I have a check engine light from running with a race-only exhaust that has no cat. I realize that the light is on because the 2nd O2 sensor knows there is no cat, but could that decrease performance? Would a CEL from the 2nd O2 put the ECU in some sort of limp mode? Just asking because I ran some times this weekend that were way off compared to other guys that have the same mods and same tuning as I do... never thought to ask if they had O2 stimulators....

Thanks!

 

NO WAY! Ran a 12.4 at 112mph with it on.

 

A guy I know told me there is a mode the ECU goes into if you get the light. Car runs very rich (limp mode) he got the o2 simulator and he could feel the gain of power back. Weird I know. I currently have a service engine soon light on and i'm going tonight to have the code read. I have a full 3" exhaust with high flow cat, so i''m curious to see if it is cat related or if i'm getting the p0300 code thing people have been talking about.

 

cayman...don't go to Sheehy Manassas...they wouldn't even tell me the code, much less friggin clear it...all because my exhaust is 'modified'...AARRGGHH!

 

Camdog.... that is very very poor customer service you got. The more time goes by the more I hate mitsubishi. I am going to advanced auto parts in herndon and i'm going to borrow their obd ii scanner. I used it friday, but showed no codes. I learned that when you pull the battery cable to clear the CEL it also erases any codes that were in the ECU. Well I have driven over 300 mile since my last CEL and it finally came on, so i'm going to investigate. I sure hope it isn't the PO300 code. That will be a pain in the *** getting the factory ecu flash and then having to send the ecu back to WORKS to have flashed again.

 

Well I just got back and read my codes and it turns out to be a PO420 (Innefficient cat code) Guess even with a high flow cat we can still get this code. I'm going to call Buschur today and let him know and hopefully get a o2 simulator to fix the issue. By the way advanced auto parts in herndon are great. They let me use the (ACTRON CP9135 obd II card reader free of charge) all the other places around here want to charge 40 bucks to read the damn codes and reset the light!

 

That's probably the exact code I got...they said it was a converter code...hmmm. Let me know what buschur says...I'm interested in hearing what they say...Where's advanced? Is that the one beside the clock tower?

 

I have read more then one thread where this was asked and everytime the answer has been: " A p0420 inefficient catalyst does not cause the ECU to change its perameters".

 

** UPDATE **
Yup advanced auto is right next to the clock tower. Great bunch of guys there.

Buschur Racing has already sent me free of charge an O2 simulator! I can't compliment them enough on their top notch customer service

GUACK007 you are correct... the PO420 code does not change the ECU parameters, but disconnecting the battery to get rid of the code will cause the ECU to be out of wack as it takes about 200 miles to adjust itself once again so you will feel a power loss for the 1st 200 or so miles.

 

Holy cow... I'm going to call Buschur. Thanks Cayman for doing the legwork!

 

Glad i could help Steve Are you also getting a CEL?

 

On my setup the p0420 code comes on on the second key cycle after I reset the ECU everytime and stays on for good. I have a catco HF cat.

 

Cool Cayman.

I was wondering the exact same question, and wasnt sure if my code is the cat or the dreaded misfire. I'm almost certain it's the cat, and I was starting to get paranoid it was affecting perf.

I'll go confirm the code and go from there. I've heard that Autozone will check codes for free. I did just pull the fuses to reset the light, so I guess I need to see if the light comes back first, heh.

Take care,

FB

 

Did you try the spark plug anti foul adapter trick to pull the rear O2 farther out of the pipe ??
Made my P0420 go away with the UR cat. Not been back for almost 10K+ mis.

 

mikesevo8:

mind elaborating a bit more on that spark plug anti foul adapter trick. I'm interested in know how to do that. Maybe I could even give it a try before putting the O2 simulator on.