This time – a bit different entry. Hopefully, it will be interesting to you. Possibly, even funny.
Some time ago, the owner of the N43 series engine contacted me. He wanted to find out if the “inserts” of the control probes are solving the error messages regarding the CO catalytic converters for these engines. True, though, this person named these “inserts” as ”mini converters”, which allows me to assume that there is no even basic knowledge.
I sent to this person several links to the entries of this blog, which explained how the performance of the CO catalytic converters for N series engines is measured. With justification, why do such “converters” not help. But the vehicle’s owner was steadfast – several times, he sent me emails with questions about whether I had personally checked that this idea (with “mini converters”) was not working. He wanted me to test it and then give him feedback.
A moment later, this person purchased NOXEM without any additional questions. Obviously, everything was clear for him.
And then I received an email:
”So hello my friend- not really.
I don’t know where to begin, but your noxem shit is not doing its job. I replaced nox catalyc converter with resonator and after 5km steady drive faults are back (2a26, 2a27, 29f5). So why say things you have not tried or don’t know? Wtf Mr master mind? So what is the point using noxem instead of original nox sensor? Maybe finish your programing before charging people for this fault code emulator?
Feeling any responsability?”
Looks like the car has serious problems with CO catalytic converters (maybe they are even removed?) I explained that these error messages have nothing to do with the NOx system – they are related to the CO catalytic converters.
A moment later, I got next e-mail:
”Dear professor,
Actually you need to lern basics.
I fixed your shit by using this (picture below). And now I explain for you how it works.
N43b20 125kw engine has two co catalyc converters but only one probe to check efficiency of bank1, that one you know. Thing that you do not know is that second co catalyc converter efficiency is also measured, more like both banks at the same time, by nox sensor. In my case wideband sensor connected to your noxem. Ecu detects too quick mixture change and records co catalyc converter efficiency faults.
After I installed that extension before noxem sensor, mixture signal is delayed and no fault codes recorded, system is fully operational, I just done 100km all kinds of driving, stratified charge 90-95% of that range was active.
Fact is a fact, that extention fixed your shit, I do not understand how you made that emulator with “efficiency issue solving” in mind, but have not set simple mixture signal delay..”
And, to it be not just empty words, he sent the picture of his “performance”:
I believe that this e-mail is worth analyzing more closely.
In the beginning – here is a bit more detail about why/if, for these engines, the control probe “sees” only the catalytic converter/fuel mixture of the 1st bank:
I marked the location of the control probe with a red circle. Really? The probe sees only one/first bank?
Let’s take a look at the next stage of the exhaust system:
In this image, I marked with red the stage, which is connected to the “outlets” of the catalytic converter from the previous image. As you can clearly see, both outlets are connected!
The conclusion is one – the control probe sees BOTH banks! Yes, technically this is not the best solution, but – it works.
Why does such a solution work? The reasons are simple:
a. in idle and low requested torque (when the efficiency of the CO catalytic converters is measured and the wideband probes are trimmed), the speed of the gas movement in the exhaust is relatively low. The exhaust gases are excellently “mixing” in this Y connection.
b. the exhaust gases are not evenly “moving” via exhaust pipes in the direction of the exit, but the movements are pulsing/vibrating. These pulsations of the gas movement (changes in the pressure) pulsations make the previously mentioned mixing of the gases more efficient.
Note: this link is a good example of how the control probe “sees” the air suction, which is AFTER it (further to the direction of the exhaust), very well.
Regarding the part of the e-mail in which the person makes a statement that the NOx sensor is used for the CO catalytic converter performance tests – I will have to disappoint all the supporters of such an idea:
a. the OEM NOx sensor is located too far in the exhaust system – even if this sensor is in perfect condition, it can’t be able to detect if there is/is not even a minimal performance of the CO catalytic converter, the exhaust gases are well “mixed” in the long pipe and the labyrinth of the NOx catalytic converter;
b. a measurement of the overall performance of the catalytic converter is not possible because the NOx catalytic converter is very “spacious” – it introduces difficult-to-calculate tome delay, which is very dependent on the performance of this catalytic converter too.
No, the NOx sensor is NOT used to measure the performance of the CO catalytic converters!
But how about the person’s claim that he has driven 100km and everything is perfect?
There are several explanations:
a. when the full functionality of the engine is restored (actually, thanks to NOXEM in this case), DME resumes the creation of the injector and bank adaptation. According to my experience, at least 80% of the error messages regarding CO catalytic converters are recorded not because they have completely lost their efficiency but due to overload (the incorrect fuel mixture comes from the engine and/or there are misfires). When the DME makes the injector and bank adaptations correct, the density of the misfires reduces too, and the catalytic converters are “recovering”;
b. when the NOXEM was installed, DME restored the Stratified charge. The Stratified charge is the most comfortable fuel mixture (and the thermal mode) for these catalytic converters; it has a positive impact on their performance;
c. if the customer finally has decided to perform the re-adaptation of the engine (it is clear that he did not perform it previously because 0 who follows the RFML), DME forcibly creates a new adaptation and gives a certain handicap for recording the error messages of the CO catalytic converters. This handicap is made exactly for such situations – to avoid UNJUSTIFIED error messages after repair, during the creation of the initial adaptations.
The true performance of the CO catalytic converters will show only after longer tests (it takes several hundreds of km to measure the CO catalytic converter and certain driving conditions). If the error messages regarding CO catalytic converters appear later, the injector adaptations and the misfire density should be evaluated. Only after all adaptations are correct, the correct fuel mixture is confirmed by the mechanical efficiency of cylinders, and the misfire density is 0 will the actual picture regarding the performance of the CO catalytic converters be seen.
True, though, this person, most probably, is not interested in anything of this. I assume that a new urban legend has been born – the positive impact of the NOx sensor spacer on the error messages of the CO catalytic converters.
