DG_

Just did a datalog on my car and it shows the ecu is pulling A LOT of knock; see attachments.

Could this be just bad gas (always fill up 93 at exxon or shell) or could something else be causing this problem.
I'm currently running o/r x pipe.

Ditty

Are you running a tune on the car? If so, I would data log a lot and then send them to your tuner.

DG_

Stock tune at the moment.

scottmach

Why the heck are you running an off road x-pipe and no tune?

Ditty

THIS is the source of your problem. It's required to run a tune if you delete the cats.

DG_

TBH I thought the same thing, but the tuners at BAMA assured me it's ok to drive without a tune. Basically saying that it'll run just a bit richer and the cat cells would come on.

That was a month or so ago. I now was planning on getting a tune from another tuner, but once I showed him the datalog, he said that either I'm running bad gas or there might be another issue going on and that he can't tune it while this is going on.

I figured I would post here, seeing if anyone else has any insight of what might be causing this issue.

Ditty

W/ out the cats, the car thinks that there is something wrong. You HAVE to have a tune to turn the down stream O2 sensors off if you are running cat-less. I doubt someone at Bama or AM told you that you can run w/out cats and w/out a tune. (not saying you're lying) Bama offers a catless tune for this reason. I'm surprised you don't have a CEL running cat-less.

Slowbra302

I would like a little more elaboration on this. I am running the smoothest performance tune right now I have ever driven. This thing drives smoother than the other two 5.0s I have driven, one tuned and one stock. The only thing is that bama forgot to turn off the rear O2 sensors so occasional it will throw a code every couple days and I jus clear it. Now I am emailing them as I type this to have it turned off, but HOW can just a couple of sensors inhibit anything with the motor. Now if they were the wideband front one, I could see that, but not the rears???

Thanks as always!

Ditty

All four of the O2s are wideband. I had a failed O2 on my DS downstream and it would cough and sputter until I replaced it.

With both upstream and downstream O2's on and NO cats, they are reading the exact same thing, so the ECU thinks that the Cats are bad and tosses the CEL and puts the car into a sort of 'limp mode'. The up and down stream O2's are not supposed to read the same thing, if they did (on an unmodified car) it would mean that the cats have failed.

Slowbra302

Mine still rips super hard after it throws the codes lol.... Nothing changes lol. Maybe bugged?.