Hey Guys - This is likely to be a long read, but I'm looking for some help

First of all, Prior to this I had a stock manifold that I had ported and a Cobalt Addiction 2.5 DP w/ Cat.

I received an Intense Brand Prototype Shorty Header (they sold it to a buddy of mine a couple years ago, when they were finished testing it..or something like that).

I was going to have to fab up a down pipe to bolt the header up anyway, so I took this opportunity to add a cut-out to my car.

Anyway, when changing it all out, everything went smoothly, I noticed that the Upstream O2 sensor was a bit warped from heat, and figured I'd have to buy a new one soon. Finished making the dp and bolting it all together at sometime around 4AM sunday morning and take it for a drive. Where all goes well until i make a 40-120 pull. When I get off the gas the afrs never lean back up to cruising levels and my scanner is showing a flat line full lean reading from the o2 sensor. No big deal, I assume the nearly dead O2 died off and save the project until I've gotten some sleep.

The next day I go get a new o2 ($132 ) and install it. (Side note, the end was GONE off the stock one)


Fire it up, car runs great.. one of my buddies wants to go for a ride. So I make a similar 40-120 and the new O2 sensor flat lines.. (Fortunately Advance Auto was willing to swap with me.. or I would been at $264 on the day..*twitch*)

At this time i deside to examine my header's design .. The bung for the 1st O2 sensor is a good 1.5-2" closer to the head than it is on the stock manifold. The car this came off of never had the problem, but it was just stage 2 so it's not making near the egt's I do, I don't believe.

So, we deside just to screw a plug in that bung and add another just past the flex in my downpipe directly across from my wideband sensor. As a safety measure we space the bung out as far as we can before welding it in (this comes into play later, I think). Fire the car.. o2 sensor lives this time.



Here's all the confusing stuff and questions:

1) The new O2 sensor only fluctuates from 700mV to 780mv instead if 200mV to 1000mV (the car is actually holding a tighter idle and cruise afr because of this, but it popped a code from insuficient fluctuation). Could this be from spacing it out further than stock, or from moving it further downstream?

2) I get some occasional crazy readings out of my wideband, that I'm wondering if they could be turbulance from the cut-out that starts just past it. If I let off the gas from a cruising state, it will go into the 12.0-12.5 afr range for a good 3-4 seconds before it registers that DFCO has kicked in and it goes lean like it's supposed to.

3) I didn't expect to have to retune much, if at all, for adding the header but it went 3/4 to a full point lean under cruising, I ended up richening the car from 1500hz to 6000hz (MAF only tune), as a band aid and safegaurd until I can see if i can find another problem in the mix.

4) Has anyone else had a problem with a shorty header eatting O2 sensors, I suspect that since this is a prototype header, it's not exactly a refined design..?

5) Uhhm.. anybody got any cookies?.. Cookies make me feel all better..

Random Header/DP Pictures



We actually made another piece that bolts on to the cut-out that turns it back, but i don't have a picture


Hot Parts Suck

 

Sucks bro. I'm having similar issues with my vibrant exhaust right now, but it isn't eating up sensors. But maybe I should take a look at my front o2. Take a look at the codes that are setting for now. Lsjwannabe gave me a few ideas to try out. Pass things by him if he doesn't see this.

 

my front o2 on my Jason Smith header is located on the 4th cylinder about 6 inches from the head , not at the collector like all the others are. No idea if my tuner had any issues because of that though.

 

bump

 

Ive got a GMRacing prototype header, and i am currently having issues with my B1S1...my problem is ambient temperature related though.....yesterday it was 85F and I set a P0172 and today its 68F and I am runnin +3 - +8 LTFTs My sensor is in nearly the same spot as yours though, and I still am not having any transition issues, in fact ill rock from 950 all the way to 20mV, LOL. I am just rambling and contributing nothing of value.

Your insufficient transitions is almost certainly due to the sensor being isolated from the exhaust stream too much. Disconnect and make sure it still goes back to 450mV.

 

Unplug it and it should read 450mV? Is that what you're saying?

Additional Info: When Idling the O2 will transition as normal, then when the rpms pick up, it starts reading as stated above. Perhaps the slower moving exhaust is easier to read than the faster moving?

Thanks a Ton Maven.

 

Wish I had more insight to give you than I did the other night

 

Yes an unplugged 02 should read 450mV(+/- 5 or so is fine)

An plugged in 02 sensor out in the air should also read 450mV

 

More information still: It's ticking, like a header leak... Could explain the leaning out if it's been doing that all along.. I can't find the leak with my stethoscope though, so I don't know if i'm actually hearing a leak, or it's just the thin walled header that sounds different..

Gonna pull the pipe down this weekend hopefully, and file down the bung for the o2 sensor and see if that gets me a better reading..

Meh

 

I had the same problem and i just put a spacer on the O2 and haven't had a problem since

 

You put a spacer on an O2 sensor that wasnt transitioning from lean to rich and it cured the problem? You sure you arent talking about putting an antifouler on the #2 sensor to make it it less sensitive to setting P0420s?

 

The ticking is a leak at the header. Has to be. The header wouldn't tick unless it was rubbing somewhere

 

Scanning without the car running the O2 reads 458mV.. i'll call that good

 

yeah, thats good. lets you know the circuits have the proper resistance(most likely) and the sensor isnt shorted or otherwise damaged.(most likely )

Sounds like placement is the big issue with your static output voltages.

 

placement is key on this it seems.

I want to comment on your mention of thin walled exhaust sounds like exhaust leak, would header wrapping help that? i have wrapped headers before and it has never lasted due to corrosion. I wonder is spray painting, then wrapping would help prolong the piping.

 

I would imagine that wrapping would help, but, it still eats the tubes, even with paint from my experience

 

UPDATE: Pulled the whole system back off this weekend, new gaskets. Found a crack in the header that we welded up.

Reworked o2 bung so that the sensor is in the correct dept now. It seems to be reading better, but it's still not "right".. HPT is also picking up an immature o2 heater error (meaning it hasn't done it 3 starts in a row yet).. wonder if i just got a bum o2 sensor?