So my 2015 Honda Accord Sport failed the air emissions test twice, and it’s been about a year trying to find the cause, with the acceleration starting to be affected
Symptoms:
Diagnostic Trouble Codes (OTC), reported during air emission fail:
P0088
P0455
P0456
-Engine light is always on.
-It will have episodes of weak/nonproportional acceleration when stepping on the pedal while at a stop, then car will jerk at around 30ish mph and then accelerate normal. Mostly happens at low fuel, but can happen at medium fuel. During these episodes the traction control and tire pressure lights turn on and flash. Then sometimes disappear when I start the car later.
-Had the EVAP Purge Control Solenoid/ Vapor Cannister Purge Valve replaced.
-Had fuel cap replaced.
-Engine sounds louder than average when I first start up car and drive the first mile, than returns to normal.
Thanks for any advice given. Really just wanna drive my car.
Would it be as simple as replacing the high pressure fuel pump? Because from what I’ve read it does match with the jerking motion that occurs sometimes when accelerating to and past the ~30mph mark. (Also, quick edit that I don’t know if its related, I had the EVAP Purge Control Solenoid/ Vapor Cannister Purge Valve replaced as well).
Also, would a high pressure fuel pump failure account for the flashing of seemingly unrelated lights like the traction control and tire pressure lights flashing occuring around the time when the low power at acceleration and jerking occurs?
Yeah, I’ve went to two mechanics/dealerships during that time. First one suggested a whole replacement of the fuel tank (did not go through with this since that seemed inconsistent with the issues), and the other was the one who replaced the fuel cap and the EVAP purge valve. Honestly, I don’t know if the second was also just yankin’ my chain or they honestly thought those were the solutions.
My guess, the emissions failure is caused by the two evap system codes. The leaks are causing the mixture to be overly lean, and the resulting poor engine performance.
The fuel pressure has to be correct of course, but if it were too high that would usually cause a too-rich code. Since you aren’t seeing that code, the problem may be the fuel pressure is actually ok, and the fuel pressure sensor is faulty.
Ask your shop if a fuel-trim test would be helpful toward resolving the fuel pressure code.
Appreciate the advice on the specific test. I was also suggested by the second dealership/mechanic to do smoke test (EVAP smoke test maybe?), would that help or is it anyway related to the issues?
The smoke test would help diagnose the two evap-leak codes. There’s several places leaks can occur in the evap system. The gas cap is one, but it appears you’ve already disproved that possibility. At the top of the fuel tank is another common one. A hose may have come off its connector or the rubber may have split. The purge and vent valves are other possibilities. A smoke test would usually show any of those as the cause without having to drop the tank first. But to fix a leak at the top of the tank location, the tank will probably have to be dropped.
You have two different issues, the P0088 is an urgent issue, especially if the check engine light/malfunction indicator lamp (CEL/MIL) is flashing. When that light is flashing, there is imminent damage to the catalytic converter occurring. The flashing of the other lights such as traction control and tire pressure is done to get your attention to the CEL/MIL. BTW, the flashing or steady traction control light means the traction control is turned off to prevent unattended acceleration.
As for the other two codes. They indicate a leak in the purge control system. Replacing the gas cap is a valid repair for a car owner to do as it is cheap and potentially it could save the cost of a visit to a mechanic. It has a good cost/reward ratio. That is not something a mechanic should automatically do. A good mechanic who is charging you for a diagnostic has the tools to verify defective parts. Unless the cap failed a valid diagnostic test, it should not have been replaced.
There are two valves in the evap system, a purge control valve and a vent control valve. There is also an absolute pressure (vacuum) sensor that the PCM monitors when these valves are commanded open or closed to determine if the system is working. Periodically, the PCM will command the purge valve to open and the vent valve to close. It expects to find a vacuum in the system. If there is no vacuum, then there must be a leak or the purge valve is not opening or the vent valve is not closing. The leak could be one of the hoses, the fuel tank, the gas cap or the charcoal canister. There are tests for these and they should be done first as some of these parts can be quite expensive.
One more thing, chronic overfilling at the gas station can damage these systems so it is best to not add any more gas after the nozzle shuts off, not even to round up to the next nickel/dime/dollar.
Okay so focus on the P0088 code first.
If I’m understanding this correctly:
Get a fuel trim test for possible issues with the high pressure fuel pump/system, since it might be the cause of the P0088.
And, then for the P0455 and P0456 codes, a smoke test.
Is there any other specific tests I should be focus on for the codes? Specifically as @Neveda_545 mentioned repairing the fuel rail pressure fault.
Yes, focus on the P0088 first. A mechanic should have either a factory service manual or a subscription to a service like AllData. These outline the specific steps that need to be taken to diagnose the issues. He (she) should have all the necessary tools. You can expect to be charged a fair diagnostic fee for this service, usually one, but occasionally two hours labor. Considering the cost of some of these replacement parts, the diagnostic fee is money well spent. I do not access to either of these for your vehicle so I cannot tell you what specific test should be done.
Vehicle repair is a business transaction. You should first solicit the names of good mechanics from friends and family. Then ask them what they are specifically going to do to diagnose your issue. If they respond that they are going to use the service manual or something like AllData, that is enough. If they respond with something like, “thats usually this part so we will just replace it”, then move to the next recommendation.
Edit: @Tester and I do not agree with the value of the overfill valve, aka rollover valve. I have great respect for him and his opinions, however we do not agree on this. That valve will jiggle when you are going down the road and that jiggling will let raw fuel get into places it is not supposed to get into.
But even if it does prevent gas from getting into the wrong places, overfilling reduces the space above the level of fuel for expansion of that fuel. It acts as a cushion, Gas comes out of the ground at around 60 ish degrees F. On a hot day it will expand in your tank quite a bit and will create quite a bit of vapor pressure. During that short time when the PCM decides to check the system and it is looking for a vacuum, that excess pressure will get into the vent system and could negate the vacuum, momentarily, but long enough for the PCM to detect a failure. Overfilling is just a bad habit to get into. But if you are not overfilling, then that is not the cause of your problem.
There is a PCM software update that might apply to the fuel pressure problem.
There dealer’s scan tool would have shown a notice of applicable service bulletins and software updates during the module scan, if nothing was indicated, the PCM update may have been performed in the past.
Now I think we are back to find a different Honda dealership.
A dealership should have determined if the update Nevada_545 posted had been performed.
All I read in your posts, replacing parts without performing a complete diagnostic.
BTW, do you have the diagnosis report from the dealership you used? Did they do one?
