What now?
05-01-2010, 11:04 AM
#11
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My car doesn't run rough all the time, just intermittently.Is it possible that my EGR is malfunctioning intermittently and thus causing the P0171.Once the motor gets hot(200degrees) then it'* hard to restart.I sometimes have to wait 30 minutes or more for it to start(luckily I have a very good battery) and when it "catches"I have to "goose" the throttle to get it to smooth out and run right.It also gives off a weird smell when it does this.When I had the Throttle Body off I noticed the EGR tube looked good(I didn't remove it though).
05-01-2010, 11:15 AM
#12
Retired
Certified Car Nut
If you have to give it a little goose to start it, it sounds like your Idle Air Control valve is sticking closed preventing air from entering the engine.
Sometimes carbon buildup prevents the valve from opening up. Remove the 2 screws, pull the valve out, clean the pintle with carb and choke cleaner and squit some inside the port where the pintle seats.
Sometimes carbon buildup prevents the valve from opening up. Remove the 2 screws, pull the valve out, clean the pintle with carb and choke cleaner and squit some inside the port where the pintle seats.
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2002 *-10 5.7 V8
2023 Jeep Rubicon Diesel
Retired Administrator
2002 *-10 5.7 V8
2023 Jeep Rubicon Diesel
05-02-2010, 11:11 AM
#13
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My check engine light doesn't come on until the car get'* hot.Wouldn't a cracked EGR tube give a P0171 code immediately?
05-08-2010, 09:17 AM
#15
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Have you ruled out all of these items these are the first things FSM suggests to check.
DTC P0171 Fuel Trim System Lean
Diagnostic aids
Diagnostic aids
- Heated oxygen sensor wiring. The sensor pigtail may be routed incorrectly and contacting the exhaust system.
- Poor PCM to engine block grounds. Ensure that the PCM grounds are clean, tight, and in the proper locations. Refer to Ground Distribution in Electrical Diagnosis.
- Fuel pressure. The system will go lean if pressure is too low. The PCM can compensate for some decrease. However, if fuel pressure is too low, a DTC P0171 may be set. Refer to Fuel System Pressure Test.
- Fuel injector(*): Refer to Fuel Injector Coil Test.
- Vacuum leaks. Check for the following conditions:
- Disconnected or damaged vacuum hoses. Refer to Emission Hose Routing Diagram.
- Incorrectly installed or malfunctioning crankcase ventilation valve. Refer to Positive Crankcase Ventilation Valve.
- Vacuum leaks at the throttle body, EGR valve, and intake manifold mounting surfaces.
- Exhaust leaks. An exhaust leak may cause outside air to be pulled into the exhaust gas stream past the HO2S, causing the system to appear lean. Check for exhaust leaks that may cause a false lean condition to be indicated. Refer to Exhaust System .
- Mass Air Flow sensor. Disconnect the MAF sensor and see if the lean condition is corrected. If the lean condition is corrected with the MAF sensor disconnected, replace the MAF sensor. Refer to Mass Air Flow (MAF) Sensor Replacement .
- Fuel contamination. Water, even in small amounts, can be delivered to the fuel injectors. The water can cause a lean exhaust to be indicated. Excessive alcohol in the fuel can also cause this condition. Refer to Alcohol/Contaminants-in-Fuel Testing Procedure .
- Poor connection at the PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
- Damaged harness. Inspect the wiring harness for damage.
- If the harness appears to be OK, observe the HO2S 1 display on the scan tool while moving connectors and wiring harnesses related to the engine harness. A change in the display will indicate the location of the malfunction.
05-15-2010, 05:13 PM
#16
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I checked my fuel pressure and it is confirming what I suspected.20lbs.!!!!!!!!So I'll be replacing my fuel pump either later today or tomorrow.
05-17-2010, 11:29 PM
#17
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Thread Starter
I changed the fuel pump and sending unit and now I have 45psi.The car starts quickly now and seems to have more power.Now the real test will be the morning commute to Brooklyn.Will post a follow-up tomorrow.
05-18-2010, 02:12 PM
#20
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Well I made the trip into Brooklyn smoothly and now I decided to hook up my code reader and check for pending codes and lo and behold PASS.
I learned a good lesson this time...when dealing with fuel injection you MUST check your fuel pressure first.I tried solutions that worked for my previous Bonne but now realize I was just guessing.At least now I have a clean throttle body and an engine that'* in great tune.Thanks again guys for you help.
I learned a good lesson this time...when dealing with fuel injection you MUST check your fuel pressure first.I tried solutions that worked for my previous Bonne but now realize I was just guessing.At least now I have a clean throttle body and an engine that'* in great tune.Thanks again guys for you help.
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