fixed the spilled DOT4 which ate through paint and started rusting the bulkhead. The battery has also been unplugged all that time. I've got it all plugged back in and ready to drive. Still need to just bleed the clutch but will get to that shortly.

 

I've got to just test my ACR4 reader to see what values I get. I am looking at the TPS reading (labelled as THROTTLE POS.) in the reader itself and without touching the accelerator, it reads 5, when I depress fully it goes to 74. Is this correct? It's not entirely related to my issue but interested if the scale should be 0-100?

 

Even if I turn the throttle on the inlet manifold itself it still reads 5-74. Despite this, the THROTTLE SW. reading immediately goes from OFF to ON when I move the throttle manually even a tiny bit. So I would assume the ECU has "learned" that the reading of 5 is "off" and anything higher is ON? Not sure if the ECU will learn from his value and adjust accordingly.

 

Hoping it should be 0-100, maybe I can get it running a bit better at W.O.T! 

 

Put my question another way: is there a listing of what the acceptable ranges for all values in the live data section should be?

Edited by AeroNotix, 05 October 2017 - 02:41 PM.