Hi James,Just to revisit this, I put oem cats back on for the mot, and have left them on as an experiment. No cel yet, and I definitely would have by now with the sports cats, but having suffered cat failure once in my life, I am now bricking it that it may happen again.
No, I'm still running stock system, and no cell. I did investigate having a custom system made a few weeks ago and talked to the fabricator about cel problems with sports cats, he suggested using lambda cheaters as a possible solution. I always thought they were just extension tubes for the lambda, but he said they actually have 'mini cats' in them to fool the system, may be worth a try for not much expense. From memory I used to get ' P4021, and P 4031' codes from memory.Hi James,
did you ever solve the cel problem as I am having the same problems with the larini cats.
if I’m dawdling it’s not hot enough Cel then on motorways I get slow down over temperature.
regards
H
Just looked at the recorded data as suggested, on the O2 sensor voltage one looks distinctly different to the other. Would that indicate a failing lambda bank 1?Is P0431 the only code you are getting? That is for bank 2. I suggest that if it was an overall issue you’d also be getting P0421, which would be bank 1.
I assume you have checked for leaks etc?
You can check the cycle time of the lambdas, which gives an indication of condition, as I said above.
Reading the code description for the thermocouples, it reads as a sensor range/performance issue, not a high or low temp.
View attachment 119019
While there are few guarantees, it seems likely that you have at least one faulty lambda and you need to look at the sensors to see how they are fitted and wired.
The higher flow cats will change how the sensors read and operate, so it’s not a surprise that if they were heading toward the end of their life that they could then be tipped over the edge.
The difference is in the length of the cables for one, the front ones won't fit on the back because the cables are not long enough. Bosch Lambdas are fine think the oem are actually Bosch, I fitted 4 new Bosch ones to mine and even the writing looked the same as on the ones that came out.Final thought, on the standard version there are 2 cats and 2 lambdas one before the first cat (182837)and one after (191412)which are different part numbers. What’s the difference?
on the larinis there is only one cat at the rear with one lambda at the front end, which lambda should be used front or rear and could this be causing the problem. I think I’ll invest in two new lambdas anyway but there is a wide variation on prices from £50 Bosch to £200 Maserati, can anyone recommend any alternatives.