cmsgama

Hi

I do my search here on forum and I need more ideias.
I have a rx7 13bt s5 streetport, stock ecu, without all emissions devices, full exhaust system from racingbeat without cat. I faill my emissions test this year, because my man inside can't help me this year.

Here in Portugal the test is simple, the car only stay idle. I only have to pass on CO, and my limit is 3.5% and I get 4.1%. what you think about this? If I put a cat, is possible reach the value that I need?

The CO value is high when I have rich AFR?

Help on this

regards

Brodie121

iTrader: (8)

Make sure you get the car warmed up really good before the test and new air filter would also help, a cat should be a able to get you to pass iirc, let someone else confirm this before going out and getting one tho.

good luck

cmsgama

Ok, Thanks

I hope this result.

regards

cmsgama

Ok, Thanks

I hope this result.

regards

j9fd3s

iTrader: (3)

all you have to do is 3.5% CO? i'd LOVE that test, should be very easy, you can either lean it out, put a cat on it, use alcohol as a fuel, put the air pump back in...

just about anything should work, a STOCK car will run something like .04-.08 CO

cmsgama

I will put only a cat, warmup, and try the luck. I hope the cat remove more than 0.6%CO, to pass. I get 4.1% in the last try, without any emissions devides. Now with a cat I hope have better luck.

What you think by your experience?

regards

ericgrau

iTrader: (1)

Besides the cat you also need a way to lean it out. Air pump, lean tune, alcohol or etc. will all do it. If you still have your O2 sensor it should automatically make it go lean at idle regardless of tune. The cat only accelerates the reaction between oxygen and CO. No oxygen means no dice.

cmsgama

My O2 sensor is new, and I have the stock ecu, I hope that it give me a lean AFR at idle. Without any emissions devices including cat, I get CO 4.1%. If I advance a litle the timing, did I have a big change on CO value?

regards

ericgrau

iTrader: (1)

It will probably have a small effect, but in the engine lab I did at school timing mostly only affected NOx. Retarding timing reduced NOx. I think the reason is that advancing timing moves more of the burning into the engine where NOx is formed while retarding it moves some of the burning into the cat where the CO gets consumed anyway (and NOx is not formed). But you didn't have a cat. So w/o a cat advancing may help more.

Yeah, with an O2 sensor hopefully the stock ECU will run at stoich (not rich) and it'll burn clean. Otherwise stock runs rich and you'd really need the air pump. Alcohol could also lean it out, but if you do it wrong on a turbo and hit the boost you could cause detonation and then bye bye engine. Also note that the cat will get destroyed after a long period of time (weeks? months?) if you leave it on without an air pump.

Ideally you'd have a high flow cat with a good reputation in rotaries (i.e., doesn't melt even though rotary exhausts are hotter) plus an air pump year round so then your air will be cleaner and you won't have to worry next year.

j9fd3s

iTrader: (3)

timing has no effect on CO, it does raise NOX, ive done a couple back to back smogs

http://www.mgexperience.net/article/co-afr.html

just putting the air pump on should work...

http://www.fuelsaving.info/lambda_emissions.gif

the only real unique thing about the rotary, is that if you run it lean (near idle) it will misfire, which results in high emissions, so the factory runs it rich, and then adds air via the air pump, to compensate.

as you can see from the chart, going from 4.1 to 3.5 isnt a huge step... especially when you consider that a stock car will be under 1% (idle afr's are 16-18:1 which is literally off the chart)