2010 XK 55k miles, maintained by me personally.

Requesting help from the tuning experts we have in the forum!!
Ive cleaned my intake valves using CRC intake cleaner and have noticed some
performance improvement while driving. I have also inspected for vacuum leaks
and replaced the intake tubing that goes into the throttle body.

Here are my latest fuel trims, could someone chime in on what this means?
I dont understand the black boxes or what are acceptable ranges

Thanks!

 

All I can tell you is that my Long Term Fuel Trims are all at very-near zero, if not zero.
My SHORT Term Trims fluctuate a little bit, but not very much.

 

Too lean at all load regions.
-Huge air leaks pre or past-throttle
-Faulty MAF(s)
-Faulty cat(s)/upstream O2S(s)

 

Moscowleaper, thanks for your reply
I have read many of your informative posts!

How long does it take for LTFT to update?
1 day, 1 week, or 500 miles, for example,

Should I be driving when I run the LTFT in SDD?
I ran the LTFT service with the engine off, does this matter?

 

I would check for leaks. Try using a smoke machine , can diagnose pretty accurately...
You can resett fuel trims by disconnecting the battery or your SDD tool

 

Basically as soon as coolant reaches 80degC it takes less than a minute to update a LTFT if there's a reason for that (STFT should be higher/lower than 0 for a 2-3%)

 

From from my experience it takes a lot longer then a minute. I would say more like half an hour to few hours of driving

 

Bear in mind if the STFT is large the PCM moves the LTFT a bit and then repeats, so if there's quite a leak the STFT will again be out and this cycle will go on for quite a while until either the STFT is OK or a code flags.

 

I haven't found the leak yet, still looking..

I did install new air filters not that long ago, is it possible that poor fitting
air filters could cause such a lean condition?

 

Yes, as well as if the box isn't seated properly.

 

Reseated airfilters, my LTFT did change but not as expected
it evened out the banks, but still running +7 to +9
no vacuum leaks found yet,

I forgot to mention, my car has an X-pipe and muffler delete
It was my understanding that these alone would not cause
a fuel mixture change correct?

 

A good way to reset your LTFTs is to do a Hard Reset. Then drive for awhile and see what happens then.
I had to do that when I popped one injector..... the LTFTs and the STFTs both took a pooh. I reset, drove, and then all was perfect.

 

Thanks Cee Jay, this was helpful! However after resetting
and driving a bit I'm still running lean (ecu adding fuel)
Need a proper smoke machine to test,

 

I suspect my X-Pipe and Mufflet delete is affecting my
fuel trims due to decreased back pressure and or scavenging,

This is why I wanted to get a tune in then first place
To help adapt for my exhaust setup.

 

The x-pipe and muffler won't affect fuel trims THAT much.

 

unlikely.

you have an air leak pre cat so get the smoke tested and find it. With all the o rings and seals its easy to leak. My car had several and the smoke tester found them all.

 

Solved the problem, it was due to my air filters not seating properly in the air box,
and a crack in the air ducting Y that leads into the throttle body.
Here are my current LTFTs pretty close to normal now.

Its also important to note that SDD takes forever to update LTFT values,
not sure if its x amount of miles or drive cycles.
I found the best way to read the LTFT is with live data via bluetooth obd2 device.

 

I’ve been watching this thread. I’m glad to see that you got this resolved!