Running lean - LTFT +18

[K04-B6]

Hello all,

I've been keeping an eye out on my readiness lately and at the same time checking out my fuel trim levels. My long term fuel trim has been staying at roughly +18 and short term seems to stay within it's limit with the odd time of it going +12, from my last posts I had said that my readiness wasn't passing for CAT, 02S and Air. The other night I decided to drop the front bumper and do a soapy water test (I did a boost leak test roughly a month ago with no leaks detected) spray test confirmed that I have no vacuum leaks or intercooler piping leaks, I had done the ''simplification'' but have put everything back into place except the SAI. All vaccum lines have been back in place for about a week and a half.

I decided to play around with my primary 02 sensor wiring and intake manifold, I noticed that my intake manifold wasn't completely tighten down from the time I changed the gasket. I forgot to re-check the bolts after initial install and a bit of driving. Now my intake is properly tighten down and I now have a passing mark for my 02 sensors. I'm only getting a fail for CAT and Air. Air would be because I deleted the SAI and the Cat i'm not sure about. I'm waiting on a 02 spacer to see if this will fix the CAT readiness but I won't know ti'll I install.

I've been checking out my MAF readings and they seem to be fine.. at idle im sitting at 2.50 - 2.75 g's and a second gear pull to redline gave me a maximum of 177g's. I would think this is normal with the upgrades I have listed in my sig. When at idle I have this strange cut off that happens here and there and it gets annoying, I have unplugged my MAF while at idle and it does the same ''cut off'' but then remains a steady idle with the same effects as if it was plugged in. I haven't driven around with the MAF unplugged because I feel that it's in working order with the readings that it's giving me.

I'm completely lost as to what would cause my car to run lean. I had thought maybe that since my intake wasn't properly secure that would cause the issue but it's been properly tighten down for 2 days now and I still have the same readings. everything seems to be in working order and I have no codes nor do I have any pending codes...

Anyone know what I can do next? I only have a shitty version of Vag so sources are limited and I do not have a boost gauge.


Any help is appreciated

[chad99]

I would pick up a vacuum gauge and check your vacuum at idle before moving forward

Also this cutting off your referring to, is that a misfire, does 015 016 pick it up?

[gunde]

Is the lean condition a new problem or did you just installed the k04 with the apr programming?
My engine ran lean between 20 and 25 on the fuel trim, with the occasional chech engine when the trim reach 25. I ,like you,have a 2002.

[K04-B6]

I would pick up a vacuum gauge and check your vacuum at idle before moving forward

Also this cutting off your referring to, is that a misfire, does 015 016 pick it up?

No it's not a misfire but it almost feels like one. If I had a misfire it would happen more often and I eventually would get a CEL. It might be my fuel injector harness, I took a closer look and noticed the wires didn't look to great but are still intact. I wonder if that would cause this issue. There's a lot of possibilities which really sucks! I feel like its just a matter of time before this really damages my motor.

Is the lean condition a new problem or did you just installed the k04 with the apr programming?
My engine ran lean between 20 and 25 on the fuel trim, with the occasional chech engine when the trim reach 25. I ,like you,have a 2002.

This is a new problem. The K04 and APR software were already installed when I purchased the car so it's roughly 4 years since its in the car. I used to get a lean code when I first got the car from time to time but ever since I've upgraded to a front mount and changed all my plumbing I haven't had a CEL. I wonder how long I've been running lean for?? APR never returns my emails and when I call I get shitty service. Im almost to the point to where I think maybe I should just get a new tune!

I received my 02 sensor spacers today in the mail, one is a 90 degree elbow and the other piece is a straight piece which I could either have on the 90 or separate. I might try to space both my rear and front 02 sensors and see if it helps with readings since my tune possibly isn't programmed for HFC and downpipe.

[gunde]

Don't put the spacer on the front O2 sensor. The ecu needs the proper/real reading to adjust a/f ratio.
On my car, I replaced and checked every possibilities to correct the lean code, without help from apr. I fixed the issue by switching to Unitronic...

[K04-B6]

Don't put the spacer on the front O2 sensor. The ecu needs the proper/real reading to adjust a/f ratio.
On my car, I replaced and checked every possibilities to correct the lean code, without help from apr. I fixed the issue by switching to Unitronic...

You're right, I've been doing a lot of reading this morning and I won't space out the front sensor. My 02 readiness has gone back to fail so i'm wondering if the front 02 is going bad and causing this. I will install the spacer on the rear 02 tonight and hopefully that will help me pass on my CAT readiness.

I might end up doing like yourself and switching tunes eventually if this keeps up. I've done boost leak tests, soapy water test with no leaks so it's either MAF or 02 that's left. My MAF readings are normal from what i've been searching so im leaning towards the 02 sensor but i'll wait to get a proper scanner to test it out before wasting money on a sensor.

What upgrades are you running?

[gunde]

I have er sport fmic, unitronic k04 93 tune, neuspeed turbo inlet pipe, unitronic 3'' downpipe

[K04-B6]

Do you still have the stock cat in place or do you have the HFC/DP combo like I do?

I'm not sure if you would know this information but: Is it the rear 02 that sets the CAT readiness and is it the front 02 that sets the 02S readiness?

[gunde]

Do you still have the stock cat in place or do you have the HFC/DP combo like I do?

I'm not sure if you would know this information but: Is it the rear 02 that sets the CAT readiness and is it the front 02 that sets the 02S readiness?

I do have the cat /dp combo. I was able to get rid of the cel with a spacer, but I removed it and run with the cel now. Neither APR or Uni have cat delete files for my model number.

[K04-B6]

I do have the cat /dp combo. I was able to get rid of the cel with a spacer, but I removed it and run with the cel now. Neither APR or Uni have cat delete files for my model number.

This is what I find odd as well, I haven't installed a spacer yet and never got a CEL. The only reason I want to install a spacer is to set readiness for my CAT and 02S so I can go for my damn etest.

[K04-B6]

Well the spacer didn't do shit. still not passing readiness for CAT and 02S. I think it might be the tune falling apart. I might be posting a part out in the next couples of months. Sick of this car lol