Severe emissions failure - NOx doubled

[Junior]

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Is the vehicle running any hotter? Maybe the coolant is running too hot?

nope, in fact, after doing a changeout and multiple flushes to G-05 coolant, the car runs slightly cooler, about a needle width below where it usually was...



I wouldn't have a high level of confidence with the factory idiot gage. Temperature sending units can and do go bad. I had one that seemed to work but would never go above 180F even on a hot day when I forgot to remove my winter front.

 

[tc2468]

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your chip killed the cat


Except that it barely passed NOx when the OE chip was in there... With the chip in there it was consistent with the OE cat in the car. In an attempt for a quic fix last inspection, 2 years ago, I swapped in a new 3-way converter, which made me barely pass.

Only this time is the Nox reading crazy high... and OE chip doesnt make it go back down, in fact it has gone up!



hey JMH, typically, aftermarket chips will advance your ignition timing and increase fueling maps. I am speculating that over time the overly rich mixtures overheated your cat and is now ineffective (with or without your chip).

how are the plugs and wires? any misfiring? any black soot on tail pipe?

I wonder what your readings would be if you had a new cat and no chip installed. The OEM cat was prob. much better at cleaning the exhaust (more platinum,palladium etc.. than an aftermarket unit therefore lasting a lot longer.

any coolant related issues? possible contamination of the cat (coolant in the exhaust) would also result in poor cat performance.

I have programmed chips before (ecu's similar to your bmw motronic and k,l jetronic) and have had similar pre-mature cat failures due to chipping.

good luck

 

[HondaMan]

I'll second that the chip killed the CAT.

Also for those mentioning timming, it cannot be set. Nothing can be set, air fuel, idle speed, all are computer controlled.

I did not notice a mention of mods to the air intake? If done, I would put back the OE air intake until testing is completed.

 

[trixman]

There may be carbon built in the upper cylinder area and the exhaust including of course the Cat. May want to use your preferred method of cleaning. I'd do that before an expensive cat change.

The amsoil foam product through a vaccuum line comes to mind.

 

[JHZR2]

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hey JMH, typically, aftermarket chips will advance your ignition timing and increase fueling maps. I am speculating that over time the overly rich mixtures overheated your cat and is now ineffective (with or without your chip).

how are the plugs and wires? any misfiring? any black soot on tail pipe?

I wonder what your readings would be if you had a new cat and no chip installed. The OEM cat was prob. much better at cleaning the exhaust (more platinum,palladium etc.. than an aftermarket unit therefore lasting a lot longer.

any coolant related issues? possible contamination of the cat (coolant in the exhaust) would also result in poor cat performance.

I have programmed chips before (ecu's similar to your bmw motronic and k,l jetronic) and have had similar pre-mature cat failures due to chipping.

good luck


Interesting... mine is a Dinan chip, whose equipment is CARB and emissions/new car warranty certified by BMW.

This all makes sense, except that when I cut out the old OE cat, it looked great, and I had the identical NOx problem before and after the chip.

Im going to be replacing the cat converter with OE, so perhaps Ill leave the OE chip inhtere too...

Thanks!