Hey all,
2000 Honda Accord 2.4 manual transmission. Was driving it home when it started misfiring. (Bucking, losing power, flashing check engine light) once I got to the mountain to get back to my house, it lost all power. After letting it sit on the side of the road, I was able to get it back home. Ran the codes, it’s giving misfire on all cylinders. Here’s what I’ve tried:
New spark plugs New wires New distributor Conducted compression test (all good) Conducted fuel pressure test (all good) Checked valve lash Checked timing (new belt, not out of time) Tested MAP sensor (testing good, but who knows) Sprayed for vacuum leaks
I’m at a loss here. Now, when you start it cold, it will run for a few seconds, then sputter out and die. Once it warms up, it will idle fine, but will not rev. If you spark some starter in the air box, it will rev right up, which I think is interesting. Could that mean fuel issue? Any ideas would be helpful!
Could be bad AFR caused by a failing MAF/MAP sensor, fuel delivery problems or restricted blocked CAT (exhaust).
A failing MAF/MAP sensor will usually be detected by the ECU and a code generated.
If spraying accelerant into the airbox causes the engine to smooth out then it would indicate lean AFR - fuel delivery issues.
Fuel injectors are very sensitive to changes in fuel pressure. A lot of early model fuel injected vehicles got sent to the wrecking yard because owners & workshops were unable to diagnose fuel delivery problems. To detect fuel pressure drops and fuel flow issues you really need to check fuel pressure under load conditions as opposed to no-load (neutral/idle speed - negligible fuel consumption). Manufacturers corrected this by installing a fuel pressure sensor to the fuel rail so that the ECU could monitor fuel pressure.
Under heavy load conditions the engine’s fuel consumption approaches MAX requiring a large amount of fuel (MAX flow rate) in which the delivery system is unable to supply, so the engine runs lean (lean AFR), hesitates, bucks or stalls. To recreate the problem under load, find the steepest hill in your area then floor the accelerator (WOT) when the car is at the beginning of the incline. Safety precautions - make sure the road is clear and there are no cars behind. Should the engine stall, may need to use a key-on/key-off sequence to allow the pump to build up fuel pressure before attempting to start the engine.
This problem will progressively get worse until it’s so bad it can be recreated under no-load condition. i.e. stationary in neutral. Try flooring the accelerator pedal in neutral. In the meantime owners need to avoid loading the engine by feathering the accelerator pedal. With the engine running lean (starved of fuel), the engine temp will run hot so keep an eye on the dash temp gauge and pull over and stop the engine should it enter the red zone.
Most fuel delivery problems are caused by a failing fuel pump or fuel regulator. Check the pump’s electrical circuit before replacing it. For DIYers, ScannerDanner has some good videos on diagnosing a failing pump including electrical circuit tests.
A mistake some DIYers make is to replace the pump and filter without checking the fuel tank for accumulated dirt and debris.
Re-posting original post as OP deleted account.
2000 Honda Accord 2.4L manual transmission.
Was driving it home when it started misfiring. Systems are bucking, losing power, flashing check engine light once I got to the mountain to get back to my house, it lost all power. After letting it sit on the side of the road, I was able to get it back home. Ran the codes, it’s giving misfire on all cylinders. Here’s what I’ve tried:
New spark plugs New wires New distributor Conducted compression test (all good) Conducted fuel pressure test (all good) Checked valve lash Checked timing (new belt, not out of time) Tested MAP sensor (testing good, but who knows) Sprayed for vacuum leaks
I’m at a loss here. Now, when you start it cold, it will run for a few seconds, then sputter out and die. Once it warms up, it will idle fine, but will not rev. If you spark some starter in the air box, it will rev right up, which I think is interesting. Could that mean fuel issue? Any ideas would be helpful!