Hmm...fuel trims

I was looking over some data I had logged today and for a comparison, I took a look at data logged over the past 6 months or so - since before I started modifying anything. The most interesting thing I've noticed that I want to get to the bottom to is my fuel trim.

To be brief, before I removed my Non-PI intake for the first time, my fuel trims were generally between -5% to 1%, indicating it was mostly leaning out the mixture. But when I reinstalled that same Non-PI intake after a failed attempt to get my PI intake on, the fuel trims have been around 9-15% at idle and around 5-7% at highway cruising speed (what used to be in the negatives).

Here are the logged long term fuel trim tables:
Before (http://richgannon.info/gallery/displayimage.php?pos=-437)
After (http://richgannon.info/gallery/displayimage.php?pos=-436)

Both were on the same highway route with similar conditions a single week apart from each other.
Estimated fuel mileages were pretty much the same. The before values were consistent for the past few months. The after values have been consistent since.

What could cause this? A vacuum leak? It is NOT related to my tune as this apparently began before I ever ordered it. I have since removed the NPI intake and installed my PI intake, and still has the same general fuel trim.

By the way, this change has happened on BOTH banks according to my logs.

I am not fimiliar with how Ford/Mercury program their motors. But, I have spent a significant amount of time playing with my LS1 motor. I know the PCM is always trying to achieve 14.7 to 1 air fuel ratio. GM sets the parameters for LTFT's to -5% to +5%.

The STFT's make up the average for LTFT and if over time if LTFT's are outside the (+%) or (-%) parameters you'll get a code. On LS1 motors you do not have to pay attention to idle trims. One should monitor the LTFT's a constant MPH to determine if they are set when the range of the manufacturer after allowing the PCM to adjust to new settings.

What software are you using - looks pretty sophisticated. Similiar to LS1 edit for GM.

I would think you have a vacuum leak somewhere somewhere based on the values
I know I have vacuum leak on my LS1 because I'm getting a lean code and I'm adding fuel...

The mmods I've done to my GTO are a CAI, breather filter which really improved pedal response and an oil catch can to filter the contents coming out of the valley post combustion...

This has required me to add a significant amount of fuel to keep LTFT's within the specied parameters.

Hey Blue. Where is the rest of the data? There is no engine temp, coolant temp, air temp, STFT and others. Need to look at all of them to figure it out. If it has gone positive, look to a bad fuel regulator. Ford says 12%+ to 12%- are normal readings. I do not agree, but that is their specs.

Hey guys, I noticed that when I add new pictures to the album my links showed different pictures so I just fixed that incase you mistakenly saw some pictures other than what I had posted.

The software I use for logging in the images is ScanXL used with an ELM Scan5 device.

Anyway since this was two months ago I pretty much ruled out any vacuum leaks. I am thinking it's just lazy O2 sensors. They are original and I'm only about 150 miles shy of 100k as of today. I don't want to do much more tinkering or jumping to assumptions until I get the chance to replace them. It may take me a while to get to it but when I change them I'll let you guys know if it solved the problem or not.

By the way, both photos were when the IAT was ranging between 75 and 80F and my ECT and CHT run steady at 190. And both were logged over the duration of the same 2-hour trip on the same highway and always use cruise control at 70-72MPH running in the 1700-1750RPM area. STFT is very near 0 under all of the logs I have taken since then.