killerpenguin21

iTrader: (20)

2006 evo with 54k miles, basic bolt ons, 100% stock fuel system. I have tuned the the timing/fuel, and no extra tables have ever been touched as far as i know. ive done plenty of reading and cant decide how to proceed with this.

i have owned the car for almost two years, and would occasionally get P0215 (or whatever the code is for slow front o2 sensor), but typically only if i let the car idle without moving for a decent amount of time. furthermore, my LTFT cruise trim has been pegged at +12.5 for as long as ive owned the car, but idle trims were about +3-4.

last week i finally got around to putting in a new denso front o2 sensor, and have done about 300 miles of driving since, including a long highway cruise. LTFT cruise is still pegged at +12.5, and now idle trims have crept up to about +9. MAF is plugged in, FPR hose is fine, driveability at low speed and taking off from a stop smoothed out with the new sensor, and overall its running great.

My thoughts:
- I dont think this is an o2 sensor issue
- I'm inclined to think this is not a maf issue, due to the good running

I have a perrin intake which they market as not needing maf scaling, so this points me to either an issue with a maf compensation table, or the scaling of the stock injectors as far as i can tell (both of which are untouched)

unfortunately i dont have a wideband sensor in at the moment since i put in a berk hi flow cat lat week, but after the sensor change all afr's looked good and idle/cruise afr's were a much tighter range around 14.7...but my highway mileage did seem to decrease.

any thoughts would be greatly appreciated.

Anarchy99

iTrader: (196)

You should unplug the ecu to zero out the trims #1 before logging.

The Perrin is an OILED filter afro so its likely coated the inside of your maf with tire-wet-like oils. So it may be cutting down the signal...

Once you have zeroed out the ecu and q-tipped your maf clean, then you will have a better idea where you stand. I have a maf sensor available if you want to buy one to replace it with.

killerpenguin21

iTrader: (20)

yeah i meant to unplug the battery before my road trip ill do it after work tonight...will take me awhile to do enough driving i think though (i live 2 miles from work).

i believe i cleaned the maf with CRC cleaner last summer post perrin install and the cruise trim didnt change, but i was definitely planning on giving it a shot this weekend also.

my concern/confusion is why all of a sudden with a new front o2 the idle trim drifted up.

dastallion951

your ecu is having to add fuel to the LTFT. that means your trims are way on the lean side, you typically wanna have it between 0-3 + or - although it is better to be on the - side because then its a bit rich which is better then a bit lean. Sounds like you need to work on your voltage and scaling for the injectors. Now are you running higher then stock boost?? Stock fuel pump?? those issues could be the reason why when you get up in higher rpms you might be running into an issue.
good luck

killerpenguin21

iTrader: (20)

tune is for 24psi, stock injectors and stock pump. IMHO i dont think i should have to scale stock injectors, but im starting to feel otherwise at this point.

the car is not running lean under power (see below) the lean condition CEL came on under low speed city driving. i live/commute through the city. im 99% sure the ses is being triggered by the bad fuel trims...but i cant figure out why the trims are bad...i had all my money on the o2 sensor.



i disconnected the battery and am in the process of cleaning the maf. the intake tube is dry as a bone, but the filter bracket had oil all over it...i should have cleaned the filter off when the intake was new and ran the filter dry like i had thought about...it was definitely over oiled when new...maybe all the oil has worked its way off now...who knows.

killerpenguin21

iTrader: (20)

i also went over the rom last night. all maf and injector related tables are 100% stock.

killerpenguin21

iTrader: (20)

did about 20 miles on the highway. and a 5 minute idle.

LTFT mid is now +6.8
LTFT low is now +5.8
O2 sensor voltage is nice and active/reactive. much better than the old sensor.

this is better than it was, but i still think something is going on. ill try and do some more highway tomorrow and see if the mid trim goes up anymore. overall the car in all types of driving is buttery smooth.

Anarchy99

iTrader: (196)

Still too high for stock injectors ltft

killerpenguin21

iTrader: (20)

yeah...i realize that.

stroked4g63

iTrader: (2)

Check for a vacuum leak after the maf. The o2s are compensating for the increase of oxygen in the exhaust stream that the maf isn't reading. Example. Vacuum leak, a leak in the intercooler piping or even an intake manifold gasket leak.

Just my two cents. Hope it helps

killerpenguin21

iTrader: (20)

i double checked the FPR line, its there and on tight. i tightened up the UICP couplers more (ets with t bolts). i installed a mil.spec refurbed TB with mil.spec seals last year so i know those are good.

the car pulls 20 in/hg at idle and is hitting and holding my set boost...im very inclined to think there are no leaks...but i wont have access to doing a boost leak until im on vacation again in june.

my only other thought at this time is possibly the injector o rings. ive got fic 1100's and a pump sitting on my bench, but it would suck to install all that and not be able to scale everything.

at least +6 is better than maxxed out, and it should not give me an SES light

killerpenguin21

iTrader: (20)

did about another 40 miles today. cruise trim now seems to be hanging out between +5.8 and +6ish.

i believe the factory spec is actually +/-5%...so i think im in decent shape right now.

killerpenguin21

iTrader: (20)

well im back to ltft low pegged at +12.5 and popping the cel. coincidentally (i think) i was down to about 1/4 tank of gas, filled up, started the car and the light came on.

did 2 logged pulls...boost runs right up to 24psi and holds like it should, car is driving very well.

it sounds like i have a small exhaust leak at one of the joints of my cat, but that should be far enough back to not effect trims.

what the hell could this be besides a vac leak that i cant find?

fireroasted

iTrader: (3)

Having just been through a similar troubleshooting issue, I can't suggest strongly enough a boost leak test. I bought a 25 dollar unit online, got it a couple day slater, and now I don't know how I ever tuned anything or troubleshot any of all those joints before using that. You just don't know what you don't know. Having the car stationary and being able to set the regulator on a compressor and use soapy water is the truth serum of that entire air path.

I can hold 25psi now, and at that point a line off my IM comes off, because I don't have a clamp small enough. BUT, I can hold that 25psi with the stock turbo in a log easy. My point is you don't know about that leak from your logs.

I wasted a bunch of time troubleshooting only to find many little leaks I would have never known about at 25psi.

Even a tiny leak especially under vacuum could cause you scenario. I throw my 2 cents in with stroked4g63.

Good luck!