Wandering afr

[PunkST]

Checked at idle. For the brief times ( only like a second) where its 14.70 commanded my stft is zero. It floats between -2.5 all the way up to 3.3 on the stft with the car just sitting. The commanded also moves around a little. Like half a point so my guess is thats all normal.

 

[TDavis]

Mine jumps to 16~ for a split second and goes normal but its only on cold starts when its really cold outside

 

[Jason@dizzytuning]

Mine jumps to 16~ for a split second and goes normal but its only on cold starts when its really cold outside

Because commanded is 15.7 on cold start.

 

[Westley117]

I know this is an old thread but I'm also having the same issues with it going back and forth between 13 and 15. I've checked every possible vacuum leak, I've changed out the purge valve, canister, entire evap harness. While driving it stays within the 14.7, 14.4 range. It's driving me nuts!! There's little to non Information about it ether which does not help.

 

[TDavis]

Yeah mine still does it till this day. If I'm at constant throttle it'll wander until the engine is fully warm but if I let go or get on the gas it stays where it should be for a few seconds then back to wandering.

Maybe o2 sensors 🤷

 

[TyphoonFiST]

Put the Anxious port AWAY* and Drive the FIST. This is a rabbit hole that you don't wanna travel down. LET IT GO people.

 

[Westley117]

Yeah mine still does it till this day. If I'm at constant throttle it'll wander until the engine is fully warm but if I let go or get on the gas it stays where it should be for a few seconds then back to wandering.

Maybe o2 sensors 🤷

I've actually replaced the upstream one and nothing has changed so that's been crossed out.

 

[Westley117]

Put the Anxious port AWAY* and Drive the FIST. This is a rabbit hole that you don't wanna travel down. LET IT GO people.

I do enjoy it but I also want it to run properly. I plan on doing more track days and I don't want it to run poorly and end up causing something catastrophic

 

[TyphoonFiST]

I do enjoy it but I also want it to run properly. I plan on doing more track days and I don't want it to run poorly and end up causing something catastrophic

You worry way way too much. If its been flash or pro tuned it will be fine. If you really wanna monitor stuff ...When you change the oil send in a sample to Blackstone laboratories to monitor the health of the engine. A better allocation of your worry thoughts.

 

[Westley117]

You worry way way too much. If its been flash or pro tuned it will be fine If you really wanna monitor stuff ...When you change the oil send in a sample to Blackstone laboratories to monitor the health of the engine. A better allocation of your worry thoughts.

Yeah I guess you're right. With it being my only mode of transportation and having a history with a problematic car I'm just trying to keep it running properly.

 

[TyphoonFiST]

Yeah I guess you're right. With it being my only mode of transportation and having a history with a problematic car I'm just trying to keep it running properly.

You will be fine....Just enjoy it. Your not BT...4 port Aux like myself....Even my tuner said...Just put the Anxious port in the glove box. If there is something NOT feeling right take it out and record a log and send it to me.

 

[TDavis]

I understand the term "Anxiety Port" but it has helped me find and solve subtle problems before that I wouldn't have known about if I didn't have it up

 

[thecman02]

Every value you guys have been talking about is very normal behavior. I'll post a few bullet points.

1. Both exhaust sensors the lambda and regular heated O2 sensor need a minute or two to get up to operating temp to even read accurately.
2. When the car is first started up it will usually be in an open loop state so the afr's should be fairly stable minus the sensors heating up and more accurately sitting on commanded value.
3. This AFR wandering you see is an emissions control strategy. The ECM has algorithms designed to keep the catalyst "lit". When it drops below temp from a calculated amount of time from an enrichment or high load state it will bounce the AFR in a sinusoidal rich to lean state. The rich "lower than 14.7" phase feeds the catalyst (cat) fuel. Then it goes lean to feed the catalyst air.
4. So catted cars literally can't sit at lambda or the cat will only be exhaust temperature, which is too cool to scrub emissions from the car.

Moral of the story is listen to the people telling you to put AP away if you don't have trouble codes and aren't tuning/having issues.

 

[TDavis]

Well I don't have a cat. Also, mine didn't do this before lol. I'm not worried about it. Just figured it was odd behavior.