# Fuel trims with CAI?



## X-Ravin (Oct 6, 2010)

So I'm still tracking down some gremlins in my Goat. Started with a bad AZ MAF sensor pegging rich, cleaned the old MAF and now it looks better. Anyways, I'm seeing high LTFT's and I'm trying to figure out if they are something to be concerned with. The only mod that I know of on my car that would affect them is the K&N CAI.

I'm seeing all positive LTFTs, nothing negative. Idle is around +6. Cruise is weird because if I'm around 10-11% throttle I see +10, bump up to 12% or more and I'm at +5. Acceleration sees spikes up to +10, but is kind of all over the place in between. Note that I just reset the PCM last night, this is the 2nd drive with it. The STFT's seem to be agreeing with the LTFT's, aka they're oscillating around 0. All of this is with A/C on. Idle is closer to 0 with AC off.

So, am I having an external issue, or is this acceptable with a CAI? The MAF was cleaned yesterday so I think it's ok. I can attach the scan if needed.


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## svede1212 (Nov 1, 2005)

That means the car is running lean and the computer is trying to help richen it up. Make sure you don't have a leak past your MAF adding additional air with like something like you PCV tube or something. If you are sure the MAF is clean and you have no leaks I'd not go WOT until you get it tuned. At WOT fuel trims aren't used and it can go lean on you and possibly damage something.


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## Poncho Dan (Jun 30, 2009)

It's probably unmetered air getting in to your motor somewhere. Or maybe your injectors are clogged, or your fuel pressure and/or volume isn't up to snuff. Could be any number of things.

What is your injector pulsewidth?


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## X-Ravin (Oct 6, 2010)

I can't remember my IPW's off hand but pressure is fine at idle and doesn't leak down very much. I did the WD-40 vacuum test with no change, but I didn't spray the intake manifold because I wasn't sure where best to spray it. So can just a CAI cause this big of a swing in trims? I wish I had the original intake to do a baseline scan. I just don't want to chase down problems that are just tuning based, or try to tune out problems that aren't.


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## Poncho Dan (Jun 30, 2009)

Yeah an intake shouldn't do that, it has to be unmetered air.


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## X-Ravin (Oct 6, 2010)

Poncho Dan said:


> Yeah an intake shouldn't do that, it has to be unmetered air.


That's the inkling I had, just wanted to get some second opinions. This weekend I'll spray around the engine and see what happens. I think there may be an exhaust leak too. Sometimes I get a puffing noise from under the engine.


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## Poncho Dan (Jun 30, 2009)

If you have an exhaust leak upstream from your O2 sensor, it'll make the car run a bit off. A leak will give it a venturi effect, drawing some outside air into the exhaust stream, causing the sensor to read high O2 levels, which in theory would actually cause the PCM to lean out the mixture a little. Never hurts to check though. :cheers


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## X-Ravin (Oct 6, 2010)

I'll probably have to take it in to have that checked since I'm working in my apartment parking lot  I also may have over-oiled the filter when I cleaned it, so the MAF may be getting hammered with oil. Any way to get excess oil off a K&N cone?


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## svede1212 (Nov 1, 2005)

X-Ravin said:


> I'll probably have to take it in to have that checked since I'm working in my apartment parking lot  I also may have over-oiled the filter when I cleaned it, so the MAF may be getting hammered with oil. Any way to get excess oil off a K&N cone?


Set it in the sun on a bath towel or in an oven that you can warm not too hot for a while. The oil will slowly migrate down and wick onto where the towel touches. _DO NOT_ blow it out with air.


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## X-Ravin (Oct 6, 2010)

Cool thanks! I don't know if I over oiled but it was the first time I've recharged a filter so I'm guessing I probably didn't do it perfectly.


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## svede1212 (Nov 1, 2005)

From what I've seen most people clean it too frequently. Unless you have very dusty conditions you can go 25,000-50,000 miles between cleanings. Just because it looks dirty doesn't mean it needs it. Altho when it real dirty it starts restricting, as it gets a little dirty it filters finer particles. Good luck.

K&N Air Filter Cleaning Instructions


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