Ulysses

I know what most those words mean but I really don't have a clue what you are on about! As long as you do and can get a clear ticket that what matters!

wrote:

The factory ecu is gone and replaced with a DTAfast S80 ecu to run the individual bike throttle body setup on the M18vvt engine. Most of the sensors are there apart from anything in the exhaust now, so the ecu doesnt do any fuel trimming based on lambda.
 

Ah, I forgot you are using ITBs. I run my trials car on a Megasquirt which also does not use any lambda sensors. Luckily in my case the car is old enough to only need a visible smoke test. I tend to run on the rich side to try to control pre ignition.

Running rich can overheat cats, which may explain why yours doesn't work very well now.

Lambert, here's a bit of an explanation about what is going on.
Modern cars have sensors in the exhaust (lambda sensors) to measure how well the fuel is burning. They can tell if too much or too little fuel is being used for the best emissions and economy. Riccy is using a custom fuel injection system that does not use these sensors. The system was calibrated on a rolling road when it was first installed. This method is not as accurate but can give more power at the expense of fuel economy and emissions.
When you start a cold engine the fuel does not vapourise very well so the fuel injection adds more fuel to compensate. It's the equivalent of the choke on an old carburettor. When Riccy's injection system was set up the sensor that measures engine temperature was set up wrong. He later changed the calibration of this sensor which means the system now continually thinks the engine is cold and dumps in too much fuel, killing the emissions. As it is not using a lambda sensor it does not know it is running too rich.

Hopefully setting the temperature sensor back to it's old calibration and maybe replacing the cat should solve the problem.

 

Ah Stoichiometry. I've heard of that.

Thanks Les, That is a masterful summary of what I think is happening. Essentially the mapping was set when the coolant sensor scaling was wrong, so the map temperature was calibrated based on the wrong measurement. I changed the sensor scaling without altering the map, resulting in the ecu thinking is -10 most of the time and going into cold start mode unless I get it really hot. This may also explain the 140ish miles-to-a-tank comedy fuel consumption I get.

Lambert, you are showing off, but Stoichiometry (yes i had to look it up...)  is working, but not as efficiently as it should currently, therefore the emissions are worse than a 40yr old tractor 

Yay! a pass  

Set the sensor scaling back and there was an immediate improvement with the idle at running temperature as well so hopefully that was all

 

All good for another year then.