Running lean on hot startup

2012+ US/Canadian Civic Si / 2013+ ILX
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schaffertnathan
Posts: 19
Joined: Thu Jun 28, 2018 6:31 am

Running lean on hot startup

Post by schaffertnathan »

Cranking AFR while hot is good, but then after a few seconds the idle leans out quite a bit.. To around 17-18. It does Not do this during cold start after car has been sitting for few hours..only does it when the engine is still warmed up. I tried adjusting Cranking Fuel Trim on calibration tab and also the Cranking Fuel Table, those did not help. I tried the IAT cranking fuel trim and that did not work. The IAT was the same from when I was driving and didn't show any signs of heat soak, so I didn't bother adjusting the IAT fuel comp. The lean condition only lasts about a minute and then the AFR comes back down to normal. What else could be causing this problem?

EFICU
Posts: 156
Joined: Mon Feb 25, 2019 10:14 pm

Re: Running lean on hot startup

Post by EFICU »

What are your fuel trims at idle during normal stops at a signal light or whatever?

Do you have a datalog you can post and your tune file?

Let us know and we can try and help. Feel free to PM me the tune file if you don't feel like posting it on here. But at least post the datalog so others can look at it.
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schaffertnathan
Posts: 19
Joined: Thu Jun 28, 2018 6:31 am

Re: Running lean on hot startup

Post by schaffertnathan »

I don't have O2 sensors, just a wideband gauge. So it doesn't show AFR in the datalogs, but I'm running 14.7 during normal idle. It's only the first minute or so after hot start that it runs lean

EFICU
Posts: 156
Joined: Mon Feb 25, 2019 10:14 pm

Re: Running lean on hot startup

Post by EFICU »

Interesting. Okay, do you have a datalog and tune file we can see? Without knowing what seeing what you have in the file it may be difficult to pinpoint. Someone with more experience than myself may have a better idea.

I guess the other question is, are you boosted or what? How come you decided to delete the O2's?
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schaffertnathan
Posts: 19
Joined: Thu Jun 28, 2018 6:31 am

Re: Running lean on hot startup

Post by schaffertnathan »

I will datalog a cold start and a hot start tomorrow and upload the files.

I'm on E85, so at first I thought that I couldn't use the factory O2 sensors with E85, but now I've just been too lazy to put them back since I have the wideband. I also have the Skunk2 catless downpipe

EFICU
Posts: 156
Joined: Mon Feb 25, 2019 10:14 pm

Re: Running lean on hot startup

Post by EFICU »

Gotcha. Okay, yeah post what you can when you can and we can take a look at it.

Like I said, some people who know a lot more than I do may know right off the top of their head. Hopefully they chime in if they can. I would need to look at the data to be of help.

let us know.
EFI Calibrations Unlimited

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