I have a 1998 Honda accord Ex v6. I Bought the about a year and a half ago and quite a bit of work has gone into the little things due to wear and tear over time. The car has about 215,000 miles on it, and i bought it with 196,000 on it. Since then ive had to put in a rebuilt tranny twice, hopefully this one stays good for awhile. Also, my Cat is gutted because it was clogged up, but dont worry, i will be replacing it when i redo my full exhaust system in a few weeks. Anyways, a problem thats been happening for awhile is a form of surging i would say while driving. When i first turn on the car, the rpms are at about 1750 or so, plus or minus 200, and it stays that way for about 5 minutes and then lowers to about 700. If i try to put the car into drive while the rpms are that high in the 1700's the car sort of takes a little jerk, obviously because the rpms are so high while putting it into gear. As it does this on every startup, i usually have to start my car and wait a little bit before driving so the rpm's go down. However nomatter if i wait to put it into drive or not, when driving at a constant speed, the car often shutters or surges, and the rpms fluctuate up and down and i will sometimes lose speed for a few seconds and it will continuously do this on and off while driving. My MIL status light is on and brings up the code P0171(Bank 1 system too lean). I will include all of the live data from my car at idle with my obd scanner at the end of this post. I noticed that my ST FTRM1% stays at around 45 at idle. Im not sure what the values are supposed to be here. If anyone has any ideas on what could be a fix for the high rpms on startup and my fuel trim readings, and maybe if you notice any other problems with my live data, that would be great thanks!

MIL STATUS: ON
ABSLT TPS %: 9.4
ENG SPEED RPM: 674
CALC LOAD %: 28.6
MAP KPA: 30
COOLANT F: 186 DEGREES
IAT F: 113 DEGREES
IGN ADV DEG: 29.0
ST FTRM1 %: 46.8
LT FTRM %: 18.7
VEH SPEED MPH: 0
FUEL SYS 1: CLSD
FUEL SYS 2: N/A
O2S11 V: 0.035
ST FTRM11 %: 46.8
02S12 V: 1.015
ST FTRM12 %: 0.0
OBD2 STAT: CA

 

High LTFT and STFT suggests an air intake leak (intake manifold, PVC, brake boost, etc). Inspect carefully for an obvious air leak. You can spray w/ throttle body cleaner to look for a change in idle speed to indicate leak location.

Suggest also checking LTFT and STFT at a higher rpm, perhaps 2000 rpm. If LTFT reduces at higher speed, a vacuum leak is very likely. Your idle values suggest a major air leak.

P0171 can be caused by intake air leak, but can also be caused by poor fuel delivery (partially blocked injector, low fuel pressure, blocked fuel filter). First try to confirm that an intake air leak is present.

good luck

 

On OBD-II 5th and 6th generation Accords, P0171 by itself was usually due to the primary O2 sensor.

 

As to TexasHonda, i will definitely first try to check for an air leak. Ive heard around that its definitely a possibility and that i should check it, i just wasnt sure how the best way to confirm it is. Ill test my STFT levels are higher rpms and see how they look. Thanks!
And to redbull-1, thanks, i actually replaced my upstream o2 sensor a few months back so i might look into checking my downstream in the future and see if it could help with my MIL.

 

You need both LTFT and STFT and higher RPM.

A way to test the O2 sensor is to observe a graph of O2 voltage (assuming your tool will do this) w/ engine idling. If O2 sensor is oscillating )from 0.1-0.2 to 0.8-0.9 V, then O2 sensor is likely working correctly. Also forcing a lean (large air leak) to see if voltage goes low (<0.1) and rich condition (throttle body cleaner or propane into intake) voltage goes high (>0.8).

If engine is totally lean (your readings suggest this is case), then you can't simulate a lean condition, but may be able to force a rich condition to confirm O2 sensor performance.

good luck