I was disapointed to see the check engine light come back on yesterday morning. So that afternoon I stopped by a buddies shop and borrowed a cheap scanner. It came up with 6 codes, p-0135, p-0136, p-0155. It showed these 3 twice. According to this forum, that is both bank 1 and 2 upstream heated O2 sensor circuit fault, and bank 1 downstream heated O2 sensor circuit fault. Now i fully understand that its my offroad h-pipe and the MIL eliminators causeing this, but what dosen;t make sense, is, why are the upstream O2 sensors being effected? Shouldn't it only be the downstream (aftercat)? And why is only one downstream haveing a fault? The check engine light has come bakc on today, after i had cleared codes yesterday, and I assume it will be the same codes. Is there anything I can try besides spending 400 dollars i don;t have on a catted pipe, or 375 i don;t have on a sct tuner? I have the stock pipe i can put back on I guess, but i was just getting used to the loud sound and the extra power. Also as long as the check engien light is on, and the ECU is ignoreing the O2's the car runs WAY too rich, i feel less power, it is noisier in a dirty old truck kind of way, and when I'm sitting at a light witht eh windows open all i can smell is gas. Sorry for the long post, and thanks for any help.

 

disable the rear O2's (usually done with a chip), buy some cats and weld them on to your offroad pipe.

Clean the O2's or buy 4 new ones (about 400 bucks worth) since you've almost certainly fouled the ones you have possibly beyond the potential for re-use. As long as it's running rich you'll keep fouling the o2's. Your car needs the O2's to work properly so it can manage the fuel delivery.

Simple route, stock H pipe, new O2's.

Hate to be the bearer of expensive news. Or, swap your offroad pipes for a catted H or X pipe.

 

Or try new MIL's? Don't know if you have the cheap ones from ebay, but you could try steeda's.

 

I thought about suggesting that but I've only ever seen MIL's extend the time between CEL's and not solve the problem. never really mattered to me though... california has smog ****'s everywhere so cat's are the only way to go... else you get a 1000 dollar ticket.

 

i dont know if this will work but a grease monkey told me this. get some spark plug non-fowlers 14mm and put them into the O2 bungs(down stream) and make them about 4 inches away from the pipe. you may need 2 per side if they are short ones, he told me this gets them out of the direct stream of exhaust. they guy said he does this to cars that "require cats" but whats to take them off. and he said he doesnt use MIL's or anything like that. now he could be lying or he could be dead on. but what the hell, $10 vs $400.......you make the call...ive havent tried this but you can bet yor *** im gonna when i get and o/r h pipe...

 

Thanks for the replies so far, I am currently running the Steeda brand MIL eliminators. They worked great for about a week, I installed the H-pipe the saturday before last, took about 2 days for the check engine light to go off on its own, never had time to check or clear codes until the light came back on a week later(yesterday).

 

The really rich fuel mixture is what caused the o2's to go out in the first place. Unburned fuel kills them. Before you know it, under acceleration, your car will let out some nice black smoke from all of this.

When I get my h/x pipe, im getting catted, for this very same reason. Of course, you can tune it, and fix this problem.

Look to sh*t out another 300-400 paso's.

 

well....that last post was a bummer. But thank you regardless. I glad i finally got a second car last weekend, (the reason i don;t have 400 dollars), and i can stop putting miles on the cobra for a while. I think i will probably put the stock pipes back on till i can afford a catted one. Part of why i went with no cats was to have an inexpensive pipe untill i could afford longtubes with a short catted pipe. I guess i can get the SLP h-pipe that can supposidly be easily changed to fit longtube headers. Although I haven;t seen any SLP long tubes for my car, I assume BBK longtubes would fit the SLP pipe. grrr. So much money. Sorry, just a lil cheap right now couse i just dropped 2 grand on a very high milage jeep cherokkee, just to have to buy a new header for it cause the old one had a weld pop. o well, guess i need to keep ont eh look out for that new job. Sorry for the slight rant, thanks for the info.

 

why in the hell would he turn off the rear 02's, then weld in cats. Thats just stupid...

 

not really... Bassani catted X pipes (as a for instance, others do it too) have cats but have been known to trigger rear O2 efficiency CEL's. So you can turn off the rear O2's and then it's not a problem there smart guy. Don't call it stupid if you don't know the reasoning.

BURN.T

7 posts and he's already off to a poor start. Smooth.

 

i ran a o/r h on my car for about a year and a half before i switched to my catted one... u think i could have fouled up my o2's as well?

Ive noticed it is running a lil rich but it could just be my imagination. and it still throws codes every once in awhile, even with the catted pipe

 

it's easier to just pull an O2 and see how it looks than to have me speculate. If there's a bunch of soot built up on them, then they won't work at peak efficiency and will return skewed data to the ECU.

If the light only trips once in a while, that's pretty normal with the Bassani catted x. Nonetheless, get a dyno run with wideband A/F done and then you'll know for sure. If it's running rich, you'll need to sort out the cause which could easily be fouled O2's or just a simple minor exhaust leak.

 

Well, my car is a strange moody beast. On the way home just now the MIL light turned off. Within a couple minutes of that happening, the car stopped running so rich, exsaust noted cleaned up some, and got noticable boost in torque. I think my car just runs kind of rich anyway, so the MIL eliminators must be doing there best, but the last coupel of humid days must have made it run rich enough to trigger the MIL. I remember a couple monthes ago with the stock h-pipe in Fuels 2 class i had a fancy expensive Ford scanner on my car looking at pid data. I watched my O2's while we messed with stuff, like caused lil vacume leaks and such. When the car was warm and idleing the O2's were constantly putting out about .6-.85 V, which if memory serves is on the rich side. Maybe the scanner just wasn't refreshing the screen often enough to see it flip below .5V, or maybe it just runs rich. I can't remember if we checked my car's long term fuel trim, I think we only watched short term, but maybe we did. That might help explain why the mileage sucked when it was stock, and gets noticibly better with every mod.....even rear gears. I don't know, I am curious as to how it will react when i eventually get a SCT tune on it. Well, thanks for the help, I think if it comes back on and stays on for more than a coupel days I'll put the stock pipe back on till I can at least afford a tuner. Thanks again.