deadbeatrec

iTrader: (9)

so i just recently posted a thread about finding the solution to my P0171 code....

https://www.evolutionm.net/forums/sh...d.php?t=337499

but that lasted for 2 days and cost me a ticket (testing the boost and got an exhaust ticket)

so the god damn (excuse my french) code is back and i dont know what the F to do. so what i need is a checklist of all and every thing i need to check. im 120% sure i checked everything there is to check and in fact more, but either im missing something or my ECU is just ****ed up.

i was thinking this too, is there anyway the ECU will lose parameters over time? its like at idle the car just cant figure out what to do and the fuel trims are messed up or something. when u first start it, it will go to like 16.5-18 air fuel. then blip the throttle and it will correct itself somewhat and go to 14.5-15.5. this is when the SES light is on mind u.

over the weekend the code was not on and the air fuels were perfect and the ECU seemed to find the correct trims faster and by itself. and open loop is perfect.

i dont get it, and im so fed up with this damn code.

deadbeatrec

iTrader: (9)

everyone is so concerned with dyno numbers and what HTA is coming out next, no one cares about the real issues anymore. thanks guys

caLi4G63

iTrader: (40)

seems like you replaced the seals in the throttle body shaft; if so, have you checked to see that your TPS parameters are within spec? The ECU uses the TPS along with other sensors to help determine what load the engine is under. Worth a shot since you might have or did replace the seals on your TB.

cheb evo

+1, this really sounds like an issue with the TPS. Did you mark the previous location before you took the throttle body apart to replace the seals? May be a dumb question, but could certainly cause the issues you are currently having.

deadbeatrec

iTrader: (9)

yes i marked it and put it right back in the same spot it was.

would this be a different code? and how do i check to see if they are in spec?

gsrboi80

iTrader: (38)

Check the injectors? These could very well be the issue for a poor/searching idle. It would also clearly cause the P0171 code. Maybe one is a bit clogged and not fueling correctly.

1rst check the resistance across each injector. I dont have the manual in front of me but its in there. I can check when I get to work tonight if you still need the value.

2nd Swap out the injectors with anothe set Im sure a local would let you use theirs as a troubleshooting aid.

Are you on stock injectors? If not what does your scaling and latency look like?


Ive seen this in reverse many time in Honda Land. Were a leaky injector would trip a CEL for a Too Rich Condition

Worth a check. As far as the TPS my guess is the IAC would bo more likely to have the P0171 associated to it.

deadbeatrec

iTrader: (9)

ok i have no manual, the injectors are 780 and have only been in there less than 2 years, i do in fact know that the latency is fine as was checked twice by AL (dynoflash) and how can i check the resistance? just unhook the injector and use a ohm meter? also when i got my drop-in pistons and what not they replaced the injector seals too.

deadbeatrec

iTrader: (9)

more i found




AllData description: (if any of this helps, let me know and I can try and get you the pictures associated with this. Most of the pictures just show a scan tool being plugged in, but there's an occasional wiring pinout, etc.)

DTC P0171: System too Lean

System too Lean Circuit


Refer to, DTC P0201 - P0204 Injector Circuit Malfunction.
CIRCUIT OPERATION


Refer to, DTC P0201 - P0204 Injector Circuit Malfunction.
TECHNICAL DESCRIPTION


If a malfunction occurs in the fuel system, the fuel trim value becomes too large.
The ECM or PCM checks whether the fuel trim value is within a specified range.
DTC SET CONDITIONS

Check Conditions


Engine coolant temperature is lower than approximately 100 °C (212 °F) when the engine is started.
Intake air temperature is lower than 60 °C (140 °F) when the engine is started.
Under the closed loop air/fuel ratio control.
Engine coolant temperature is higher than 77 °C (171 °F) .
Volume air flow sensor output frequency is 81 Hz or more.
Judgment Criteria


Long-term fuel trim has continued to be higher than +12.5 percent for 5 seconds . or
Short-term fuel trim has continued to be higher than +10.0 percent for 5 seconds .
Check Conditions


Engine coolant temperature is lower than approximately 100 °C (212 °F) when the engine is started.
Intake air temperature is lower than 60 °C (140 °F) when the engine is started.
Under the closed loop air/fuel ratio control.
Engine coolant temperature is higher than 77 °C (171 °F) .
Volume air flow sensor output frequency is 81 Hz or less.
Judgment Criteria


Long-term fuel trim has continued to be higher than +12.5 percent for 5 seconds . or
Short-term fuel trim has continued to be higher than +15 percent for 5 seconds .
Check Conditions


Engine coolant temperature is higher than approximately 100 °C (212 °F) when the engine is started.
Intake air temperature is higher than 60 °C (140 °F) when the engine is started.
Under the closed loop air/fuel ratio control.
Engine coolant temperature is higher than 77 °C (171 °F) .
Volume air flow sensor output frequency is 81 Hz or more.
Judgment Criteria


Long-term fuel trim has continued to be higher than +12.5 percent for 5 seconds . or
Short-term fuel trim has continued to be higher than +20.0 percent for 5 seconds .
Check Conditions


Engine coolant temperature is higher than approximately 100 °C (212 °F) when the engine is started.
Intake air temperature is higher than 60 °C (140 °F) when the engine is started.
Under the closed loop air/fuel ratio control.
Engine coolant temperature is higher than 77 °C (171 °F) .
Volume air flow sensor output frequency is 81 Hz or less.
Judgment Criteria


Long-term fuel trim has continued to be higher than +12.5 percent for 5 seconds . or
Short-term fuel trim has continued to be higher than +25.0 percent for 5 seconds .
Check Conditions


Engine coolant temperature is higher than 77 °C (171 °F) .
Under the closed loop air/fuel ratio control.
Judgment Criteria


Long-term fuel trim has continued to be +12.5 percent for 5 seconds . or
Short-term fuel trim has continued to be +25.0 percent for 5 seconds .
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are


Volume air flow sensor failed.
Injector failed.
Incorrect fuel pressure.
Air drawn in from gaps in gasket, seals, etc.
Heated oxygen sensor failed.
Engine coolant temperature sensor failed.
Intake air temperature sensor failed.
Barometric pressure sensor failed.
Use of incorrect or contaminated fuel.
ECU failed.
PCM failed.
DIAGNOSIS

Required Special Tool:


MB991502: Scan Tool (MUT-II)
STEP 1. Check for exhaust leaks.

Q: Are there any abnormalities?

YES: Go to Step 2.

NO: Repair it. Then go to Step 14.

STEP 2. Check for intake system vacuum leaks.

Q: Are there any abnormalities?

YES: Go to Step 3.

NO: Repair it. Then go to Step 14.






STEP 3. Using scan tool MB991502, check data list item 12: Volume Air Flow Sensor.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.



Connect scan tool MB991502 to the data link connector.
Start the engine and run at idle.
Set scan tool MB991502 to the data reading mode for item 12, Volume Air Flow Sensor.
Warm up the engine to normal operating temperature: 80 °C to 95 °C (176 °F to 203 °F) .
When idling, between 20 and 46 Hz (between 1.3 and 3.3 gm/s ).
When 2,500 r/min , between 70 and 110 Hz (between 6.6 and 10.2 gm/s ).
Turn the ignition switch to the "LOCK" (OFF) position. Q: Is the sensor operating properly? YES : Go to Step 4. NO : Refer to, DTC P0101 - Volume Air Flow Circuit Range/Performance Problem, DTC P0102 - Volume Air Flow Circuit Low Input.





STEP 4. Using scan tool MB991502, check data list item 13: Intake Air Temperature Sensor.


Turn the ignition switch to the "ON" position.
Set scan tool MB991502 to the data reading mode for item 13, Intake Air Temperature Sensor.
The intake air temperature and temperature shown with the scan tool should approximately match.
Turn the ignition switch to the "LOCK" (OFF) position. Q: Is the sensor operating properly? YES : Go to Step 5. NO : Refer to, DTC P0111 - Intake Air Temperature Circuit Range/Performance Problem, DTC P0112 - Intake Air Temperature Circuit Low Input, DTC P0113- Intake Air Temperature Circuit High input.





STEP 5. Using scan tool MB991502, check data list item 21: Engine Coolant Temperature Sensor.


Turn the ignition switch to the "ON" position.
Set scan tool MB991502 to the data reading mode for item 21, Engine Coolant Temperature Sensor.
The engine coolant temperature and temperature shown with the scan tool should approximately match.
Turn the ignition switch to the "LOCK" (OFF) position. Q: Is the sensor operating properly? YES: Go to Step 6. NO: Refer to, DTC P0116 - Engine Coolant Temperature Circuit Range/Performance Problem, DTC P0117 - Engine Coolant Temperature Circuit Low Input, DTC P0118 - Engine Coolant Temperature Circuit High Input.





STEP 6. Using scan tool MB991502, check data list item 25: Barometric Pressure Sensor.


Turn the ignition switch to the "ON" position.
Set scan tool MB991502 to the data reading mode for item 25, Barometric Pressure Sensor.
When altitude is 0 m (0 foot), 101 kPa (29.8 in.Hg) .
When altitude is 600 m (1,969 feet), 95 kPa (28.1 in.Hg) .
When altitude is 1,200 m (3,937 feet), 88 kPa (26.0 in.Hg) .
When altitude is 1,800 m (5,906 feet), 81 kPa (23.9 in.Hg) .
Turn the ignition switch to the "LOCK" (OFF) position. Q: Is the sensor operating properly? YES: Go to Step 7. NO: Refer to, DTC P0106 - Barometric Pressure Circuit Range/Performance Problem, DTC P0107 - Barometric Pressure Circuit Low Input, DTC P0108 - Barometric Pressure Circuit High Input.





STEP 7. Check connectors B-17, B-18, B-20, B-22 at injector for damage.

Q: Is the connector in good condition?

YES: Go to Step 8.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 14.

STEP 8. Check the injector.








Disconnect each injector connector.







Measure the resistance between injector side connector terminal No. 1 and No. 2. Standard value: 13-16 ohms [at 20 °C (68 °F)] Q: Is the resistance between 13 and 16 ohms [at 20 °C (68 °F)] ? YES: Go to Step 9. NO: Replace the injector. Then go to Step 14.










STEP 9. Check connector C-121 at ECM or connector C-120 at PCM for damage.

Q: Is the connector in good condition?

YES: Go to Step 10.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 14.
















STEP 10. Check for harness damage between injector connector and ECM connector or PCM connector .


Check the harness wire between injector connector B-22 (terminal No. 2) and ECM connector C-121 (terminal No. 1) or PCM connector C-120 (terminal No. 1) when checking No. 1 cylinder.
Check the harness wire between injector connector B-20 (terminal No. 2) and ECM connector C-121 (terminal No.14) or PCM connector C-120 (terminal No. 9) when checking No. 2 cylinder.
Check the harness wire between injector connector B-18 (terminal No. 2) and ECM connector C-121 (terminal No. 2) or PCM connector C-120 (terminal No. 24) when checking No. 3 cylinder.
Check the harness wire between injector connector B-17 (terminal No. 2) and ECM connector C-121 (terminal No.15) or PCM connector C-120 (terminal No. 2) when checking No. 4 cylinder. Q: Is the harness wire in good condition? YES: Go to Step 11. NO: Repair it. Then go to Step 14.
STEP 11. Check the fuel pressure.
Refer to On-vehicle Service - Fuel Pressure Test.

Q: Is the fuel pressure normal?

YES: Go to Step 12.

NO: Repair or replace it. Then go to Step 14.

STEP 12. Check for entry of foreign matter (water, kerosene, etc.) into fuel.

Q: Are there any abnormalities?

YES: Go to Step 13.

NO: Replace the fuel. Then go to Step 14.






STEP 13. Replace the injector.


Replace the injector.
Carry out a test drive with the drive cycle pattern. Refer to Trouble Code Diagnosis- OBD-II Drive Cycle - Procedure 2 - Fuel Trim Monitor.
Check the diagnostic trouble code (DTC). Q: Is DTC P0171 set? YES: Replace the ECM or PCM. Then go to Step 14. NO: The procedure is complete.
STEP 14. Perform the OBD-II drive cycle.


Carry out a test drive with the drive cycle pattern. Refer to Trouble Code Diagnosis- OBD-II Drive Cycle - Procedure 2 - Fuel Trim Monitor.
Check the diagnostic trouble code (DTC). Q: Is DTC P0171 set? YES: Repeat the troubleshooting. NO: The procedure is complete.

deadbeatrec

iTrader: (9)

A Vacuum leak will throw a CEL system too lean.
Faulty MAS (Mass Airflow Sensor) will throw a CEL also.
Faulty TPS (throttle Position Sensor) and ISC(Idle Speed Controller).
Faulty FPR (Fuel Pressure Regulator) and Fuel Pump.

-PCV Valve (Hold it parallel to the ground and jiggle it side to side. Then without moving much blow into the threaded side. If should blow freely. If you feel resistance which then opens up after you blow harder you need to replace it. You can also turn the PCV valve with the threaded side pointing the ground while blowing into it. If it plugs then it needs to be replaced.)

-EGR valve stuck in open position (Remove and clean with Carb cleaner. Ensure the valve closes completly and without excess resistance)

-Mass Airflow Sensor (Use a MAF cleaner to remove grime from the sensor.)

-Loose bolts (Intake Manifold to throttle body and also Intake Manifold to Engine Block)

If the above all check out then do a pressure test.
- Remove the intake and pressurize from the throttle body on
- You can use Brakleen, Intake & throttle Body Cleaner, Carb Cleaner etc and spray it over where you suspect leaks (Throttle body to intake manifold, intake manifold to engine block, all vacuum connections, AND the FUEL INJECTOR INSULATORS(Little black rings in between the fuel injectors and the intake manifold)

If you've removed the fuel rail from the Intake Manifold at all these spacers should be replaced. The spacers get hard after a while due to repeated exposure to fuel. They lose there flexibility and usually don't seal correctly. The injectors will never seal perfectly the same way as before so you need a spacer that has good flexibility to seal the gap correctly. These can either be purchased at your dealership or at most auto parts store.

-If you've done all the above then your problem is most likely not a vacuum leak.

Other causes for a rough idle can be faulty O2 Sensor(Will throw a CEL), Damaged Catalytic Converter(Will throw a CEL), Incorrect Spark Plug Gap, Damaged Spark Plug Boots/Wires(Should show signs of arcing across the tops), or dirty fuel injectors.

Well just wanted to share some information I've learned. If anyone wants to add anything feel free, maybe we can make this a sticky or something.

deadbeatrec

iTrader: (9)

would i know if i had a clogged injector? also how log does the fuel filter on the pump last? i have had it in there about 40,000 miles. it was very clean when i put in the pump at like 8-10,000 miles. would this cause the code?

i made 504whp in feb the wat the car sits now, well i did change the TB seals, so maybe more now. but my question is, would the car run great still in open loop if i had a clogged injector or a dirty fuel filter?

gsrboi80

iTrader: (38)

Yes you would check the injector resistance with an Ohm meter and the wire harness unpluged.

Do you have the stock injectors? Pop them in set the stock scaling and latency back to stock just dont go boosting the heck out of it. CEL come back yet after this?

deadbeatrec

iTrader: (9)

what? i dont have stock injectors nor do i have them laying around. and i dont have any tuning software to set them to the stock latency.

caLi4G63

iTrader: (40)

since you have aftermartket injectors, unplug each one from the harness and check the resistance of each one, even though you don't know what they should check out at, they should be very close if not the same to each other; i doubt they're all bad, if you do have a bad injector it will have a noticeablly different reading from the rest. This still won't help you notice if you have a clogged injector but I doubt you do.

although i think you're getting far from the problem by checking multiple things; if you started getting the lean code after you did the TB seals, you're problem might be associated with the replacement of the seals. check the vaccum hoses off the TB, check for voltage into the TPS (5volts usually), check the reading coming out of the TPS when you gradually open and close the throttle. Make sure your plugs are properly connected, you don't have a stretched/disconnected or damaged wire. let us know if you find anything, good luck!

RazorLab

iTrader: (8)

Have you logged your fuel trims? Never take peoples word that the "injectors are scaled fine"

Logging your fuel trims is easy and at least you would know if the trims are within spec or not and you can move onto more trouble-shooting.

deadbeatrec

iTrader: (9)

i dont have a lap top.