[SOLVED] 2000 camry gen4 5sfe short and long term fuel trims

[fenixus]

hello happy people,

i wonder how many of you likes to play with OBD2 software on laptop connected to a running car. since i already started doing it i have a question.

how do your fuel trims looks alike at idle and when driving?

STFT - short term fuel trim
LTFT - long term fuel trim

mine are hilarious (no CELs though):

1) after 5 months from tune up, oil change and TB/IAC cleaning

at idle (closed loop)
STFT -1.6%
LTFT +14.8%
RPM ~990

when cruising 66mph T[552PM]
STFT -2.34
LTFT +1.56
RPM ~2400

2) after adding 12oz of Chevron Techron to 1/3 tank and driving a little on highway (includes 6k rpm acceleration)

at idle (closed loop)
STFT -0.78%
LTFT +20.3% !!!
RPM 988

when cruising 30mph (after highway driving)
STFT +7.81%
LTFT +1.56%

OR

T[711PM]
VSS 31MPH
STFT -14.84%
LTFT +20.31%
RPM 1128
MAP 3.63psi

when cruising 60mph

T[709PM]
VSS 61MPH
STFT +3.91%
LTFT -0.78%
RPM 2252
MAP 4.35psi

It's said that its best to keep those numbers in +/-5% bracket ... well mine seem way off. LTFT gets crazy high at idle while during highway driving it almost zeroes out. can anybody shed some more light on this ?

just trying to figure it out if fuel injectors are bad (in what way exactly) or I have air/vacuum leak or so.

thanks.

[hill8570]

Have you intentionally dinked with your idle speed? My first guess it that if you figure out why your idle is so riduculously high (spec is 750 +/- 50), you'll have a good handle on why your LTFT is so high. Something is causing the first-order fuel charge calculation to be too lean at idle, and the ECU is having to tweek it up based on the A/F sensor readings.

Any chance you've got a small leak on your intake manifold gasket? The MAP sensor tends to adjust for pretty much any other extra air coming in from a leak.

[fenixus]

hmmm, i thought idle revs close to 1,000 are normal in Park or Neutral. they drop to 650-750 when i shift it to any driving gear. correct me if wrong, this would explain a lot.

i haven't adjusted anything to be like this. its always been like that or a little lower when IAC gets dirty...

i start suspecting the oxygen sensor. is this the one sitting in the exhaust something in front of engine (wire sticks out from there) ?

when driving those trims are good and usually within +/-5%. it's only they get MUCH worse at idle when sensor controls them (close loop).

it's possible i have air/vacuum leak. cannot be big though as i cannot hear any hissing sounds under hood. the only confirmed leak is oil from valve cover and possibly a PCV grommet is not sitting tight (old one).

if you have any other thoughts pls post, i'm learning this stuff. i will try looking up a reading when car was at full stop in gear (rpm ~700) to see what the trims were. 1 sec.

Here you go, trims are same as they were, engine revs are ~700, car was sitting in parking lot shifted to D (or R) gear.

02/27/2010 04:06pm
STFT +1.59%
LTFT +17.19%
RPM 708
VSS 0mph
MAP 5.08psi

this is whole raw data for this reading, i think i got here also the voltage of oxygen sensor controlling close loop (O2S12 = O2 Sensor Bank 1 - Sensor 2 Voltage):

"LOAD_PCT", 33.72549, False, 2/27/2010 4:06:26 PM
"ECT", 208.4, False, 2/27/2010 4:06:27 PM
"SHRTFT1", 1.5625, False, 2/27/2010 4:06:27 PM
"LONGFT1", 17.1875, False, 2/27/2010 4:06:27 PM
"MAP", 5.076321, False, 2/27/2010 4:06:27 PM
"RPM", 708.75, False, 2/27/2010 4:06:28 PM
"VSS", 0, False, 2/27/2010 4:06:28 PM
"SPARKADV", 7.5, False, 2/27/2010 4:06:28 PM
"IAT", 75.2, False, 2/27/2010 4:06:28 PM
"TP", 13.72549, False, 2/27/2010 4:06:29 PM
"O2S12", 0.725, False, 2/27/2010 4:06:29 PM
"SHRTFT12", 0, False, 2/27/2010 4:06:29 PM
"EQ_RAT11", 1.000095, False, 2/27/2010 4:06:29 PM
"OS211", 3.294, False, 2/27/2010 4:06:29 PM

that sensor was reading 0.725V, not sure if this is the one. i think it is something else... on the other had in most instances it shows a low voltage of 0.1V at idle meaning it thinks its getting too much air (running too lean) and adjusting ECU to get more fuel...

later will post more full readings. now going to check air filter for leaves and dirt.

can you define a closed loop ? is this whenever i do not press gas pedal or only at idle ? i noticed when cruising at steady speeds (no matter how fast) the fuel trims get crazy high (long term up to 20%)... this confirms this car burns more fuel than in past, i'd like to know why.

and that intake manifold gasket, would it leak oil if something not tight over there ? because i believe some oil from above (valve cover) was leaking down onto intake manifold. perhaps i'm wrong, maybe that's the manifold leaking itself.
does Manifold Absolute Pressure reading help in checking if there is a leak ? can post too.

[hill8570]

Originally Posted by fenixus

hmmm, i thought idle revs close to 1,000 are normal in Park or Neutral. they drop to 650-750 when i shift it to any driving gear. correct me if wrong, this would explain a lot.

Spec for idle (tranny in P or N, A/C off, all accessories off is 700 +/- 50). Horses mouth from the Gen4 FSM, page DI-14.

[fenixus]

dang, you are right hill8570.

it's supposed to be 700+/-50 in Park/Neutral

i could sworn i saw bunch of other 5sfe owners with similar idling speed (P,N) and lower in D.R etc. so i thought it's normal. how do i get it back to 700 while it usually sits at 800-1,000 ?

what's your engine rpm when you shift it to D or R ? mine is around 700+/-50 when i do that. don't know why in Park it's such high ten ...

[fenixus]

i remember i was messing around with lock nuts on accelerator cable, perhaps it's a little too tight. my haynes is not very specific about checking if this cable is within specs.

do you know where i can find this info (accelerator cable adjustment) in camry factory manuals ? thanks.

i need to check this adjustment to make sure its not fooling the ECU and all test results.

[hill8570]

Originally Posted by fenixus

i remember i was messing around with lock nuts on accelerator cable, perhaps it's a little too tight. my haynes is not very specific about checking if this cable is within specs.

do you know where i can find this info (accelerator cable adjustment) in camry factory manuals ? thanks.

i need to check this adjustment to make sure its not fooling the ECU and all test results.

Cable has to be loose enough that the throttle return spring can completely close the throttle when you let off the accelerator pedal. Other than that, no particular spec. A smidge loose is better than too tight. If you idle in "D" at the correct speed, I'd think your cable is OK. My current rig is only a Gen3, but idle in D and idle in P or N is almost the same (P / N might be 50 rpm or so higher than D, but not much).

[hill8570]

Originally Posted by fenixus

how do i get it back to 700 while it usually sits at 800-1,000 ?

I'd probably start by inspecting the throttle opener and throttle position switch (see www.camrystuff.com, Generation 4, Sequential Fuel Injection, starting at page 29), paying close attention to the vacuum / no vacuum on ports E, P, and R on the throttle body. I know from past experience that idle speed goes pretty wonky if the throttle opener does / does not get vacuum at the right times.

[fenixus]

ok thanks, will read that in a sec.

one question though, i see that california vs non-california spec camry have different oxygen sensors. are all north american made camry (or solara in my case) California spec ? even if built in Canada ?

[JohnGD]

Regarding fuel trims, you need to wait for the ST to stabilize and zero out (or close to it) before reading the LT value.

[hill8570]

Originally Posted by fenixus

are all north american made camry (or solara in my case) California spec ? even if built in Canada ?

Pretty sure not, but other states besides California mandated that cars sold in their borders meet Cali specs, so it's kind of a dice roll. Check the emissions sticker on your rig -- either under the hood or on the driver's firewall (never can remember on the Gen4). Should say FEDERAL or CALIFORNIA emissions.

[fenixus]

Originally Posted by hill8570

Pretty sure not, but other states besides California mandated that cars sold in their borders meet Cali specs, so it's kind of a dice roll. Check the emissions sticker on your rig -- either under the hood or on the driver's firewall (never can remember on the Gen4). Should say FEDERAL or CALIFORNIA emissions.

so wait, it means that people from California when buying toyota cars from different states must make sure they comply with California emissions or they need to convert them ?

will try to find that sticker. does OBD2 read such info from ECU ? mine said on 1 occasion that it meets California something, didn't pay attention to that. or will have to compare the differences between cali vs non-cali parts like 3 vs 4 bolts on IAC and additional air assist tube going to TB. will look at it later on.

[JohnGD]

Yes. It's fairly strict in come cases it's impossible. However, there are plenty of out-of-state cars running around. And with the economy in the sewers, the state is thinking about finding ways to deal with these registration fee evaders......ummm I mean polluters.

Of course more and more manufacturers are actually building cars to meet the Calif emissions requirements for sale in all of US. Which I think is a good thing. It's easier to do for luxury car makers like Porsche and BMW than mainstream Model T makers.

I think at least at present time California emissions is still the most stringent in the world. I posted some tables Googled before but don't remember the details at the moment, IIRC when Euro-V comes into play they'll only approximate Calif emissions or some sort.

Originally Posted by fenixus

so wait, it means that people from California when buying toyota cars from different states must make sure they comply with California emissions or they need to convert them ?

will try to find that sticker. does OBD2 read such info from ECU ? mine said on 1 occasion that it meets California something, didn't pay attention to that. or will have to compare the differences between cali vs non-cali parts like 3 vs 4 bolts on IAC and additional air assist tube going to TB. will look at it later on.

[fenixus]

thanks for info.

i couldn't find the sticker about emissions anywhere in engine bay or cabin, door step etc. i looked at the TB and couldn't find the 3rd hose (air assist), all i saw were 2 water bypass hoses which is normal to federal specs. i didn't bother counting IAC bolts, it got too dark.

also i poured another 12oz chevron techron to 1/4 tank (with one 12oz bottle in it already). i know it makes the dose multiple of what directions say, but i was about to fill up the tank (each bottle treats up to 12 gallons only) anyways.

did some tortures on the way to shell station like liberally using L and 2 gears up to rev limiter and than driving with overdrive off. filled up the tank with premium fuel. then took it to highway and revved the hell out of it again a couple times (mostly on highway entrance ramps where they join in).

LTFT stayed dropped a bit to 12.5% after that. having some time for T and me also religiously checked alternator belt tension and surprise, it was down to 100 lbs (i also started hearing "bearing noise" at 2300 rpm yesterday). adjusted it back up to 120lbs and noise is gone completely. weird a bit but i don't complain (lets me know when belt gets loose).
also at this point i have to admit that i misidentified (until today) the alternator pivot bolt and so far was loosening the dog bone mounting arm bolt
corrected myself today and properly adjusted the belt. hopefully it holds the tension now.

running out of ideas i re-adjusted the accelerator cable to something that looked like factory setting - i could say that by dirt on screw. i think now it is exactly where it was a year ago.

after starting the car idle (park) engine speed was ~800 which is close to idle speed on driving gears (100 rpm difference still).

then i noticed a couple things which seem odd, so need confirmation if that is normal.

1) depressing and releasing the brake pedal almost fully a few times causes engine speed to increase by up to 100 rpms when releasing the brake pedal. normal or not ? possible vacuum leak ?

2) after driving a while and setting gear to park idle engine speed is almost always 1000rpm at this point. on cold start and then after warm up it settles almost correctly. then it never comes back to that setting. normal or rather dirty IAC or something ?

as the last resort pulled the EFI fuse and smoked a cigarette. after putting it back in fuel trims were both zeroed out at idle, but in a minute ECU started adjustments giving as high as +14% to short trim at some point. after a while the long trim settled at +11.7% and stayed there even after another torture, idle and another torture.

i notice that when fuel loop opens both trims usually come down to -5%,+5% bracket, but whenever i take my foot off the gas pedal, either when cruising at a steady speed or when idling in parking lot, the fuel loop closes and long trim comes back to 11.7%. does it point toward still dirty injectors or maybe something else (air leak maybe?) ?

what do you think guys ? does it all sound similar to any of you ?

sorry for the lengthy post, tried to write about everything that might be relevant in any kind of diagnosis or further troubleshooting. all i want to achieve is to see LTFT below 5% at idle and regain the superb gas mileage of this ride.

[fenixus]

ahh, forgot to write why i fussed about california vs non-california sensors. every OBD2 software detects ECU in my car as "California II - ARB" and yet i do not see any indication of having California specs by looking at my car. perhaps just a stupid ECU identifier that misleads me (as well as O2 sensor 1 bank 1 voltage which doesn't fit anything at all).

example of current trims and other stuff (engine hot after racing, now idling in Park for a longer while):

02/28/2010 6:31:17PM
Calculated Load 26.7%
Engine Coolant Temp 205F
STFT +0.78%
LTFT +11.72%
MAP 3.77psi
RPM 990
VSS 0mph
Spark Advance 10.5 degrees
Intake Air Temp 64.4F
Absolute Throttle Position 13.7%
O2 bank 1 sensor2 0.62V
o2s12 short fuel trim 0%
o2s11 equivalence ratio 1.01 lambda
O2 bank 1 sensor1 3.31V

and then a few seconds later:

02/28/2010 6:31:36PM
Calculated Load 26.27%
Engine Coolant Temp 208.4F
STFT +2.34%
LTFT +11.72%
MAP 3.77psi
RPM 990
VSS 0mph
Spark Advance 10.5 degrees
Intake Air Temp 66.2F
Absolute Throttle Position 13.7%
O2 bank 1 sensor2 0.20V
o2s12 short fuel trim 0%
o2s11 equivalence ratio 1.00 lambda
O2 bank 1 sensor1 3.30V

and one that makes me think of replacing the oxygen sensors (see voltages), car at idle in D gear, also MAP seems higher than in most idling:

02/28/2010 6:08:55PM
Calculated Load 35.69%
Engine Coolant Temp 203F
STFT +0.78%
LTFT +11.72%
MAP 5.37psi
RPM 701
VSS 0mph
Spark Advance 11 degrees
Intake Air Temp 55.4F
Absolute Throttle Position 13.7%
O2 bank 1 sensor2 0.02V
o2s12 short fuel trim 0%
o2s11 equivalence ratio 0.91 lambda
O2 bank 1 sensor1 2.92V