STFT at -25%?
 

I am thinking it should be a faulty front o2 sensor

CEL is on with code p0410, and what i noticed is that the stft is at -25%, the system had a system run rich code once but never came back, and these sensor usually fails at "omg running rich" state, what u guys think?

Oh btw, air pump works.

I think you need to pay more attention to what LTFT does and pay less attention to stft

Well, everything else seems fairly normal, stft is the only one thats shooting way down. :(

I will double check the ltft in a bit.

hmm, ltft is -3%, seems fine.

Freeze Frame - Mode 2
P0172- (PCM)
(FUELSYS1) : Closed Loop
(FUELSYS2) : ------
(LOAD) : 45.88%
(ECT) : 72�‹C
(SFT1) : -25%
(LFT1) : -3.13%
(RPM) : 850.25RPM
(VS) : 0KPH
(SPARKADV) : 14�‹
(IAT) : 23�‹C
(MAF) : 8g/s
(TP) : 16.08%
(SAIR_COM) : OFF
(RUNTM) : 03:39
(EVAPPCT) : 0%
(FLI) : 57.65%
(WARMUPS) : 3
(CLRDIST) : 28km
(BARO) : 101KPa
(CATTEMP11) : 691�‹C
(VPWR) : 14.06V
(ALV) : 29.8%
(EQ_RAT) : 14.92:1
(TP_REL) : 7.45%
(TP_B) : 32.94%
(APP_D) : 36.08%
(APP_E) : 24.71%
(TAC_PCT) : 8.24%

One more thing I remember is the car has a *looks like never been cleaned* K&N filter, engine can't breathe = Running rich ?

I'm starting to wonder if it has something to do with that, but when I read the Front O2 sensor PID, when accelerate I can see (-) value sometimes, so it seems the sensor is bad cuz according to FSM, I should only see positive when accelerate, and I should only see (-) when decel, correct ?

Also the MAF @ 8g seems a bit abnormal ? I thought the spec was about 5g at idle after warm up ? what you guys think ?

does it happen only when 'cold' (Oil temp<70C)? after engine fully warmed-up everything fine? i'm having something similar but only when Oil temp<70C.

ECT = 72 Celsius

it only triggers when it's in closed loop, which means it's already warmed up.

Im gonna swap the O2 sensor soon to see if it still goes nuts next week.

search n00b!

um 8g/s does seem like a lot at idle. since its got a k&N, i would replace it with a paper filter, and clean the MAF, its probably covered in K&N juice....

i'd do the 02 second, cause its more work :shocking:

our first trouble shooting step with the older Rx7's is to look for aftermarket parts, usually throwing them into the woods would fix the problem...

P0410 could mean the pump is working when not supposed to, which will skew the O2 sensor readings. so i'd start by doing the air pump tests before worrying about fuel trims and O2 sensors.

Im gonna go check his car out again this weekend, will update this later ;)

I did throw his k&n filter away, installed stock filter back, maf readings back to normal but doesnt solve his 25% issue

So i start monitoring all sensors, and the o2 sensor gives f up readings when decel. Replaced, (yea its hell lot more work, since factory sensor is not coated with anti seize ...)

Replaced that as well, everything back to normal.

I knew it was o2 sensor cuz it had a system rich cel once, but it never had any o2 sensor cel. Thats a big hint when its about to gail

I have a turbo buddy who is tuning with Kane who is having the same issue. He has replaced just about all of the sensors, extensive vacuum checks, etc. and done everything else we all can think of. I never thought to ask him how old his ECT sensor was. Hmmm.

ECT sensor ? was it really bad? I mean that sensor rarely rarely fails.

the front O2?
it was 'stuck' at giving -25% STFT no matter hot or cold?

ECU will not take O2 sensor's reading seriously until it's at least 70 ish Celsius on ECT.

STFT moves around a lot, because it depends on several factors, but under normal condition, you should not be able to see anything higher than around 10%, and when you do for a long time, you have a problem somewhere. failed sensor, leak, etc

hmm...:rolleyes:
when my ECT is above 70C, car idles and run fine. below 70C, STFT moves alot as you said and engine couldn't hold idle and stall.

so what sensors affect the idle when below 70C? MAF?

u probably have a leak somewhere. check it.