ktrayner68

Today I was sitting in my '04 TSX while the engine was running in the store parking lot talking on the phone. After my phone call i turned off the engine and went into the grocery store for about 30 minutes. When i came out and started my car it would not stay started and the engine light was on. It would idle low and then die. After i let it cool down for 30 minutes i was able to get it started and drive home about 4 miles.
We connected it to the lap top and it gave a P0171 code. So now I need to start troubleshooting to pinpoint the problem.

1. Where do I check fuel pressure and what should it be?
2. How can you check fuel flow to determine a blockage?
3. Where do i check manifold pressure and what should it be and at what RPM?

Any help would be greatly appreciated.

TexasHonda

P0171 can be an intake air leak (vacuum leak), or a blocked fuel injector. See attached procedure.

However it's easier to check for air intake leak if you have a obd2 scanner that reads fuel trim (LTFT and STFT). Idle car and check fuel trims (likely high +30% total LT + ST trim). Next increase engine speed to 2500 rpm and see what fuel trims do. If they go down significantly, an air intake leak is very likely. Locate w/ smoke test or water spray test (listen for idle change as water sucked in).

If total fuel trim similar or higher at high speed, then fuel delivery issue; weak fuel pump, fuel leak, fuel injector problem (blocked or damaged electrically).

good luck