Problem!

[TheEdgeofSanity]

its got gremlins, yo

[[ion] C2]

[misslindseysue]

Rough surging idle is probably a vacuum or intake leak. Check all your hoses and spray some carb cleaner around all the connections on the intake side. You'll know when you find the leak.

[DOHC_tuner]

dumbeff? Watch that mouth boy....u seem to like to talk shit. You dont need a lift to change the O2 sensor. Although I do understand if its your daily driver, so just say that. Dont be a punk who needs his ass handed to him by me!

[[ion] C2]

... >: )

I don't have a good jack on me either, and lifts are effing awesome.

[[ion] C2]

http://www.j-body.org/forums/read.ph...23791&t=423791

Anyone have any further insight? Today we're putting the rear O2 back in, and moving the upstream O2 closer to the head, back in the collector where Pacesetter's location is. I'm also having him replace the butt splices on the O2 wire to being soldered.

[CactusWill]

The ONLY thing the rear O2 sensor does is tell you if your catalytic converter is good or bad. So that alone is not going to make any difference, all it will do is display your check engine light or not.

[Gr1m]

its a vacuum leak from everything that you have said, unless you were tuning it improperly and that could cause the symptoms your describing

[[ion] C2]

Someone's saying that it should be closer to the head, like in one of the primaries.

Also said BOSCH made him have an issue like this, switched to ACDelco O2 and it ran fine.

I put a BOSCH in.

[[ion] C2]

On GAGT everyone's talking about how BOSCH sensors are garbage and cause this kind of thing, but this problem existed before I replaced it, which leads me to believe it's not the O2 sensor itself, but some other physical problem such as the location.

From other automotive forums:

Something everyone seems to overlook when talking about that rear O2 is that it DOES affect your fuel trim, aside from monitoring the converter.

And the reason the measurement is inaccurate the farther you go away from the head on the upstream O2 is

Further from the chamber, the reaction is more complete.

This guy says the tune is made for the OEM O2 placement.

Should I put it in one runner (closest to OEM location) or in the collector (farther away but all runners' input)?

[[ion] C2]

Some interesting info that provides more evidence that the rear O2 is used for more than catalyst monitoring, it also controls a bit of the fuel trims:

http://newsgroups.derkeiler.com/Arch.../msg00732.html

I'm hoping the repositioned O2 and reinstalled rear O2 solve it. If not, I'm redoing my VE tuning and that should fix it.

[guiguilandry]

don't put the o2 sensor into one primary, you'll only be monitoring only one cylinder. it has to be in the collector/or in the exhaust farther, if this would be placed in a primary, how the computer could possibly tune all 4 cylinders ??? It adjust the AFR with all the collected gas of all the cylinders

[[ion] C2]

Yeah I'm putting it in the collector, and the rear O2 back in, and having the butt spliced wires soldered.

[guiguilandry]

personally, I don't think that the removal of the rear o2 sensor is the problem... On my car when I custom did my wiring harness I didn't even rewired this sensor !!!! I have no cat either I just deactivated the codes with my DHP Pwrtuner. The car has always ran great.. even when I first started it without the reprogrammed pcm...
You will reinstall it and it will set a code, this will not help because you won't still have a cat and the o2 readings it will see will be way too rich... IMO

[[ion] C2]

I have a cat... and the codes are disabled... We removed it because it was in stock size piping, I figured we'd save time and not weld in a bung for it because I deemed the sensor worthless.

Supposedly it's not.

[guiguilandry]

... maybe if you remove only the catalyst efficiency codes and let the heater on ....

[guiguilandry]

sorry I thought you didn't have cat

[guiguilandry]

you'll let us know if that will fix the problem

[[ion] C2]

Yeah all codes relating to the downstream O2 are set to no SES and "No Error Reported"

I'm going to go do all this stuff in an hour or two, will let you know what happens.

If this doesn't fix it I'm going to clean the IAC and throttle body as well, and search harder for vacuum leaks. If that doesn't work I'm going to Speed Industry (guys who are building my spare engine) and see if they can figure out wtf is going on.

[[ion] C2]

No vacuum leaks.

We couldn't move the upstream O2 any closer, not enough room to weld, and we weren't gonna pullin the header off, or put it on only one of the runners, bad idea.

Welded a bung behind the cat and put in the rear O2 and reconnected it. Also soldered the upstream O2 connections for the wire extension instead of the butt splices. Still no difference.

But now it's honestly not that far from where the collector is.. (This is the wideband, but the primary is on the other side, basically same spot)



There's no room to weld on a bung while it's on the car, unless I put it in one of the runners but that's not really a good idea.

It seems like it's misfiring, and the exhaust sounds like it. I realized I did something the day I went to get the header on. Just before, I changed out my IDI cover. Last time I pulled off my IDI cover one of the springs in the spark plug boot came out and was laying on the head, making me run on 3 cylinders. I figured I screwed it up or it wasn't on right so I took it off about an hour ago and put it back on, everything should be aligned and connected, but no change.

This totally blows. Could be anything. Simply plugs (checking tomorrow), coil pack finally needing change, head gasket, exhaust leak before O2, or the O2 sensor being farther away from stock. There's no way to put it in the collector and have it be as close as stock. Also as pictured above it's not that far away from the collector.

I don't know what it is...