Hello everyone.
I'm thinking about buying a new 9th gen si!
Always wanted a peppy civic.

Is LTFT at -14% on a cold start (i.e. go to the grocery store around the block,and start it after you get out), normal?
This particular civic has an exhaust mod that is an outlet before the muffler. Some kind of custom setup I guess.
I'm wondering if that will trip up the 02 sensor and make it run rich on startup.

This isn't the first time I've seen that sort of fuel trim on a k-series engine on startup.
It goes back down to normal after running it around the block relatively hard.

Thanks!

 

So, you are saying that your fuel trims (STFT and LTFT) are pulling fuel while the engine is warming up, and get close to zero once the engine is warmed up ? If so, then there is nothing to worry about at all. One could adjust some cold start fuel trim values to keep fuel trims closer to neutral, but you need a tuning solution to do this.

 

Thank you.
It's LTFT only at -14%, after a quick trip around the block and after sitting for a bit.
STFT is at -3ish%.
That's what confused me.

After running it around for a while and hitting v-tec a couple times, it all goes back to normal -3-4% at both LTFT and STFT.
All other civics I've looked at were -3-4% always, regardless of how cold the start was, and what was going on.

 

There is a possibility that you may have a problem with the fuel pressure regulator in the pump assembly... this would cause a rich condition at or near idle engine speeds, however, fuel trims move closer to normal at medium and higher engine speeds. It is an easy fix... and a genuine OE FPR is less than $150.