EVAP leak

Thanks for all the help. I believe my post from Saturday, August 25th, 2018 AT 12:29 PM confirms the gas cap is doing its job. Do you disagree? I am unclear on "It does sounds like the canister is leaking slightly". What suggests a canister leak? Per my post from Saturday, August 25th, 2018 AT 11:45 AM, the canister held 15-inHg vacuum for at least 10 minutes. The hoses and electrical may be at issue.

I may have some progress on figuring this out. In the following text, the numbers in parenthesis correspond to pictures I have attached to this post. (01) The Haynes Accord 1998 and 1999 manual discusses disconnecting (and testing) the two-pin connector from the purge control solenoid. (02) The Haynes manual provides an illustration showing terminal 1 on the left and terminal 2 on the right. (03) The third picture shows the actual connector on my Accord, with what I think also shows terminal 1 on the left and terminal 2 on the right. (04) The fourth picture simply puts a red circle on what I think is terminal 2. (05) The fifth picture shows that with the key turned off, I measured 17.7 ohms between vehicle ground and the terminal that I circled in the prior picture. (06) The sixth picture shows that with the key in the ignition in the on position, but engine not running, I measured 12.09V between vehicle ground and the terminal that I circled in the earlier picture.

Note that I tried measuring between the other terminal (the one that was not circled) with the key on and with the key off, and never found any indication that there was a connection. I tried, but never measured continuity to ground, and tried but never measured any voltage from that terminal to ground. I will try that again tomorrow. I think this indicates that my harness is improperly wired. If it is as I think, that would say that my Purge Control Solenoid has not been opened by the PCM in months, pretty much the entire time I have had this problem.

The Haynes manual also mentions checking the harness from the purge control solenoid to the number 6 fuse (15 amp). How do I locate that fuse? There are some under the hood, some near the dash on the driver's side, and some near the dash on the passenger side.

I had some other work done on the car (transmission rebuilt) a month or so before the problem appeared. Maybe something went wrong with that activity.

Following my Saturday, September 1st, 2018 AT 6:00 PM post, I did take a few more measurements with my volt meter/ohm meter, and perhaps things are as they should be regarding the Purge Control Valve solenoid harness.

If I use T-pins to back probe the connector, that makes the pin on the left the one that should have battery voltage when the key is on. Back probing also allows the connector to be attached to the solenoid. If I attached the connector to the solenoid, the 12 volts shows up on both pins, but only when measured between the pins and ground.

When the connector is disconnected from the solenoid, the black/yellow wire is the one that gets the 12 volts when the key is on, but when the key is off, it is shorted to ground, which I found surprising. When disconnected from the solenoid, the red/yellow wire on the other connector terminal never shows any continuity to ground, and never shows battery voltage.

It may be that while driving, the PCM switches the negative side (via the red/yellow wire) when conditions are met to do that. The Haynes book shows the red/yellow going from the Powertrain Control Module at a point labeled PCS over to the evaporative emission (EVAP) purge control solenoid valve. What does PCS mean? The black/yellow wire goes from the purge control solenoid back over to the Powertrain Control Module at a point labeled VBSOL. What does VBSOL mean?

I also figured out that fuse is on the driver's side under dash fuse box. I checked the fuse with my ohm meter and it is good. I may have done that earlier - this has been a long time detective job with many other things going on between attempts to figure this out.

I have attached a picture labeled "Parts to check for leaks related to P1456". The only part attached to the fuel tank that I can replace is the fuel cap, and that has been done. I have also shown that the Fuel Tank Pressure Sensor indicates that the tank will hold vacuum until I remove the fuel cap. I am thinking it is worth replacing the EVAP two way valve just to see if the problem goes away. There is not much else on the tank side that I could fix, other than perhaps the bypass solenoid, but that also seems to work.

I changed the two-way valve. Then I cleared the codes. The fuel tank is very low so I will drive to go fill up, and will end up driving at least twenty miles today. I hope this fixes it.

The old two-way valve had some fuel in it, which cannot be a good sign. When I took it off, it appeared to not have any o-rings. The new one came with two o-rings. I put those on before installing the two way valve onto the evap bypass valve. After I had everything together, I found one o-ring under the car. I hope it was from the old one, but will go forward and test drive anyway.

Now I have a P1457. I am not sure if that is progress, but it could be. I suppose I need to check the two-way valve to make sure I have the o-rings. If I find fuel in the two-way valve, I suspect there is a problem with the ORVR valve, or why else to I have fuel in the two-way valve? If there is no fuel in the two-way valve, I think that suggests the ORVR valve is ok, since P1457 indicates a problem somewhere between the two-way valve and the purge control valve. My next guess is actually the canister vent valve based on some prior testing. I wish I knew how much vacuum the canister vent valve is expected to hold.

OBD Fusion indicates I have Mode $06 Component ID $01 TID $2E value equal to 0, which should be minimum of 8 on 1998 Accord LX 2.3L Automatic. Any clues on what that means will be greatly appreciated.

Should I move this over to a P1457 thread now that the ODB II code has changed?

I recall smelling fuel while running the tests described in my "Saturday, August 25th, 2018 AT 12:29 PM" post. My 9/13/18 post indicated that I found some fuel in the old two-way valve that I replaced.

My 6/24/18 posts included pictures of what I thought might suggest a leak, and we ruled that out. Today I do not see anything more than that.

The fuel cap was replaced 7/1/18 and that did not solve the problem. My "Saturday, August 25th, 2018 AT 11:45 AM" post showed that rubber plugs and a hand-held vacuum test indicate the canister is not leaking, but there may have been an indication of a problem with the canister vent valve, which was only able to hold about 8-inHg of vacuum. How much vacuum should the canister vent valve hold?

I have read that P1457 cannot be detected until the P1456 test passes. Is that the case? That would seem to explain the immediate ( 50 miles of driving following repair) change from P456 to P1457 following replacement of the two-way valve.

Thanks for all the help.

I found out that VBSOL refers to Power source for solenoid valves.
https://techinfo.honda.com/rjanisis/pubs/web/RJAAI001_acronyms.htm.

I had P1456 when this saga began, and that changed to P1457 when I replaced the two-way valve.

The P1457 became very predictable. Drive the car twice, MIL comes on and code is P1457. I decided to remove my fuel cap before starting my engine this morning. The whoosh of air (or fuel vapor) that I heard when opening the cap made it quite clear that it had been air tight. Should it have been? I could not tell if the whoosh was releasing vapor pressure, or if perhaps I had a vacuum inside the tank due to lower temperature overnight. I thought the Canister Vent Valve should have been open while the car was parked overnight, and the two-way valve should have been allowing fuel vapor into the canister while the canister vent should have let air escape to the environment. It was clear that there was either pressure or vacuum

Given how predictable getting a P1457 had become, I wondered if I could get the P1456 back by simply storing the gas cap in the trunk and driving. I was surprised to find that the MIL did not come back after several drives, but I do have a pending P1457.

In the course of the P1457 saga, I noticed that I started getting OBDII Mode $06 CID $01 TID $2E values of 0, where the minimum passing value is 8. I found that $06 CID $01 TID $2E is defined as EVAP_PCT, which elsewhere I found described as follows: "Shows the status of the Evaporative Purge Control Valve between 0% (no flow) and 100% (max. flow, max. duty cycle)."

That suggests that my purge control valve has a duty cycle of 0%, so it is never being commanded to open. Since that is the only failure indication I have other than the P1457, it seems fair to assume they are related.

From yet another source I found this: "EVAP PURGE = EVAP_PCT: This parameter is displayed as a percentage and is normalized for all types of purge systems. EVAP Purge Control commanded OFF will display 0% and EVAP Purge Control commanded fully open will display 100%. This is an important parameter to check if the vehicle is having fuel trim problems. Fuel trim readings may be abnormal, due to normal purge operation. To eliminate EVAP Purge as a potential contributor to a fuel trim problem, block the purge valve inlet to the intake manifold, then recheck fuel trim."

I do not have any indication of a fuel trim problem, but I haven’t been looking for that. I do think my mileage is lower than in the past, and I did find fuel in the old two-way valve that I replaced.

Here is some wild speculation that fits the facts. Maybe I overfilled my fuel tank and that caused fuel to make it to the two-way valve. That valve is designed to function with air and fuel vapor, but not with liquid gasoline. Maybe I have liquid fuel trapped between the tank and the two-way valve, and maybe driving without the cap for a day helped some of that dry out. I put the cap back on, but will remove it again in the morning. I will try to figure out if I have pressure or vacuum. I will drive another day with the cap off.

Or maybe I had a large leak that was fixed when I replaced the two-way valve, and now I have a small leak. Perhaps it is time to obtain a smoke machine and figure out how to use it. Is there a smart choice from tools on the market? Where would I find the green cap service port on my car?

I found a video indicating the two-way valve is a common problem causing P1456, and the canister vent valve is a common problem causing a P1457.

I found another video where a professional mechanic spent two hours using a very nice (OTC LeakTamer) smoke machine to try to locate a small leak. The gauge on the LeakTamer quantified the very small leak, but the smoke never revealed its location. Eventually the mechanic sprayed soapy water on the canister vent valve while pumping air into the system, and he got bubbles on the canister vent valve. I have done something like that to locate natural gas leaks before, but never imagined the car's instrumentation would be sensitive enough to detect such a small leak. Maybe it actually is that sensitive.

This brings me back to Ken's earlier suggestions about removing the canister, plugging the holes in it and checking for leaks. I did try to do that with some rubber plugs and a Mityvac hand powered vacuum pump and did not detect a leak. I used vacuum and the gauge on the Mityvac to try to detect a leak. Perhaps I should try again and simply use the Mityvac to pump some air pressure into the canister and put soapy water on the vent shut valve, and any other place that might leak.

I have attached pictures showing bubbles on a canister vent valve; these are not from my car, but simply partial screen grabs of someone else's video.

I am still expecting a new canister vent shut valve to be delivered soon, and I do not mind replacing it. I would very much like to first identify the leak so that I have good reason to believe the problem is fixed. I will try that, but even if I do not detect a leak, I will go ahead and replace the valve. If the problem persists, not sure what comes next.

I tested the canister again. I set this up with rubber plugs stopping all the canister holes except the vacuum source which I attached to a hand held vacuum pump. This time it held 10 InHg for over half an hour. (See first attached picture.)

I connected 12V to the canister vent solenoid with the rubber plug still in the canister vent solenoid outlet. I heard the solenoid click when power was applied but that did not change the 10 InHg. (See second attached picture.)

With the 12V connected I removed the rubber plug from the canister vent solenoid outlet. To my surprise, that did not change the 10 InHg. (See third attached picture.)

I was surprised because earlier testing a few weeks ago of this same set of parts being testing using the same tools I had slightly different results. In the earlier testing I used 15 InHg but with the 12V applied, when I removed the rubber plug the vacuum dropped to around 8 InHg. The 9/21/2018 test used 10 InHg but it held with the 12V applied and rubber plug removed. Since the 10 InHg held, I tried to increase the vacuum. I could pump it to around 12 InHg but now it would slowly drop to around 7 or 8 InHg before it would hold. This could be modeling what is going on while driving; the canister vent valve is closed while the manifold vacuum is applied, and there is no rubber plug to help hold vacuum. I think this likely suggests an internal leak. I was able to repeat pumping up the vacuum without the rubber plug in place, and it again slowly (seemed like less than 30 seconds) dropped to around 7 or 8 InHg. (See fourth attached picture.)

I had intended to next apply pressure (the hand held pump can generate vacuum or pressure depending on a valve setting) and use soap bubbles to test the canister vent solenoid, but I actually forgot to perform that test. Since on the same day I received a new (after market, not a genuine Honda part) canister vent valve, I went ahead and replaced the one that appeared to be leaking based on testing above. (See fifth attached picture, new part installed, old part next to canister.)

Test driving has been so far so good. I have driven it quite a bit, at least 35 †40 miles, and do not have a MIL. However, I have had a pending P1457, and am wondering how long it will take for that to either become confirmed or cleared. I will say that prior to replacing the canister vent solenoid valve, the P1457 with the [check engine light] MIL was a lot easier to produce, so things do seem better in any case. Similarly, when I recently replaced the two-way valve, I stopped getting P1456 and started getting P1457. The response was immediate and different from what I had seen a long period of time (months).

I have slightly less than half a tank of fuel at this point. If I get through that and the next tank of gas without a MIL, I will consider this fixed. I am hopeful, but still have that pending P1457.

Sadly the P1457 has returned. So far I have replaced the gas cap, two-way valve and canister vent solenoid, at separate times but in that order. Originally I had a P1456, but since replacing the two-way valve I have had P1457. I am going to try replacing the two-way valve bypass solenoid. It is a moving part and many people recommended replacing it when replacing the two-way valve.

I noticed that code detections almost always occur in the morning on the first drive of the day. Perhaps test driving right after replacing a part will not reproduce the drive cycle conditions needed as well as my morning drive.

Pictures of the next part to be replaced are attached.

I spent quite a long time trying to to locate the cause of the original problem, P1465. On 9/13/18, I decided to try replacing the two-way valve. I removed the old two-way valve and initially thought both O-rings had been missing between the original two-way valve and the original bypass solenoid. Since the new two-way valve came with both O-rings, I installed those with the new valve. After replacing the two-way valve, I found the original larger O-ring on the floor, so it must have fallen off while I was doing the job. The P1456 went away after replacing the two-way valve, but then I started getting P1457.

I found the original smaller O-ring, today, 9/24/18. It was inside the bypass solenoid, along with the new one that I had installed when replacing the two-way valve. That is a workmanship issue. I suspect the P1457 problem may be related to having two small O-rings installed where I should have installed one.

In the first couple pictures you can see the old two-way valve. It has some oil and dirt on it and it is sitting on a piece of tan cardboard. One of the pictures shows the original large O-ring installed on the lower horizontal opening but without the small O-ring on the horizontal opening just above that. The long vertical fitting is where a vacuum hose that leads to the tank pressure sensor is installed.

In the second couple of pictures you can see how the new two-way valve was improperly installed (because there were two of the smaller O-rings where there should have been one) onto the bypass solenoid. The additional small O-ring causes an uneven gap between the bypass solenoid and the two-way valve. Since (on 9/13/18) I replaced the two-way valve while the bypass solenoid was still installed on the car, I could not see this poor fit.

In the third pair of pictures you can see how the new two-way valve is installed on the new bypass solenoid, with the two O-rings where they should be, and no extra O-rings installed. I temporarily applied 12V to the new bypass solenoid during installation, as the air seal was otherwise making it difficult to get the small O-ring on the two-way valve inserted into the bypass solenoid.

I cleared the pending P1457. I have since driven this about 15 miles, with no pending codes so far. The car has about a quarter of a tank of gas remaining. I plan to drive it some more today, and then in the morning the way it was driven when codes were previously detected.

Replacing the gas cap on 6/30/18 did not fix the original P1456. I tested the canister itself for leaks on 8/25/18 and did not find any. The old two-way valve had fuel in it when I replaced it on 9/13/18. Replacing the two-way valve on 9/13/18 stopped the P1456 but started the P1457.

I again tested the canister itself for leaks 9/22/18. The only indication that there might be a leak was related to the canister vent shut valve. I replaced the canister vent shut valve on 9/22/18 but still had P1457.

The new two-way valve did not have fuel in it when I replaced the bypass solenoid on 9/24/18. Testing is now in progress.

I had a confirmed P1457 this morning. I took the canister off, plugged holes, pumped in a little air pressure and found that it would not hold that pressure, and if I listened carefully I could hear air escaping. I sprayed soapy water where the recently installed canister vent solenoid attaches to the canister and got bubbles, so I found a leak. The WVE/AIRTEX/WELLS (WVE 2N1136) canister vent valve / solenoid is something I installed when I recently started getting P1457. My prior canister leak testing (8/25/18 and 9/22/18) was based on vacuum rather than positive air pressure, and I had not used soap bubbles. The prior testing also used the original DENSO part. I never previously tested the new RockAuto recommended part when installed on the canister.

I suspected the canister vent valve / solenoid based on web searches for "Accord P1457". I now think the initial P1457 was actually due to the second small O-ring unintentionally installed when I replaced the two-way valve. There should be one large O-ring (which I had) and one small O-ring (but I had two) between the two-way valve and the bypass solenoid. The P1456 went away with the removed/replaced two-way valve, and the P1457 showed up after the new two-way valve was installed.

Web searches led me to suspect the canister vent valve / solenoid, but the part recommended by RockAuto for my car was either defective or would have never fit in the first place. Either way they will not refund my money since I had installed the part. I re-installed the DENSO canister vent valve / solenoid that came installed on my car from the factory, as the extra, second small O-ring (between two-way and bypass solenoid) seems like the original P1457 problem. The new part from RockAuto clearly leaks (see photo evidence) and it is disappointing to learn that they do not stand behind what they sell, but the $35 tuition taught me a lifetime lesson to shop elsewhere in the future.

Recap: The initial P1456 problem appears to have been caused by a failed two-way valve. The P1456 has not been reported since the two-way valve was replaced. P1457 showed up just after two-way valve was replaced, and I now suspect that was due to two small O-rings (I did not notice there was already one inside the bypass solenoid) where I should have had one. Before detecting the extra O-ring, I replaced the canister vent valve / solenoid, but the replacement part was either not the right part to begin with or it leaked well within warranty. The part seller could not care less. I re-installed the original DENSO canister vent valve / solenoid. Test driving so far indicates Evap System Monitoring is not continuous but is available on my car, and that testing completed. There are no pending codes and no confirmed codes. Furthermore the Mode $06 CID $01 TID $2E now has a value of 41 with a minimum of 8 needed to pass, which I have never seen since I started tracking when I got the P1457. As far as I can tell, that mode $06 info refers to EVAP_PCT, which is the duty cycle applied to the purge control solenoid, and the 41 would indicate the valve is activated 41% of the time.

I have what appears to be some encouraging news, but will continue to test, particularly in the morning when setting pending P1457 codes or confirming them has become quite predictable.

I sent email to service@rockauto. Com regarding the defective part. They replied in a timely manner and provided instructions to return the part for a refund.