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O2 issue after new axleback

3K views 37 replies 5 participants last post by  Spykexx 
#1 ·
So I finally got my gt500 axlebacks put on and now I'm throwing constant codes. Bank 1 sensor 1. It keeps getting stuck rich then immediately stuck lean. Then it will settle out and read fine for 30 seconds. Then bam 1.52 for 10 seconds then .71 for 10 seconds. This just repeats.

I've changed o2 sensors to no avail. And this start exactly at the same time I had my ABs changed. But i just cant imagine changing mufflers would cause any kind of issues like this.

Any ideas?
 
#3 ·
I was fixing to tell you, "axlebacks have nothing to do with the 02 sensors" :). Happy you got it straightened out :)
 
#5 ·
That is a weird coincidence. Who made (Chinese) those O2 sensors you put in? Are there even other options?


I'm asking because this a mod I want to do in the very near future. Probably not the same mufflers as you but some sort of axle back upgrade.
 
#6 ·
They are japanese. NGK from American Muscle. I believe it was just merely coincidence. Axlebacks shouldn't cause any issues that far up the exhaust.

Anyone else happen to have issues where only one side on your long tubes is blowing O2 sensors quickly? I've heard all the stories, but mine only seems to happen on bank one. Still running stock one from the factory on bank 2.
 
#9 ·
Did the wiring happen to come undone or become damaged?

The oscillations are odd. It seems like the computer is trying to correct, over correcting, then trying to correct the other way, over correcting, then trying to correct back the other way... It is getting a goofy reading from somewhere.

Which o2 sensors are you changing, front or rear? Are the trims in bank 2 stable?
 
#10 ·
Yea seemed odd to me as well. Usually a dead o2 will only read one way. This one reads fine about 50% of the time then it seems like once I clutch it freaks out. Any tune, replaced with new sensor and did same thing. So I figured something was screwed.

Swapped banks last night and bam it followed. Seems like a sensor issue
 
#13 ·
When you remove the sensor is it heavily oxidized? Could be a bad cylinder on that side. Maybe do a leak down test on that side and see if you have a bad valve? Give us all the details you can, Spykexx.

Sorry, don't mean to be a bearer of bad news :hide:
 
#15 ·
What's strange is it doesn't seem to really kill them. They just start acting strange. They will read correct 60% of the time or so. And then they freak out and max lean/rich then read perfectly fine.

They are pitch black when removed
This is not a good sign, bro. Are they coated? Do you remember, when you put on the long tubes was the original O2 sensor pitch black? These days, on a properly running engine the O2 sensors should be a chalky gray to black. Sounds like you have a rich condition thats fouling the sensor. Could be a faulty valve seal at a cylinder on that side, or you may need a custom tune depending on the mods you've made.
 
#22 ·
I agree sadly. :/

I changed out the bad o2 sensor just now that was swapped to drivers side and stayed on the sct time for now. Everything is staying in range. A little rich because of being a canned tune but seems to atleast slow down damage. Once that one was swapped out it made the other bank stop freaking out. So after taking a look at then they were pitch black. They were dark but not black black.
 
#23 ·
If it was the tune I'd think both sides would behave the same way. since its just 1 bank I'm thinking bad valve seat or seal. One thing you can do is pull the header on that side and examine the exhaust ports. The trouble cylinder (if you have one) will be obvious by the amount of oxidation.
 
#25 ·
Just had a thought Spykexx. I wonder if you could have a bad injector. An injector that constantly leaks fuel into the cylinder would cause a rich condition that the computer couldn't compensate for. Pull the plugs for that side. The jet black one is your problem cylinder. Try replacing the injector and plug for that cylinder.
 
#28 · (Edited)
Brings me to another Issue that may have something to do with it or be a symptom? I am getting pretty atrocious gas mileage. On highway I get around 18-19 @ 70. Don't even ask about in the city. I have been driving it like an absolute baby. ZERO acceleration pulls. and I still can't get anywhere close to even 20mpg. This has been the situation since I bought it and throughout about 4 different tunes. So seems to be something other than the tune.

I just wrote it off as driving it like a bat out of hell. But For the last 3 or so weeks I've been driving very conservatively and have seen absolutely no improvement in fuel usage.

_______

Edit: I've also thought about having the bungs moved up much closer to the head on the rear cylinder for both banks. Seems to help and keeps borla from having issues.
 
#33 ·
Well Spykexx you're right. Ford took a simple task and turned it into a PITA. There is a lot of info out there on this (youtube vids) doesn't look too difficult and I believe the intake gaskets are re-usable. Good luck and keep us informed on your findings.
 
#35 ·
Thanks Volt I figured as much, but sometimes for jobs like this the community will have tricks for doing it simpler.

I remember the manual called for my engine to be removed for changing my alternator in my 3000gt. Holy god what a pain in the *** that was, but with community tricks it goes from a nightmare to only an 8 hour job -.- Same thing with rear bank spark plugs. They were set up against the firewall.
 
#36 ·
So I talked to the woman, and we think we're just going to go the route of buying new. When I decided to get into the mustang scene(I'm generally a german/import guy) I really wanted an S550 in competition orange. We seen this S197 in passing and we both fell in love with it, and the price was definitely right.

But I think instead of trying to sink anything more into this one, just trade and buy brand new seems more fitting of what we want atm. While the VA is still paying me a hefty amount we figure we might as well put that into a new car with a warranty and essentially get it free.

We go tonight to talk to our local clubs dealership that sponsors our club about what we can get for trade and how much we can get a 2017 Grabber Blue EBPP.
 
#38 ·
I have two probables. As you guys said. Head/valve/ring issue (This could be very probable as I also have miserable knocking issues as well. We thought they were false but even after going to the shop multiple times they can find nothing to create false knock. So it's very well possible.)

Or that these headers just suck THAT bad. I have read a couple accounts of people having miserable luck like this with the BBK long tubes. Replacing like monthly. Quite a few moved the bung to the rear cylinder tube and had great success as Borla does this as well.

It spans across every tune (I have 3 different brands and different octanes.). All new O2 sensors from NGK. The one side is obviously running rich. I just can't justify dropping a bunch of money to figure this out on a car that is used, PROBABLY had this issue before trade in and is why they traded it in, and if it IS a head/valve issue dropping the amount of money necessary to fix when that's all that will come out of it. I might as well trade it while I can still squeeze a good amount out of it.

The VA pays me quite well to go to school, so I might as well utilize that for a free brand new mustang that I really want, or that's how I see it.
 
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