I am using the Comptech SC with emanage, RC 440 cc injectors and 8lb boost pulley. I tunned my car with additional fuel map, A/F, and VTEC engagement. I just installed the injetors few days ago, and then, i used the A/F meter to tune my car to keep the car running at 11.5~12 A/F. however, after some runs (40-60 minutes after the car was done tunning), it throws the CEL. I am running the stock cat and stock exhaust, my friend believes the CEL was from the O2, and he believes that if i get the straight pipe with 02 simulator, it will be gone. However, I don't wanna put my bet on him once for all. therefore, I am asking if anyone knows what might cause this. in the mean time, I will go get the code to see what really throws the CEL. please do share the info. thanks.

 

The only way to know for sure is to pull the code. Without it, you are just guessing.

 

does anyone has the similar situation?

 

I wouldnt want to guess at it. Pull the code to make sure, it could be anything.

 

You MUST have a code before guessing at what it could be.

 

P0172 is the code which it says primary O2 sensor runs too rich..
it might be the A/F ratio was tunned too high for close loop... what do you guys think?


In addition, should I run the boost limitter cut setting and take off the EMS?

 

The boost cut function is the same as a MAP clamp, or the Comptech ESM. It is very different from the AEM EMS.

There is no reason to use the MAP clamp, when the E-manage has the same function.

It sounds like a re-tune is in order to fix the CEL.

 

You could be running too rich or your O2 sensor may have been damaged or your EVAP cannister purge may be faulty.

 

Now, I need to find out the problem with my car....

I went to do the dyno tune, the tunner told me he keeps 13.7~13.9 A/F for my close loop range(light loop for mid to low rpm), and 11~10.8 for my open loop range (under hard accelaration). My CEL comes up again now. it is the same, O2 sensor 1 too rich. Now, what is the A/F I suppose to set for close loop?? will 13.7~13.9 be enough? If not, what will be the best? or it might very well be the demaged O2? if it is, how to find it if it is demaged?

second, I am now setting 2.90 for my boost limitter cut voltage, however, sometimes it works and sometimes it gives me problems. The timing of nagative pressure turn to positive pressure, the car seems not accelaration for 1 second or 2, the accelaration comes back again.i have changed it to 2.75 without future fuel tunning now, the problem seems doing better. but the problemit "might" still be there . what should i do with it? the ESM is taken off.

 

by the way, the fuel in Taiwan is really terrible, my tunner was trying to set 11.5 AF for 8000 rpm and it actually knock, so, he made the change to 10.8 in the end, luckily, i got 291 rwhp now he believes that if I could run 12.5 A/F with the fuel in states or even from Japan, my car could break 300 rwhp easily (stock cat converter and exhaust)