36 replies to this topic

[Mini40UK]

I'll try and keep this epic short. Struggling with high emissions on MoT. Numerous things have been looked at/renewed including head skimmed, valves reseated and new springs, new gaskets, new lambada sensor, new cat, new exhaust gaskets, new HT leads, new spark plugs and now after research I have tested the coil and found that to be faulty....or have I?? . The figures that I am finding online is that it should be showing between 0.5 - 0.8 ohms primary (the 4 pin plug) and then the HT connectors, secondary, should be 10.5 - 13.5 ohms. Mine was reading 1.7 and then 6.9 so I bought a new one, a Lucas GLC204. I've read on here about what is and isn't a Lucas and parts from Taiwan etc. which is for another conversation but the new one that I have bought does not reach those figures. So my big question is should they?? I don't want to think I have fixed the coil problem and then get my car retested for emissions and still have problems but don't know if its still the coil or now something new to swear at. I hope that makes sense and any help would be much appreciated as I'm not getting from anywhere else. Have a good one! Richie

[68+86auto]

What are the emissions readings? The different gasses each help identify which area the fault is in.

 

an ignition fault would result in high HC (not CO). We need all four gasses to get the best idea.

[Mini40UK]

Hi, so the latest reading I had was: CO - 0.75, CO2 - 13.7, HC corr - 109, HC - 105, O2 0.77, CO corr 0.8 and a symbol thats looks like a tent - 1.010

[68+86auto]

From that reading, there doesn't seem to be anything crazily wrong and no ignition or misfire issue. An ignition issue would result in high HC.

Is that the idle test or high rpm?

What are the limits?

 

 

I suspect that might be a high rpm test due to the CO2. In that case it is likely failing on the CO as even a carb mini without cat would have a lower CO. That would mean it is running rich for some reason. Is it reaching operating temperature? (88 degrees).

Edited by 68+86auto, 07 December 2025 - 12:23 PM.

[Mini40UK]

The garage told me is was very high and yes running rich, but what I'm trying to solve is why? After dealing with the long list above my coil is faulty, or so I'm lead to believe and now I'm getting conflicting information of what it should be reading. 1 set of figures from research online and the other from the shop.....shock. As for the limits of my readings the CO should read 0.3 - 0.5 , HC should be less than 100, my tent like symbol is the Lambda which is spot on, O2 is slightly high and CO2 could be higher is the Cat was working well. All of that from online and thats the problem and why I'm here because I want some real human experience to guide me through this so I can lower my emissions, pass my ITV (MoT but in Spain) and actually just drive and enjoy it so any help would be great thanks. P.s yes I would say it reaches the right temperature, new thermostate and fan comes on.

[68+86auto]

The coil may or may not be faulty (it sounds like it is the wrong coil) but it is not the cause of your emissions failure. The O2 and CO2 readings look fine to me.

 

I am assuming this is the high speed test unless otherwise advised.

 

For some reason it is running rich (CO). This cannot be caused by an ignition fault. What temperature is the ECU reporting?

 

Have a read of https://www.crypton....emissions.html. Even that points towards a coolant temperature sensor issue.

Edited by 68+86auto, 08 December 2025 - 01:24 AM.

[Mini40UK]

Ok thanks mate, I will have a read of that link. How do I read the ECU?

[Mini40UK]

Unfortunately the link didn't work. 

[68+86auto]

Unfortunately the link didn't work. 

Try this

 

https://www.crypton..../emissions.html

Edited by 68+86auto, 08 December 2025 - 10:00 AM.

[68+86auto]

Ok thanks mate, I will have a read of that link. How do I read the ECU?

You will need the special cable and software. Alternatively for this issue the voltage at the temperature sensor can be measured.

[shera12]

I'll try and keep this epic short. Struggling with high emissions on MoT. Numerous things have been looked at/renewed including head skimmed, valves reseated and new springs, new gaskets, new lambada sensor, new cat, new exhaust gaskets, new HT leads, new spark plugs and now after research I have tested the coil and found that to be faulty....or have I?? . The figures that I am finding online is that it should be showing between 0.5 - 0.8 ohms primary (the 4 pin plug) and then the HT connectors, secondary, should be 10.5 - 13.5 ohms. Mine was reading 1.7 and then 6.9 so I bought a new one, a Lucas GLC204. I've read on here about what is and isn't a Lucas and parts from Taiwan etc. which is for another conversation but the new one that I have bought does not reach those figures. So my big question is should they?? I don't want to think I have fixed the coil problem and then get my car retested for emissions and still have problems but don't know if its still the coil or now something new to swear at. I hope that makes sense and any help would be much appreciated as I'm not getting from anywhere else. Have a good one! Richie

Sounds like you’ve done a lot of work already! With ignition coils, the resistance readings can vary a bit between brands and batches, so it’s not always exact. As long as it’s close to the expected range and the car is running smoothly with no misfires, it’s usually fine. If emissions are still high after replacing the coil, then it could be something else, but at least you’ve ruled out a big potential culprit.

[Mini40UK]

Thank you, I have now fitted the coil but unfortunately I am still getting the same type of running, strong smell of fuel, slight misfiring etc. so yesterday I did a compression test.......and that was very low. 100, 95, 110 and 110. I'm lead to believe it should be higher and after carrying out a wet test on the lowest cylinder it went from 95 to 150 so assuming that means rings, pistons, re-bore. Oh so much fun 

[genpop]

Have you already cleaned the IACV? Sometimes it is clogged and therefore does not close completely. Take it off, take care on the spring,it will fly away. Clean it and try again!

[68+86auto]

Thank you, I have now fitted the coil but unfortunately I am still getting the same type of running, strong smell of fuel, slight misfiring etc. so yesterday I did a compression test.......and that was very low. 100, 95, 110 and 110. I'm lead to believe it should be higher and after carrying out a wet test on the lowest cylinder it went from 95 to 150 so assuming that means rings, pistons, re-bore. Oh so much fun 

 

I don't believe it is your cause of emissions failure. Also I don't think you ever mentioned the symptoms before now. Don't worry too much about the compression values as long as they are even which they are.

Edited by 68+86auto, 10 December 2025 - 11:23 PM.

[NLinPEN]

Thank you, I have now fitted the coil but unfortunately I am still getting the same type of running, strong smell of fuel, slight misfiring etc. so yesterday I did a compression test.......and that was very low. 100, 95, 110 and 110. I'm lead to believe it should be higher and after carrying out a wet test on the lowest cylinder it went from 95 to 150 so assuming that means rings, pistons, re-bore. Oh so much fun 

The wet versus dry sounds like quite a different result. On what cylinders did you do a wet test? And how do the "wet results" differ from the "dry results"?