RichardZ SS

I deleted the cats today, hooked up 02 sims to the rear 02 sensors, and put a Loudmouth exhaust system on. A few miles later and Im now throwing a SES code po400. After doing a search, I see that the code is due to no back pressure on the exhaust system. I also found this thread http://web.camaross.com/forums/showt...+monitor+ready explaining it all, including my options on how to get rid of the SES light. My question is, am I losing anything performance wise by just ignoring the light and driving it? We dont have emissions testing here so thats not a concern. This LM1 exh. system is EXTREMELY loud and in the near future I expect to be replacing the resonator with some type of actual muffler. Do yall think that by doing that I will gain enough backpressure to once again not set the SES code?
OOPS! Guess I should have told yall what car this is too huh!? LOL '96 Formula w/lt1 of course!

RichardZ SS

TTT come on folks, help me out here! Im kinda **** retentive ESPECIALLY when it comes to my cars and SES lights!

frankthetank078

i have the same problem with my exhaust...since the cats gutted i get my SES light on after 2 minutes of driving...the way to get it off would be a tune and tell them u dont have a CAT so they enter the right amount of back pressure into the tune but i think u gain like 5 hp from a gutted cat not positive.But it isnt something you should worry about

93turbo5oh

the code is gonna stay as long as you dont have 02 simulators. back pressure has nothing to do with it. its a 96, so it has the 02 sensors behind the cat, thats whats setting off the code.

as far as the 93 goes, the code isnt from the lack of a cat unless someone put an obd2 pcm in the car.

RichardZ SS

I had it scanned so Im CERTAIN the code is "po400 egr malfunction flow restricted".
On a positive note, while waiting on a reply, I went out and did the TBbypass mod just for giggles.

Injuneer

No. P0400 sets when the PCM cycles the EGR valve, and doesn't see the change it expects in the intake manifold pressure (MAP). The diagnostic is intended to detect low flow through the EGR. Backpressure has EVERYTHING to do with it. It has absolutley NOTHING to do with the post-cat O2 sensors or sims. And, he already has sims.

You tune out the diagnostic (may leave you with a "system" not ready flag), or you put in a spoof circuit that inserts a resistor in the MAP sensor signal wire when the EGR solenoid is supposed to be energized.

RichardZ SS

Come on man! Tell me what ya think about this part of my original post:
"
My question is, am I losing anything performance wise by just ignoring the light and driving it? We dont have emissions testing here so thats not a concern. This LM1 exh. system is EXTREMELY loud and in the near future I expect to be replacing the resonator with some type of actual muffler. Do yall think that by doing that I will gain enough backpressure to once again not set the SES code? "

Injuneer

You aren't losing performance. But if something serious fails and would have turned on the SES light, you'll never know it because the light is already on.

93turbo5oh

i didnt see that he had sims. i just turned all that emissions **** off on my car. so i dont know any of those codes. all i saw was taking off the cats and codes. sorry for the bad info. it seems odd to me that it would set an EGR/MAP code. but then again, all the 96-97 cars ive worked on we converted to OBD1 and took/turned all the emissions stuff off. im not going to pretend i know how all that stuff works, i honestly dont care. i throw emissions equipment in the trash.

crb806

sorry to jump off subject but how does your car sound with no cats and LM?

RichardZ SS

TOO FRIGGIN LOUD! Not a good loud either, but more like that "old rusted out truck with no pipes at all" sound. I can however tell a HUGE difference in power now as compared to the bone stock system it had. I wanna keep the power but lose the NASTY sound! LOL