O2 readings

For those of you that have used tech stream live monitor function what do you make of this? I’ve attached my current readings that were done while the truck was at operating temperature. I’ve used techstream for several different things but this is my first time monitoring the o2/af sensors. Is there one that seems to be the culprit strictly off the data? I appreciate any info.

 

Something is going on there particularly with bank 1.


Got any backstory here?

 

Just a lingering CEL. I was wondering if this is the simply the sign of a failing b1s1 sensor or possibly something else. It’s probably about time to replace all 4 but it’s an area I need to familiarize myself with a little better bc I do all my own maintenance on 4 vehicles but never really had to deal with these. I pulled all four just to inspect and the resistance was good on all 4 but like you said something is def wrong there.

 

Need to run it long enough to get the downstream sensors to come online then we can see if the upstreams are lying.

What code(s) do you have?

 

She’s been throwing 420/430 off and on for the last month or so. I’ll erase the code and it’ll stay gone for a couple days then usually return. Answer me this please, if that upstream is bad why will she run for a day or two before throwing the code again instead of immediately? Also my bad, I figured I had warmed it up enough to get a CL reading. I’ll run it again tomorrow right when I get off the road.

 

That may be a separate issue but wee need to see what's up with the bank to bank imbalance before chasing the catylyst efficiency codes.

The catylyst monitor isn't a continuous monitor, it only runs after the AFR and O2 monitors run & pass and only during specific driving conditions. P0420/430 is >90% of the time failed cats but occasionally an exhaust leak, failing AFR/O2 sensor, or something else causes them.

Toyota delays turning on the downstream O2 heaters for several minutes after startup even if the truck is fully warmed up so it can take them a bit to become active.

Just for reference this is what a known good cold start looks like although yours probably won't have the lean spike at the beginning because it doesn't have SAIS.

You can see the quite long delay before the O2 heaters turn on and the sensors wake up.

 

Ok. I know I can count out an exhaust leak, I ran through all that a while back and changed all the gaskets. When should I run this monitor again, upon start up or after she’s good and hot? I’m ignorant in this aspect obviously hence the questions. My other rig is a 98 land cruiser 330k miles so these two don’t have many issues thankfully but I keep up maintenance pretty well.

 

Cat activity needs to be checked hot but I'd want to log a cold start and see what things do then you can log a drive and see what you have.

I think we may be dealing with 2 separate issues but definitely need to see what's up with the fuel trim imbalance before chasing the catylyst codes.

 

does your exhaust reak of unburned fuel? if so you could have a clogged injector. Your short and long fuel trim in bank 1 is pretty high coupled with the imbalance between the 2 it seems you have a issue that could lead to fouled cats. Get some readings with your system hot.

 

This...
But anything can be the cause, needs to be accurately & correctly diagnosed...
Could be a simple as faulty or dirty MAF sensor...

 

Ok will do. I’ll be leaving out in a hour.5 so I’ll get it then. MAF was cleaned two weeks back, I clean it every 3-6 months or so. No obvious fuel smell.

 

Bad Maf sensor would affect both banks, not just one side..

 

Here’s the readings from a cold start this morning. Excuse the typical tacoma tensioner pulley squeak, we got rain last night. It’s next on the list to swap out.

 

Hard to see the rest of the pics but the first pic everything looks pretty good, not sure what the deal was with the lean reading on bank 1 in for first post.

I'm not familiar with how techstream works but you can't do several graphs over a longer period of time?

 

I’m sure you can I just haven’t sat down and figured it out yet.

 

I mean it's pretty hard to make a determination for the things we're chasing by looking at a couple frames of scan data. Really need to see it on graphs like in the screenshot I posted but I don't know if that's possible to do in techstream though.