I've seen enough EVAP videos for armchair confidence to grow, so it was more than a little humbling one day when it turned out to be more difficult than I expected. Modern cars have several check valves in the system that will change results depending on whether you apply positive or negative pressure during testing. What makes things worse is the way manufacturers may not explain the system well enough in service data for one to use logic to make a diagnosis. Instead they offer a cookbook sequence of tests they expect you to perform without fully understanding.
Yes exactly. That’s how I knew this particular system had the vacuum limiter valve. I never assume any car after 2005 is the “same ol EVAP system” I am familiar with so I always research it to see any differences. some of them are crazy complex.
Hahh I know what you mean Ju M. Sometimes there are “directional” valves and solenoids so you have to “go with the flow” literally to properly test them.
I didn't think the GROUND thing was so out of line. In fact I thought the GROUND thing was damn entertaining but then I don't live in the unGROUNDed corporate world. Keep doing what you do and keep your feet on the GROUND.
I see that this video was recently uploaded so I'm gonna tell this weird diagnostic story here and hope that matt reads it and stores it in his brain in case he needs it, and i hope the same for anyone else who reads this too. I had a 1998 mercury mountaineer 2wd 5.0v8. I came home one day and parked in my driveway, turned off the lights, turned the key cylinder to off, removed my key that had a chip in it, and the vehicle still ran. I walked a hundred feet or so away with the chiped key in my hand and yet the vehicle still ran. I had to remove the ignition fuse t to shut the vehicle off then disconnect the battery so it wouldn't go dead. The next day it shut off fine all day, but when I got home that evening a little after 5pm it wouldn't shut off again. I drove it to the shop near my house because the main mechanic who worked there was really really good. He had never seen that problem before. I stopped at 2 Ford dealers and talked to the main technicians who were supposed to be the best Ford guys but they couldn't tell me what it could be. When I got home I turned the lights off, turned the key cylinder off, removed the key, and opened the hood to disconnect the battery. I couldn't see what I was doing so I went to turn the lights on and when I turned them on the truck shut off. I couldn't believe that happened so I left the lights on and started the vehicle. I then turned the key to off position and the truck shut off just fine. I started paying special attention to the headlight switch and messed with it and noticed that it turned a few degrees past the off position(the off position was supposed to be at 12oclock). I started the truck and turned the headlight switch a few degrees past off(a few degrees past off was between 11:55 and 11:58), then turned off the key cylinder, and it would keep running, and then id shut the vehicle off by moving the headlight switch back exactly to the off position. I was able to demonstrate this perfectly every time. Turns out that the light switch being moved too far past the off position sends power to somewhere that keeps the car running. It was the weirdest problem I ever had to chase down. I hope this helps matt or someone else reading these comments.
that’s crazy. never heard of that before. I have run into other issues where a power crossed with other wires and did things like “every time I turn the lights on the wipers operate” but keeping a car running- that’s crazy fun!
We recently had a vent flow incorrect code on a 2005 camry that is set during the self-tests. The cannister etc. are much harder to get to than this KIA, so after checking basic solenoid operation with a scan tool, I checked the purge valve as it was the easiest. Luckily, it was a small leak there, just as in this case. 5 or 10 minutes with the scan tool sitting in the drivers seat on a wet day and 5 or 10 minutes to get out the vacuum gauge and find the leak. For a DIY guy like me, that was a major success and an opportunity to be thankful for the tools I do have.
You have no idea how much information I was able to gain from this simple video. Even though I drive a land rover, this explained a lot about my codes. I actually have both codes, a large leak, and purge. And lately, for the past 4 or 5 times I've filled up my tank before the code came, I was giving it an extra click after the automatic shut-off. Smh😢
Hey I’m not back door quarterbacking but just a little tip for future reference to keep in your arsenal that I use all the time in the shop with purge or evap codes. Go to the purge valve, unplug the hose going back to the fuel tank, and then unplug the electrical connector and then start up the car, if you feel vacuum then Bobs your uncle ya got a bad purge lol, cheers, been loving the videos
Good tip! I would have done that if I didn’t first think this would be a cannister problem. Hell actually if I wasn’t filming I would would have done the entire testing with bidirectional controls and use the tank pressure sensor for feedback.
@@SchrodingersBox lol yes agree, bidirectional and FTP sensor can usually give you a solid direction right from the jump, however that doesn’t make for great video content lol
Please no need to apologize for the "GROUND" video as far as I'm concerned. There isn't much in this world to laugh about these days and you really had me going! Besides this person had it coming. I can't get enough of these Evap videos, great job!
Glad to hear that, Dennis!! yeah it’s kind of funny- I actually have only had one EVAP issue as long as I have been doing this. Two in the past week is pretty odd but it’s great because most people are very unfamiliar with this system. Hell I actually watched my own video on EVAP to refresh my memory !!!!
Just something I’ve noticed with this with this code if you have live data you will see the ftp sensor show slight vacuum on the tank when you start the car as well as slightly negitive stft. Fuel tank pressure will also go back to atmospheric shortly after turning the car off … if you notice this while your doing a code scan it’s likely the purge valve isn’t sealed properly. If not I agree with you 100% go see if they over filled the canister! Great instructional video ! Keep up the good content!
Overfilling the tank (evap problems) and almost empty tank (overheat fuel pump), those "simple and harmless" things (and I can say I am guilty of those situations) can lead to a world of troubles. If one just do things right can save you money and time.
Your approach was just fine Matt. I have a little different approach for various reasons on Evap systems. Start with the purge to see if its leaking. If its good or bad you then have a great place to smoke the rest of the system. If purge is bad, there is still the possibility of a leak in the rest of the system. Once final repair is done, a lot of the scan tools have an evap system test you can run the car through to confirm repair and prevent comebacks. I have never worked on a KIA, so...
I agree that is a totally fair method and as a matter of fact, if I didn't think the guy overfilled with fuel I absolutely would have started at the purge as well.
Good thing you checked powers and GROUNDS on them components you can thank viewers for that fixall method! Btw thanks I've learned so much from this channel
incorrect flow could mean a lot of things it all depends on what the manufacturer defines as an incorrect flow and a faulty purge solenoid valve can activate that code. In my experience a faulty purge valve will usually set a small leak code but with this being a pressure tested system as opposed to a vacuum tested system it's hard to say what code would come up
The GROUNDS video, I was ROTFLMAOWPMP and my wife was wondering what was so funny about fixing a car. EVAP flow is typically measured by the fuel tank pressure sensor, while the running engine is vacuuming out the fumes, the pressure in the tank is going into a slight vacuum and the FTP sensor is reporting this to the ECM via a voltage change, this is the only way, for most vehicles, not TOY or HONDOO, find a small leak or large leak based on the time of the leak down, slow or fast voltage change, or never have a change (huge leak). Too much vacuum would equate to a crushed fuel tank LOL. This is a sign of overfilling when the engine runs rich after the gas station for a short period of time until that fuel in the EVAP Canister is all sucked out and then runs lean because the purge valve is stuck open and has finished sucking out all the fuel and now air only. You said you are totally doing this wrong, you are a teacher here brother, you mentioned doing an EVAP video already, where is your checklist of procedures to do these tests without doing it wrong? You hotwired the vent valve but you did not bi-direction test it to check the circuitry? This will come with the testing later with the scan tool, yes. You have the same problem as many, noted to be ScannerDanner, guessing what the problem is before testing and proving the fault, poisoning your own well again, bad habit brother but typical. Sorry, I just believe that an instructor should not make this type of mistake, guessing that is, I know you are much better than this, and editing videos is awesome. Doing a diag is not guessing even if you test something actually unimportant, if it is on your list of procedures, it's valid. As long as you follow your own procedures, starting to see a pattern now? It is a leak, but it's defined as incorrect flow because this leak is not in a hose or at the gas cap, it's flowing when it should not be flowing EVAP air (leaking), and it is showing a vacuum voltage to the ECM when there should not be any vacuum at this specific time, possibly found as part of a test strategy as opposed to the actual operation of the system, not sure if KIA does this type of quick test strategy? You see, if a hose or gas cap was leaking and the purge valve was closed fully, there would be no leak so the ECM knows there is what Kia calls incorrect flow, with or without another crack in the system elsewhere. I guess the hose from the purge valve to the intake could be leaking but the FTP sensor would not notice that either since that leak is on the other side of a good Purge valve, which has a vacuum all the time the engine is running so you only have a lean code now, not an EVAP system code, yes. I really respect your DIY system here on your LOW TECH Channel, I also wish for simple problems like this to use at least the scan data PIDs to show how the ECM knows why there is incorrect flow please, at the end of the video IMHO. In many scenarios, there will be an FTP sensor, but not always mounted directly on the tank but on the EVAP system for sure. Thanks again for the testing procedures with no fancy equipment.
MATT, you always amaze me brother with ur approach and thought process you will be AWESOME in my book as always thanks for sharing with all my respect to you from Ont, CANADA. PS: how can I contact you or send you private message thankyou and cheeeeeeers.
Everything is based on vapor pressure in the tank/evap. It's funny how the type of "error" from the pressure sensor determines the failure code biased by the current command being executed. Sometimes, the terminology used is harder to figure out than the actual system
So since you were clogging the other port with your thumb (on the solenoid)-- Doesn't that mean that it has to be leaking from the casing somewhere? Maybe there was a crack or split in the clamshell that could have been spotted; most likely a split in one of the nipples on either side. Maybe someone pulled the hose off while changing spark plugs or something else, and ended up cracking the nipple at the base. I always love it when a job is straight forward like this-- you end up fixing it before any of the stress kicks in, and yet you still get that boost of accomplishment and dopamine on the back end. SUCCESS!
Apology accepted, I hope my boss will be as understanding when my terrets kicks in. GROUNDS, definitely a GROUND, gotta check the GROUNDS, ya, gotta watch Judge Wopner at 5:00.
Love the channel you really know your stuff and are great at explaining how you do things . I also live in Colorado and always am breaking down. So do work as a mechanic ? I always need a good mechanic?
When my purge went bad. After putting gas. My car won’t start after. I press on the pedal and got it to stay on and drove home close by. I removed purge valve u can blow thru it easily I replace it now working fine after putting gas. I still have large leak code p0455 I think is probably vapor canister vent solenoid
I would think this problem would manifest in OBD live data as consistently low negative pressure from the evap pid (inability to build vacuum) i guess i should have asked my younger self that question instead of cheating and using the google. Also parts changers and diagnosticians alike beware - make sure you get the correct part. On my 2008 hyundai oreilly had the wrong part in their system and sold me a binary purge valve, instead of a pwm controlled solenoid. The part will work for maybe as long as few months or so, or until the evap drive cycle tests are finally completed.
At 14:40 is there a rip in a rubber hose with the fatter/ring part on it? The hose coming from the battery so to speak going to the engine cover. I don't know how to explain it properly because I don't know what it's for but generally they don't come ripped from factory.
No rips in the hoses- I inspected before reassembling. always something to check for. also I leak tested the system using my Autel after the new one was installed and it passed.
Ohhhh I see what you mean. no no that’s just a foam rubber insulator over the actual plastic hose. I also thought the same at first. good eye though!!!
The techs that have attended our training classes on evaporative system diagnostics would have done 90% of the testing from the front seat of the car with the scan tool. They would not have shot gunned any parts. One of the first things we break down is what exactly a DTC is. The answer to that question is it is the identification number of a test that a computer has run that has failed. The next thing we work on is finding out how did the computer run the test in question and then we study and practice how we can test the exact same way that the computer does. This system as you realized does not use the pump to pressurize the cannister and fuel tank, Kia has gone away from DMTL and now is using a system that is exactly like GM and Ford. There are a number of manufacturers that have followed that same strategy. That of course means we can test every one of these cars the same way. With the incorrect purge flow code the testing would be with the engine idling, monitor the purge valve duty cycle and the fuel tank pressure sensor. With the vent valve open and no purge command the tank and cannister should be at atmospheric pressure. When the purge valve is commanded on, even with the vent valve open a very slight vacuum should appear in the fuel tank. With the purge valve turned off and closing the vent valve with bidirectional controls the fuel tank should remain at atmospheric pressure or should slightly start to rise in pressure. The one thing that it should NOT do is go into a vacuum. If you see the vacuum building, this is the first thing you would need to do outside of the car, disconnect the purge valve electrical connector. Open the vent valve to bleed any vacuum off of the tank and cannister and then command the vent valve closed again. If it goes into a vacuum again, then the purge valve is bad.
Yes I have a previous video where I do exactly this with the scantool, using the pressure sensor as my indicator. If I wasn't filing I would have used my AUtel and not even gone under the car.
@@SchrodingersBox I was wondering if that was the case. I obviously haven't seen the other video. I try to get techs to memorize the GM monitor, step by step and what code sets when a test fails. It's one of the few times I ever try and have them memorize something. Then once they know that one, they can adapt their testing routine as required to any system that is different. I tell them all the time, we can have them diagnosing 90% of evaporative emissions system problems in less than ten minutes even if there is more than one failure and rarely touch a smoke machine. We even have live broken cars that we have done in our online classes that the class works to figure out without touching the car.
I’ll see if I can find the leak but basically I used my autoenginuity where I close the vent solenoid with engine running and then draw from the purge and see that there is vacuum confirming vent closed. if the vacuum wasn’t there the vent must have failed to close. then I turn off the purge to “trap” the vacuum and look for decay. a rapid decay indicates the purge valve failed to seal. obviously also some other tests in between as well. but my Autel now has an auto-test that does all this in one simple button press.
@@SchrodingersBox This is the cliff notes of GM and Ford's evaporative test. 1. The test starts by purging vapors from the tank and cannister. 2. Large leak test closes the vent valve and opens the purge and attempts to reach approximately 8 inches of water vacuum. If it achieves the target vacuum the large leak test passes. 3. Small leak test measures the time for the vacuum to decay. This is where learning the variables that affect the decay rate is necessary. If it bleeds off too fast the small leak test fails, if it holds long enough then the test passes. 4. Then the PCM commands the vent valve open. The vacuum should immediately decay to atmosphere. 5. Next step is to turn the purge valve back on and remove any vapors that were produced. 6.Then turn the purge valve back off and the vent valve back on to test for incorrect purge. This is where the tank and cannister pull back into a vacuum if the purge valve is bad. To locate leaks all you need to do is command the test to run and start blocking off sections of the system. (The following is for when there are rubber hoses making the connections and not hard plastic lines) If the system cannot pull 8" of water vacuum and you pinch off the filler neck hose and now the vacuum increases, there is a leak in the filler neck area. If that doesn't get the vacuum to rise try clamping off the vent valve. If it still isn't rising try clamping both off. If that doesn't cause the vacuum to increase the tank, the cannister itself or the line between the purge valve and the cannister are in question. There is more to the routine such as the first check before the car is even started which is to use bi-directional command to operate the vent valve. If you can hear it close, then you can go into the above purge and seal test. If you cannot you have to prove that out first and if it is bad, clamp it off to allow for testing of the rest of the system.
@@SEXYTECH1000 It's something that a leaking purge valve can cause, but just because the car is hard to start after fueling doesn't mean that it is definitely bad.
Well, I could have diagnosed that fault in half the time... from my lawn chair no less, but that wasn't a bad effort for an amateur. At least, with all that blowing, you would have cleared out any spiders in the works. 🤣 And where can I get me one of those mini vacuum pumps?
I see your channel and you as a teacher, you seem to make way too many mistakes and you make way too many excuses for yourself when things don't go as planned. A major problem that RU-vidrs have is verbalizing every thought that enters their head, stop doing that please. Blow into the canister, and it's clear, move to the next step, no excuse needed. I should have done A, B, & C first, where is your checklist, your diagnostic chart that you can make from personal experience, no mistakes made unless you discover you need to create an update, no worries, it's normal. In my book, teachers are not allowed to make mistakes but they are allowed to make new discoveries and then annotate that discovery and never make that same mistake again. I know manufacturer flow charts suck, this is why we need to make our own, no mistakes made, time saved, no checks forgotten, and results found in the shortest amount of time even if some steps are redundant since we are not clairvoyant enough to go straight to the actual problem.
