Long Term Fuel Trim 24.2 at idle!!
06-01-2015, 05:13 PM
#1
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Long Term Fuel Trim 24.2 at idle!! Hey guys trying to chase down an issue here. Sometimes the car starts first try and sometimes it takes 7-10 times. It doesnt matter if it is hot or cold summer or winter. I have replaced the Ign relay, TPS sensor, o2 sensors etc etc. Car has a frost tune on it longtubes full 3" exhaust. Ls6 intake. Here are the readings that i got on freeze frame at idle.
MAP (inHG) 10.9
ENG RPM 1127
Veh Spd 0
MAF (lbs/min) 0.306
TPS (%) 0.3
ETC (Degrees F) 127
STFT B1% -0.7
LTFT B1% 24.2
STFT B2% -0.7
LTFT B2% 23.4
Any help or advice would be much apperciated!!
MAP (inHG) 10.9
ENG RPM 1127
Veh Spd 0
MAF (lbs/min) 0.306
TPS (%) 0.3
ETC (Degrees F) 127
STFT B1% -0.7
LTFT B1% 24.2
STFT B2% -0.7
LTFT B2% 23.4
Any help or advice would be much apperciated!!
06-02-2015, 09:49 PM
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I unplugged the MAF and the car runs the exact same without it, which is odd to me. I will go tomorrow and buy a new PCV and a can of carb cleaner and spray for a possible vaccum leak. The eng sen fuse looked good but I replaced it anyway and no change. Thank you guys for your responses I have been fighting this for 3 months testing and trying everything
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06-02-2015, 10:49 PM
#8
You don't need a new PCV Valve. The hose between it and the intake manifolds rots over time and leaks. Just check the short piece of hose. That is if it is a 99-02 f-body. It would help to know the year and type of car. Why do people repeatedly omit this basic information.
06-03-2015, 02:15 PM
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With long tubes you can't rule out that the high LTFTs
are from false trimming, cold O2 sensors.
What to look at is, high-idle it for a bit to get things hot
and watch STFTs and LTFTs. See if they begin to recede
(less positive, or negative STFTs pulling back LTFTs
slowly) on a return to idle, but then heading back to a
positive creep after time-at-idle has cooled the pipes.
This is your false trimming from heat issues signature.
ECT at 127F is abnormally low for warmed-up and the
picture might change when ECT has settled in (but
also may change with the weather and its thermal
contribution to sensor cooling).
are from false trimming, cold O2 sensors.
What to look at is, high-idle it for a bit to get things hot
and watch STFTs and LTFTs. See if they begin to recede
(less positive, or negative STFTs pulling back LTFTs
slowly) on a return to idle, but then heading back to a
positive creep after time-at-idle has cooled the pipes.
This is your false trimming from heat issues signature.
ECT at 127F is abnormally low for warmed-up and the
picture might change when ECT has settled in (but
also may change with the weather and its thermal
contribution to sensor cooling).
06-03-2015, 05:55 PM
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I removed both the pcv line that runs to the throttle body and passenger valve cover and also the other vent line that runs from the throttle body back behind the valve cover on the drivers side. I carefully inspected both lines numerous times and there are no cracks or splits in them.
06-04-2015, 01:28 PM
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The car does not have any Evap system on it, supposedly it's all tuned out via frost. The line that runs to the PCV from the throttle body on the passenger side is the only vaccum line on that side of the motor from what I seen yesterday. After work I will look again how long is the hose? A couple of inches??
06-04-2015, 04:40 PM
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Figured out the P0102 code. I seen a little bit of electrical tape around the wire loom going to the mass airflow sensor so being curious I ripped it all apart and sure enough the red wire was cut in 2. Could the MAF not functioning properly make the car run extremely rich and also cause the hard starting issues?
06-04-2015, 05:48 PM
#18
Figured out the P0102 code. I seen a little bit of electrical tape around the wire loom going to the mass airflow sensor so being curious I ripped it all apart and sure enough the red wire was cut in 2. Could the MAF not functioning properly make the car run extremely rich and also cause the hard starting issues?
When you repair it disconnect the battery for a while to drain the KAM. Start it and let it idle for a few minutes so it will start learning again and see what the STFT/LTFT are. 
