I hadn’t gotten a response to my other thread so figured I’d directly address this question.

I installed the anti fouler fix for my P0420 code. I used the two foulers stacked on top of one another as recommended by many.

My CEL has stayed off (for now) but I have a noticeable loss of low end torque. It’s not huge but I definitely have to push the pedal further to get and maintain power.

I’ve been told the down stream does not affect fuel trim and air/fuel. But read somewhere else it can account for some fuel managment.

Anyone else hAve this experience? Is is because maybe the o2 sensor is spaced to far? I don’t want to run lean or damage my engine.

Thanks

i'm no expert but o2 spacers shouldn't cause any engine performance whatsover, in fact the main reason you run them is to trick the ecu that everythings fine in case you are having cat converter issues, running headers among other reasons.

Did you erase the codes after installing the spacer? I'd say make sure your o2 sensors in general are ok and disconnect the battery for a few minutes.

Could be a relearning process for the ecu but I highly doubt it.

Looks a lot like a clogged cat issue tho.

Agreed. Doubt that the foulers are causing this.

@miller507

This is what I thought but I’ve read somewhere that the smaller range of voltage that the downstream maintains can affect the feedback loop that the ecu uses to set afr at different throttle positions. Any other insights would be great. It’s like the first .5-.75” of the gas pedal is totally dead.

The only other thing I’ll say is I had a mechanic replace the upstream sensor the other day in pursuit of curing the p0420. It didn’t work, the code came back and I didn’t notice anything performance related then. I noticed right after the fouler fix.

@importman

That’s what I thought. I guess the only way to check is to take the fouler out. I’m on a trip drove 500 miles to Vermont. Definitely noticed a difference on hills. It’s upshifting all the time. She never did that before. Ever.

Could it perhaps be since the flow is blocked to the sensor it’s changing the ECU parameters for throttle sensitivity? I tired unplugging the battery to reset. Immediately after doing that there seemed to be an improvement but it only lasted for maybe a couple of mins. Seems like the reset may of brought back factory settings but the ECU quickly relearned. It seems from a stand still to be mostly ok, it’s applying throttle while moving - I have to depress almost a full inch before I get throttle response. So annoying!

Someone’s got to know what’s going on. I have a sneaking suspicion that the downstream sensor does have something to do with AFR or sending back info to ecu on air flow to adjust throttle, etc.

unless you're throwing engine codes it's highly doubtful that any close-loop feedback from the downstream sensor is causing what you're experiencing.


When you say you had the mechanic change the up-stream sensor while working on curing this issue originally.... is that replacement sensor still in there..?


ps: Like I mentioned in the other thread.. I've been running this work-around for over the past year with no CEL or change in throttle/performance, etc. This being a very common solution would probably have resulted in regular feedback from other if this was related to the downstream o2 sensor spacing... just my thought..

Installing anti-fouler fixes to correct a P0420 code can have unintended consequences, such as the loss of low-end torque that you have experienced. The down-stream oxygen (O2) sensor can have an impact on fuel management and air/fuel ratios, which could contribute to the loss of power. It's possible that the O2 sensor is now spaced too far away due to the anti-fouler fix, which could be affecting its readings. I would recommend having a professional diagnose the issue and determine the best course of action to avoid any potential damage to your engine.

I would install the torque app and record the B1S1 , B1S2, B2S1 & B2S2 voltages as well STFT & LTFT graphs vs trying to web guess the solution.



Sent from my SM-G981U1 using Tapatalk

Take the spacers off and see if the throttle performance returns.

If it doesn't you likely actually do have a clogged cat.

That is an excellent advice and easy to do. P0420 often gets a bad rap for "shooting the messenger" when the cats are indeed clogging up. But, the O2 sensors get the blame!

Cats are easy to clean with some muriatic acid and hot water. Just do a search on YT on the process. Clean your cats, save a ton of $$$$!!!

I was thinking the same thing

You're an idiot and a shithead link spammer. That's not how any of this works.