Well like the title says, I have a 2G talon (95 to be exact so i cant do an OBD2 scan I have to do a sniff check) and I am failing emissions because the car is letting out too many hydrocarbons. The limit here in Nevada is 220PPM and my car failed at 230PPM. I have done all the standard maintenance like new plugs and wires, fixed vacuum leaks which actually made it worse. I know the question has been asked before but most of the answers were to put the cat back in the car, I have a cat and it is relatively new Is there any thing I can do with the tune to lower the HC's? lean out the idle or advance ignition perhaps?

Thanks
Mike

 

Hydrocarbons are from unburnt fuel or fuel evaporation. Im not sure what your a/f's are at idle, but I would think that if you leaned the a/f's out slightly in the range of cells that the sniffer test is performed, your hydrocarbons should drop. But, remember leaning out the a/f's will increase combustion temperature, which in turn will increase the production of oxides of nitrogen (NOx). Which is also tested during the sniffer test by emissions facilities.

Lower combustion temperature = higher production of hydrocarbons and lower production of NOx.

Higher combustion temperature = lower production of hydrocarbons and higher production of NOx.

Hope this was of help.

 

Right now the ECU is running at around 14.7 as it should. The trims are subtracting some fuel however they aren't maxed out so that shouldn't be an issue. As long as the ECU continues to keep the AFR bouncing around the 14.7 range then it should pass, or so I thought. I tried locking the ECU in open loop and I leaned out the the low load/low rpm area of all of the table however that didn't have an effect on the wide band any, the AFR didn't change at all so I am not sure what is up with that. I did come to the realization this evening that when I had this ECU connected to the engine with the 96 CAS I had changed the wiring around a bit for the injectors and ignition in order to compensate for the inverted CAS signal and I may not have switched them back. Even though the car runs sound after changing to the 99 CAS which is more similar to the EVO CAS I will have to get under the dash and check that tomorrow and see what I find... I will continue to mess with things to see what I can come up with.

Thanks so far.

 

put it in open loop n lean it out a bit. im sooo happy i have people in ny that look the other way and i just slide em a few extra bucks.

 

I wish that were the case here sometimes unfortunately the only way to cheat the system would be to shove the sniffer into the tailpipe of another vehicle. Once you start doing the test whether you pass or fail the the guys at the test kiosks have no control over the machine sending the results to the DMV.... I will try leaning it out a bit when I take it back over the the test place.

 

It helped me a lot of times to satisfy sniffer test by changing the oil, I cannot recollect how much was the difference with HC after changing the oil, but there was a significant difference with new oil. The unburned particles dilute within the oil and then they contribute to exhaust gases. I hope it helps you as well.

 

just put in a gallon of methanol or ethanol and fill up and then test again. should solve the problem...

ps. running leaner at idle doesnt increase temps, it decreases them (how do i know, im a powerplant engineer)

 

I'm not trying to bring this thread back from the dead.....but, I just noticed that there were responses. I must tell you that I literally laughed out loud at your "running leaner doesn't increase temperatures, it decreases them" response. Made for a good laugh.

 

Run a car real lean and see the Exhaust manifold Glow cherry Red, ive ran a SBC pretty lean when adjusting timing for a new cam i installed,and dam i thought the headers were gunna melt.