CEL P0301 came up today

[Sportsguy83]

I wanted to update I resolved my issues with the CEL P0301.

The closed loop/open loop transition in my car while running E85 was EXTREMELY rich, (AFR went down to 9) and this caused a misfire condition.

I asked my tuner to lean out the transition and now it only goes down to about 10.2, no more CEL.

This happened a few months ago but randomly saw this thread and wanted to let everyone know that may be your cause.

[s2d4]

Originally Posted by Sportsguy83

I wanted to update I resolved my issues with the CEL P0301.

The closed loop/open loop transition in my car while running E85 was EXTREMELY rich, (AFR went down to 9) and this caused a misfire condition.

I asked my tuner to lean out the transition and now it only goes down to about 10.2, no more CEL.

Was it in open loop or was it in close loop? Not entire sure what you mean by transition because it is either in close or open? or was the target/MAF scale incorrect?

Looks like plenty of guys have had this after a tune, they either get it replaced under warranty and someone bought aftermarket coilpacks and spark plugs instead...

[Sportsguy83]

Originally Posted by s2d4

Was it in open loop or was it in close loop? Not entire sure what you mean by transition because it is either in close or open? or was the target/MAF scale incorrect?

Looks like plenty of guys have had this after a tune, they either get it replaced under warranty and someone bought aftermarket coilpacks and spark plugs instead...

While cruising the car is in closed loop. When certain conditions are met (e.g certain load value, certain requested torque value, etc.) the ECU transitions from closed loop to open loop. That instant where the transition happened, the AFR would drop from 14.7 cruising to 9. It only happened in 6th gear (heavy engine load), and didn't need to go WOT, just partial throttle. So to answer your question, it was the instant it entered open loop.

[s2d4]

Originally Posted by Sportsguy83

While cruising the car is in closed loop. When certain conditions are met (e.g certain load value, certain requested torque value, etc.) the ECU transitions from closed loop to open loop. That instant where the transition happened, the AFR would drop from 14.7 cruising to 9. It only happened in 6th gear (heavy engine load), and didn't need to go WOT, just partial throttle. So to answer your question, it was the instant it entered open loop.

I thought it was load or throttle position.

Interesting, do you know what he did to fix the issue?

[Sportsguy83]

Originally Posted by s2d4

I thought it was load or throttle position.

Interesting, do you know what he did to fix the issue?

It might be only load or throttle position, I don't remember.

Honestly don't know exactly what he did, but I requested specifically to lean it out when it entered open loop. The tune stayed the same (meaning the conditions/situation to enter open loop stayed the same), but now instead of dropping to the 9's, it stayed on the 10's.

[s2d4]

Originally Posted by Sportsguy83

It might be only load or throttle position, I don't remember.

Honestly don't know exactly what he did, but I requested specifically to lean it out when it entered open loop. The tune stayed the same (meaning the conditions/situation to enter open loop stayed the same), but now instead of dropping to the 9's, it stayed on the 10's.

Maybe @mad_sb and @jamesm would have some experience with this and how they would deal with it.

[s2d4]

I think you have bigger port injectors? The scaling, duty cycle plus DI vs Port could have been an issue as neither of mad_sb or jamesm were keen on changing open loop fueling targets to fix stuff... Both of their reasonings were very sound.
lol, one of them basically implied a tuner was a crack head for using that method.

[jamesm]

if you're seeing huge swings in afr coming out of closed loop it's very likely to due a mismatch is fueling error between port and direct injection. or just bad maf scaling around 2.9-3.2v, as this area is pretty hard to nail down. i'd have to see a log or ask more questions to know for sure, but that would be my first guess.

[Sportsguy83]

Originally Posted by jamesm

if you're seeing huge swings in afr coming out of closed loop it's very likely to due a mismatch is fueling error between port and direct injection. or just bad maf scaling around 2.9-3.2v, as this area is pretty hard to nail down. i'd have to see a log or ask more questions to know for sure, but that would be my first guess.

At this point it doesn't matter anymore. I will get a new, different soon.