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@BrewDay09 Interesting you bring this up, I spent some time just this morning digging into this. Honda recommends using a YA40004 (Snap-On) 0-30 in.Hg Vacuum pump to conduct tests of the system, but they only provide instructions if there is a DTC code, which I do not have. With each of the DTC codes there is a set of additional parameters such as using the HDS and mucking around with the ECM connectors. But there is no stand alone test for the Purge Valve with no DTC.
I'm not opposed to buying a new tool and trying it, but how exactly do I test this when I have no DTC code?
Understood that you don't have a DTC. You may have caught the fuel trims before they got bad enough to throw a code.
But you can still check the physical operation of the purge valve which you suspect may be sticking open. Refer to page 11-78 instead of the procedure you referenced above.
Essentially just warm up the car, shut if off, and pull a vacuum on the purge valve. The warm up should cause it to open and dump from the canister. Shutting the car off should close the valve. If it holds vacuum it is not stuck open. If it leaks, Bob's your uncle.
Ok, this makes sense. I know this is a 'what if' question, but what if the gauge shows it holds a vacuum but my other test of plugging the lines shows it is not working properly.
@flanders and @fatjoe10 can probably comment on that, but I think the test you did of plugging the lines simulated the valve being closed. Stuck closed would not give you the fuel trim issues since that would mimic normal operation where there are no evap vapors purging into the manifold.
I think I understand this, I've ordered the gauge, it's only $27 including shipping, it's a useful tool to have. But the tool will also only tell part of the story, if there are some electrical shenanigans within the purge valve, that would be more consistent with this issue. As you've pointed out it was most likely a matter of time before a DTC is tripped as at times I'm getting -17%+ STFT and -17%+ LTFT.
My gut feeling is that a new purge solenoid is still needed, and if it's not the solenoid then some kind of a voltage or current issue behind it of which I'm not sure how to test down the line.
it will be interesting to see if the car runs any differently once you get this sorted out. Technically the pcm is keeping the car running properly by trimming out the fuel mixture as it is designed to do. At the end of the day it might just be peace of mind that you end up with, which is good.
A quick check is to do a resistance check on the valve itself.. if it shows OL, that's a fast way to determine if the purge valve is electrically failed.
A quick check is to do a resistance check on the valve itself.. if it shows OL, that's a fast way to determine if the purge valve is electrically failed.
What does OL mean (open loop?)? I can add resistance check to the test sequence as well (once I know what OL means)
it will be interesting to see if the car runs any differently once you get this sorted out. Technically the pcm is keeping the car running properly by trimming out the fuel mixture as it is designed to do. At the end of the day it might just be peace of mind that you end up with, which is good.
100+ HP guaranteed, minimum.
Seriously I think better gas mileage. In heavy bumper to bumper city grind like in LA I get about 13-14 MPG. But on an extended road trip to the middle of no where in the desert, 28 MPG. Which is consistent with the findings as the crazy high negative fuel trim is only happening at idle. As sson as there is any load, like fans or AC turned on, the trim starts to get better.
09-19-2019, 08:04 AM
