i have tru duals on my 3.8. on the passenger side i have the header which has an o2 in the collector, i dont have a cat i have just pipeing which has an o2 in it then i have a o2 simm for the o2 that would be after the cat. if i tap into the o2 that is precat area will my gauge getan accurate reading since i dont have a y pipe which both headers flow the air through. i need my gauge to get an accurate reading but since each header has theiown pipeing i am not sure if the gauge will get a accurate reading

 

What you have to watch out for is not to tap into the wire between the connector and the sensor. Tap into the vehicle's harness prior to the O2 sensor connection. Also tap in to the pre cat sensor. If the sensor is prior to a Y pipe, you will only get a reading from that particular engine bank. So basically, you are only going to read what is coming out of that particular header. That is also what the computer is going to see as well. That might not be the best idea as half the engine's exhaust is not being read.

 

I knew someone would make me worry on this... zzp sells an air fuel pigtail that connects to the pre cat o2 sensor kinda like an o2 extension, the pigtail has a wire that the af gaige taps into.. so if you have to hook the gauge up to the egine wiring harness part of the o2 and not the o2 then how will the zzp pigtail work?

 

The pigtail would hook between the 02 sensor connector and the factory harness and would have a tap already there. You just don't want to mess with the O2 sensor harness itself. You are dealing with millivolts..... any lengthening or alteration can skew the readings. Besides that, you'll eventually need to replace 02 sensors anyway, this way you unclip and replace without affecting any taps.

 

so are you saying i should get the pigtail? i have o2 extensions because of my longtubes and it didnt mess any readings up, so what do you think about me having true duals ? will the af gauge get an accurate reading since i dont have a y pipe setup where both headers push exhaust down the same pipe? i hope i can use my af gauge/

 

OK..... ideally, your 02 sensor(s) should read the mixture from both banks. When you went to true duals and are only using one O2 and that is isolated from the other bank, you are only taking readings from half the engine. If the other half starts to go haywire, the computer won't see it and no adjustment can be made. That's why many V8s with have an O2 sensor at each exhaust manifold, or an O2 sensor after the Y pipe union so that all exhaust gases go through the sensor. Basically the way you've got yours done up, you've got problems just waiting to happen. It may work, but you are removing the computer's ability to sense and adjust mixture. Especially if one bank of cylinders starts to lean out for whatever reason, the computer might not see it and your pistons and/or headgaskets go south. It's not the 02 simm for the after cat that is going to hurt, it's not having readings from the other engine bank.

The rule with 02 sensors is that you don't mess with the portion that goes from the connector to the sensor itself. Any other plug in harness merely lengthens the engine harness and not the sensor itself. In order to mess with the sensor itself you would have to cut or tap into the portion that is between the connector and the sensor. As long as you don't so that, you'll be fine.

It is my opinion that you should re-think your setup. I have considerable experience with V6s and the gain from true duals is very small (and only at peak rpm) due to the amount of gasses being expelled. A well engineered single exhaust will flow as much air as open headers with better low end torque. This way you are not taking out built in safety measures that your computer has in place. As an example, my single 3" with two stainless ultra flows in line, flows enough for the car to do 129.2 mph in the quarter. Disconnecting the exhaust and just running an open downpipe, the car still ran 129.3 and gvies me a headache to boot. I would get a good flowing Y pipe and single exhaust over the axle and from there split it if you want, but you need to get the 02 sensor system operating properly. If that involves plugging the bung in the collector and having another bung welded into the Y pipe after the union, so be it. It is a necessary step and should actually improve your performance. Hope this helps.

 

i think you may have miss understood me, ok my exhaust setup is this

drivers side header with o2 in the end of it/the collector
passenger side header with o2 in the collector.

so i have 1 o2 in each header, it just the passenger side is the side with the pre cat o2 sensor in a pipe because i dont havea cat. but each header has its own pieping then goes into an x pipe into turndowns. so will my af gauge work if i put itin the pre cat o2 wire? even though both headers arent goingthrough the same y pipe . the only pipeing both headers runair into would be thex pipe. i am not spending hundreds of dollars on a custom y pipe, ihave longtubes which is theonly3.8 fbodywith them so the stock y pipe wont work i need to get this gauge to work

 

Gotcha... what you should do is run two seperate taps. One for each sensor that goes to a switch. That way you can switch the gauge between banks and get both 02 readings readings. You can't do both sensors at the same time unless you run two gauges, so the switch is what is used here. The gauge will work just fine, it won't matter where the sensor is as long as it is pre-cat. Understand that while the factory 02 sensors work OK, they aren't totally accurate. If you plan on tuning using the a/f gauge, a wideband (read $$$) sensor will be what you need for optimum results. If you just want to see a ballpark of what is going on, you'll be just fine.

 

i will use autotap to tune and i will also go get wideband o2 dynored. where could i get a wideband o2 sensor for a camaro? and would that sensor go in place of the precat sensor? with my autotap when i log the af its showing both banks right? ill justuse the gauge as a close reference

 

Most specialty distributers carry them. The autotap will give you readings of all sensors. That means you'll be able to see both 02 sensors and check for any bank to bank imbalence.

 

That means you'll be able to see both 02 sensors and check for any bank to bank imbalence.


that means the autotap would be easier for tuning with air fuel calibrator right

 

Yes, no, maybe, sometimes.... The autotap will give you digital readings. Sometimes these readings fluctuate quickly and it's difficult to see what is happening with accuracy. The readings stabilize at WOT, but are you going to read them? On a dyno perhaps, on the road doubtful. I actually run both. The digital gives me the readouts with accuracy at WOT, the gauge gives me an at a glance reading that's easier to read on the fly and quickly shows 02 activity and sensativity.

 

I could always press record when im autotapping and review it when i stop

 

bluecmaro96 is said you have long tube headers on your 3800 V6 camaro. What was your source? Did you fab them yourself? Did you have them fab'ed? Are they steel or stainless?

I am very curious because of the lack of choice in 3800 Camaro headers.

Regards,
Derek Cole

 

they are steel but are getting jethot coated, i got them from trading my rk suck headers and the one longtube needed work because it wasnt straight back like the passenger one so i had the drivers one cut and re welded so its more free flowing and the pipes are all equal length, i have decent ground clearance also, as long as i dont go on bad road