Originally Posted by rtaksokhan

Hi there! New to this, and so here it goes. I own a 2001 Honda Accord 4-Cylinter 2.3 Liter ULEV (ultra low emission vehicle). The emission system on this vehicle is built to California spec and so it's a little different than other Honda Accord types. Anyhow, I've been hit with a couple problems recently with this vehicle, which are expected at this point . It has 230,000 miles! All my problems started with my fuel pump dying one morning. I was driving to work and my engine shut off without any Check Engine lights, warnings etc.. Symptom: After stranding me on side of road, engine would crank but would not start up anymore. So, not knowing what is wrong with car…. performed following tests to find the problem:
1) Fuel Pump Voltage test: Hooked up voltmeter strobes to fuel pump’s electrical wires and noted close to battery voltage when ignition in II Position. (This lead us to move onto other tests, since it was within range)

2) ECM Relay: Swapped the ECM relay with another one, and attempted to start. Cranked but no start still.
3) Spark test: Hooked up special cable to spark plug, and attempt to start car. Noted that spark plug testing bulb lit up successfully for each cylinder (tested all 4 cylinders 1 by 1)
4) Fuel Pressure test: Rented a fuel pressure test kit from AutoZone. Hooked up to fuel hose (hose that leads into fuel pressure regulator) , Then with gauge attached, switched ignition to cranking position. Noted VERY LOW fuel pressure. Supposed to be 47 to 54 Psi according to Service Manual, and I was getting only between 15 to 20 Psi.
5) Bought new Fuel Pump, and replaced. Problem Resolved and car would start up again!

NEW/CURRENT ISSUE: All was good for about 2 weeks, until I ran into a new issue: Check Engine light came on, drop in fuel efficiency and engine is no longer running like it used to. Seeing a sudden loss of performance and power, while revving from idle. Idle is very rough. The immediate codes thrown were:
P0170 Fuel Trim Malfunction (Bank 1)
P0171 System too lean (Bank 1)
Did following to narrow down to no avail:
1) Replaced downstream (secondary, after catalytic converter O2 Sensor since had not been changed and I've had car since 30,000 miles (now 230,000 miles). Cleared codes and rescanned. Codes did not go away after clearing, and actually two new codes came P1167 and P1166 (Air/Fuel Ratio Sensor 1 Heater Circuit Malfunction) Same performance problem: longer ignition turn before start, engine stutters and shuts off when pressing on the gas pedal to bring RPM above idle.
2) Then replaced upstream Primary O2 heated sensor (primary, exhaust manifold), cleared codes and rescanned. Noted same symptoms as above and observed that when engine warms up to idle RPM, it's choking and stuttering. It shuts off after struggling to stay on. So, symptom got worse. After rescanning the OBD codes, the previous codes disappeared and NEW code thrown: P1399-Random Cylinder Misfire Detected.
3) Did compression test on all four cylinders, and got 190 Psi reading for each of 4 cylinders. Visually inspected my spark plugs and looked fine also.
4) Did a random clear and rescan of codes after compression test, and threw P0108 (MAP Sensor faulty). So, then replaced MAP sensor that goes into air intake with a new one. Started up car and cleared codes, and rescanned. This time got same code P1399 and same performance issues. When idle and pressing on gas pedal car struggles to go up from 0.5 and shuts off. IDLE IS VERY ROUGH.
5) Next, thought it could be a sticky Throttle or bad Throttle Position Sensor. Removed the Throttle Body, cleaned with carb cleaner and mounted back on. (did NOT change the TPS sensor though) and same poor performance. This time though threw 7 OBD codes:
P0122, P0300, P0301, P0302, P0303, P0304, P1399

I have run out of ideas and put way too much time (and money) trying to figure out the cause of the poor performance problem. I am not sure I can trust the OBD codes anymore. Anyone have any ideas??? Again, the engine symptoms:
Check Engine Light ON
Idle is rough
When pressing gas to go up from idle RPM, enging struggles and popping noise can be heard (misfire)
It appears as original OBD codes mentioned, System is running lean (too much fuel). I am out of ideas, please help me.