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.

 

A lean engine means too little fuel. Really, the engine computer can not open the fuel injectors long enough to get the O2 sensor to read like you are getting proper combustion.

The OBD code provides a circuit the computer determines is outside of a set value. The real problem has to be diagnosed and can be a sensor (most people replace without any testing), the wiring, the computer, or something upstream causing the problem.

If your scanner can read live data, take a look at the fuel trim (both short term and long term). A perfectly running engine should have zero fuel trim. You can use the fuel trims to help figure out what is going on with your engine.

Also, what are the wire colors going to the map sensor? What are the wire colors going to the TPS sensor?

Here is a good video explaining fuel trims:
Also a good video on diagnosing lean codes.

 

Did you replace primary air/fuel (AF) sensor w/ the correct AF sensor? I have heard of folks accidentally purchasing an O2 sensor that would connect normally but cause many problems.

good luck

 

I'd probably recheck the fuel pressure, just to be sure it's not a pressure regulator problem. I only say that, as you've got multiple "fuel related" issues going on that a double check wouldn't hurt at this point.
Next, I'd make sure you installed the right O2 sensor in it, because I think the ULEV engine uses a different one from the rest of the F23 family.

Did you ever get another rear O2 sensor code? Just asking as a clogged cat can cause some of the issues you're dealing with.

 

Hi TexasHonda!
Thanks for the tip. Yes, I have double-checked to ensure I have the correct O2 Sensor which is built to spec for my ULEV type Engine F23A4 California standard emission.

At this point, all comments here and troubleshooting done on my end, point to TPS sensor for now. I'll keep everyone posted.

 

It is very easy to switch the TPS and the MAP sensor plugs. What are the wire colors going to the MAP and TPS?

 

TPS wires RED/BLACK.
MAP wires RED/GREEN.

*Bad news, I replaced my TPS sensor and it did not fix the problem. I crank, engine starts perfectly, when it's cold IDLEs just fine. When it warms up and RPM drops to the 0.5 mark, if I press down on gas pedal, car shuts off. I re-rented the Fuel Pressure kit from Auto Zone, and looks like we have low fuel pressure again. It's at 20 Psi, which is far below the minimum required of 36 to 48 Psi (Haynes Book). I'm going to recheck the Fuel Pump as "The Toecutter" mentioned up above. I bought the cheap Fuel Pump $50 bucks or so as opposed to the $120 something (Bosch) one from Autozone. Not sure if the pump is bad, or debris are caught in line. Either way after all the sensor replacements I've done so far, looks like issue is pointing back to a fuel problem again. GRRRR

 

Did you clean out the fuel tank when you did the replacement? Did you replace the sock filter? Debris in the fuel tank can destroy a fuel pump quickly.

If you unplug the vacuum line to the fuel pressure regulator, does the fuel pressure increase to normal?

It is possible that you are not getting the full 12V to the fuel pump when the wiring is plugged in. You would have to back-probe the connector on the power wire to see if the fuel pump is getting 12V. Testing for voltage at the connector with it unplugged can mislead you to thinking you have 12V when the wiring has current running through it.

 

I'm definitely keeping my fingers crossed on this one. I replaced/exchanged the original Auto Zone Fuel Pump (10 days since purchased from AutoZone) with another today. Problem has been resolved, and car no longer shuts off when I press on the gas pedal. Although, I am noticing some very weak and random hesitations. Definitely not like before where it wants to shut off. And the warmer the engine gets, the less it happens.

Wanted to thank everybody here for sharing all videos, questions and their experience. This has been an interesting and at times challenging issue. I am hopeful that the issue doesn't come back again. I'm thinking of moving onto fuel injector cleaning. They haven't been cleaned once, since owning the car (30k) with now 232k miles.

 

I didn't test disconnecting the vaccum line to FPR. I will test this on the new pump now, as I'm having very very minor hesitation at colder temp. With the new pump, car no longer shuts off and performance is SO MUCH better.