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I have a 2017 Fit, with short ram intake, RV6 catted DP, exhaust, Ktuner Stage1 tune. I decided to port the stock intake manifold. After reinstalling, the car is running 18.5 AFR at idle where she was previously 14.7. I got a lot of check engine lights. I only drove her a mile, WOT was fine with 12.6 AFR like usual, she's idling rough. Is it safe to drive around and see if the MAF "relearns?"

If I want to add fuel at idle, what is the best parameter to modify, in what table? Cheers, d'Art

RE: porting: There's not a lot to port, but there was definitely a weird restriction right after the throttle body, kind of like a plastic K right in there. I cut that out completely, then dug in with a die grinder, and then finished by hand smoothing with various sand papers. I ported each intake runner about 1.5" also (as far as the die grinder would go) and then hand sanded those too. There was also a shark finned metal protrusion attached to the engine block that must have something to do with EGR that comes in on the underside of the intake manifold just after the neck. I definitely wanted to cut that off completely, but decided to do this in stages. Also the TB is circular on the inlet and outlet, but the intake manifold is oval shaped at the inlet. I figured I could port the throttle body as well, but again, I figured 1 change at a time would be best.

This is a mass airflow vehicle. It wouldn't matter if you port the intake manifold, the air would still get metered and the appropriate amount of fuel delivered for it. You either have an intake with an improperly designed MAF housing, a vacuum leak after the MAF which is allowing unmetered air in, or the MAF sensor is dirty.

Thanks for the quick response Ktuner! I left a more specific question regarding my ECU part number and tuning in the 3rd generation Honda Fit section.

I did a drive up and down the freeway with the least street driving I could do, turned the AC on and off, all the gears. It still runs great everywhere except stop lights. At one stop light it started smoking so I went home and that is when I sent in the questions.

After your obvious reply, I got some throttle body cleaner and attempted to spray around a bit. It revved the air cleaner element, so I thought I would be able to find the leak similarly. The smoking got real bad real fast so I decided to just pop off the IM and see if maybe one of the gaskets came off a runner etc. After the short ram intake came off, the throttle body looked a little oily. Whatevs. When I took off the intake all this oil came out of the intake, probably like a half cup. What could be causing the sucking in of that much oil?

While I had the intake off for porting, I pulled the valve cover off and checked all valve lash too, that was easy and presumably non-interference. I am thinking it must be something I left off or plugged up but I can't see it. There are two hoses that go to the intake, one from thee brake diaphragm, one to the block (lPCV?), A third hose goes from the valve cover to the short ram after the MAF, before the throttle body. Any advice is welcome regarding where oil can come from and into the intake. Cheers!

I got the AFR back to normal, probably over tightened the IM or TB. I took the IM Car is still smoking but I only went around the apartment once. Gonna go for a longer drive and see if the oil burns off...

Smoking stopped too. I washed the IM with soap and water and blew it clean with compressed air. Put the IM back on and went very light with the torqueing, and she's back to normal. Car has a bit more throttle response with the ported IM. Cheers!

That's great!