2019 Backfire issue?

[5280tunage]

Hey all, hoping some folks can come up with some good ideas here. Over the last 2 months or so, this issue has crept up virtually every time I fill up. It ONLY happens when I fill up and it happens within one or two minutes after filling up, and within less than a mile of driving. So for those of you that may not know my mods, I have SPD turbo adapters, SPD downpipes, full custom exhaust, O2 spacers for the cats (I did not do the cat delete), CAI, Mishimoto intercooler, Plugs with less than 10K on them (the Ruthinium plugs, properly gapped), and a 5star 91 tune to match the upgrades.

So this has happened probably 80% of the time over the last 2 months or so, whenever I fill up, as I'm leaving the gas station, after light acceleration and letting off the throttle, I get a backfire. It literally feels/sounds like I drove over a plastic bottle each time and I can lightly feel it in the chassis. I'm running the exact same setup, exact same tune, that I've had for 2 years. Nothing else has changed. The only thing I can think of is that about 3 months or so ago, I ran a can of SeaFoam through the fuel system, but that's it. I don't like this and I'm concerned it may damage something major over time, any thoughts on what I could/should do, or what might be causing this. Again, I can't stress this enough, I can drive 200 miles with no issues, but if I fill up, and drive away, there's a good chance I will get a backfire, and only one, never more than one.

thanks in advance, oh, and absolutely no CEL's or warnings from the vehicle at all. No loss of power, no stuttering, just a crazy loud backfire.

And I did find this thread, but there really never was a resolution or outcome. https://www.expeditionforum.com/threads/engine-backfire.51994/

 

[SyndicateZ]

evap canister

Also dont overfill the tank ( stop pumping once it click)

 

[GlennSullivan]

Is it possible that there is an issue with the evap system that is related to what is going on? Is it absorbing too much fuel vapor during refueling process and sending it to the engine upon restart, which is causing the backfire?

I would go a step further than suggested above and try fueling to only 3/4 of a tank. If the problem goes away, check all evap system components, replacing as necessary and then slowly increase the fill level.

 

[GlennSullivan]

Is it possible that there is an issue with the evap system that is related to what is going on? Is it absorbing too much fuel vapor during refueling process and sending it to the engine upon restart, which is causing the backfire?

I would go a step further than suggested above and try fueling to only 3/4 of a tank. If the problem goes away, check all evap system components, replacing as necessary and then slowly increase the fill level.

The more I look into it, the more I think is is a bad EVAP purge valve, which, if working correctly, should slowly (over time and after warmup) release fuel vapors collected in the charcoal canister during refueling back to the engine to be burned. If malfunctioning or stuck open, it could, upon startup, immediately release all fuel vapors collected during refueling to be burned - backfire.

What I do not understand is why the vehicle is not throwing any codes.

 

[5280tunage]

I agree @GlennSullivan , I would think any sort of fuel system issue would be throwing codes but I haven't had a single CEL. The real trouble too is I can't even take it in to get something like this fixed under warranty without codes, telling the dealer service teams that I'm getting a backfire, and only when filling will be pretty hard to replicate and I'm sure they won't do anything without the codes.

I typically always stop filling when the pump stops, but I will pay attention to that more.

From the looks of it, the evap canister on these is close to $300 so I would definitely want that done under warranty if it truly needs it. Also means I need to basically remove my tune, since that clears any codes, which I don't want to happen if it actually does throw a code.

 

[99WhiteC5Coupe]

When an evaporative system solenoid fails - two things can happen.

If it sticks “open” - it will allow excess fuel vapors into the intake at startup, usually resulting is a rough idle or engine stall. It is possible to cause an engine backfire.

If it sticks “shut” - it will not allow excess fuel vapors into the intake when designed, and eventually “load-up” the charcoal canister, ruining it.

 

[5280tunage]

so from what i can tell, there are two solenoids, a purge and a vent. The purge looks to be on backorder, while the vent seems to be available, and is roughly $30, I'd be open to replacing that if the job isn't too hard, I have no idea where that is to be honest.

I would still think that if a solenoid was stuck open or closed, it would fire off a CEL wouldn't it?

 

[GlennSullivan]

I agree @GlennSullivan , I would think any sort of fuel system issue would be throwing codes but I haven't had a single CEL. The real trouble too is I can't even take it in to get something like this fixed under warranty without codes, telling the dealer service teams that I'm getting a backfire, and only when filling will be pretty hard to replicate and I'm sure they won't do anything without the codes.

I typically always stop filling when the pump stops, but I will pay attention to that more.

From the looks of it, the evap canister on these is close to $300 so I would definitely want that done under warranty if it truly needs it. Also means I need to basically remove my tune, since that clears any codes, which I don't want to happen if it actually does throw a code.

I'm certainly confused why you are not getting any CELs. If for no other reason the backfires should be picked up by the knock or misfire sensors and should set a CEL as detonation or misfire.

99WhiteC5Coupe mentions 2 possible scenarios, copied below. I would thing that #1 is certainly a possibility, It can be stuck open and for some reason the ECU can't sense the fault or the tune is preventing the ECU from setting the code.

I would also suggest a third possibility, which is according to "normal system operation" after fueling the valve is not supposed to open until the vehicle comes up to temp and then only to gradually feed vapors back into the combustion cycle. Is it possible that you tune could be inadvertently causing some misfunction to the valve / system where it is opening the valve right after restart?

If it sticks “open” - it will allow excess fuel vapors into the intake at startup, usually resulting is a rough idle or engine stall. It is possible to cause an engine backfire.

If it sticks “shut” - it will not allow excess fuel vapors into the intake when designed, and eventually “load-up” the charcoal canister, ruining it.

Also
With the Mods that you have described, I would suspect that the Dealer and / or Ford will blame whatever is happening as caused by the mods and not cover any of this under warranty.

 

[5280tunage]

@GlennSullivan Couple things, I will remove the tune and see what happens next fill up. But again, I've been running the tunes and mods for years and this is just now starting to happen. Which solenoid are we talking about, as I see two possible evap solenoids.

And I hear you on the mods and warranty, but I'll fight that, I haven't done anything to fuel system, I don't see how a cat back exhaust, ypipes, or adapters could possibly impact the fuel system in a way to create a backfire.

 

[GlennSullivan]

@GlennSullivan Couple things, I will remove the tune and see what happens next fill up. But again, I've been running the tunes and mods for years and this is just now starting to happen. Which solenoid are we talking about, as I see two possible evap solenoids.

And I hear you on the mods and warranty, but I'll fight that, I haven't done anything to fuel system, I don't see how a cat back exhaust, ypipes, or adapters could possibly impact the fuel system in a way to create a backfire.

I think putting stock tune back in may tell us some things at least with CELs

Everything I see says it is a failed Purge Valve which controls the vapor movement from the collection canister at the fuel tank to the intake. It would make sense that this was working all along and has just failed and that is the reason the backfiring just started happening.

This is also evidently a very common part failure after Ford changed the design in the early 2010's. Again what is strange is that in all cases there are multiple codes thrown when this happens, so something is keeping your ECU from either knowing about the failure or reporting on the codes.

The Purge valve is located somewhere under the hood near the intake (I don't have a Gen 4 so can't tell you where). The Charcoal Canister is located adjacent to the fuel tank and the canister vent solenoid is attached to the canister. But I would focus on the purge valve/

Here is a video that shows how to test the valve, it is for an older car but evidently the valve has not changed. https://www.youtube.com/watch?v=S6dsQoq73aE

You are preaching to the choir about the warranty denials, I'm just reiterating what I'm seeing with other people in the same situation and Ford is the worst out of any of them on denials. They have hosed me on some stuff that should clearly have been covered and my truck is bone stock.

 

[5280tunage]

Interesting, found this as well, seems to be more than just a corner case. https://www.fordraptorforum.com/threads/exhaust-backfire.67699/

But annoyingly, these stupid valves are far more expensive than the other one of course. And it appears to be back ordered a lot of places, of course. I did find a non-oem part on amazon for like 20% of the price, but that always scares me. Guess I should try that troubleshooting technique in that super helpful video, thanks for sending that along.

 

[GlennSullivan]

Interesting, found this as well, seems to be more than just a corner case. https://www.fordraptorforum.com/threads/exhaust-backfire.67699/

But annoyingly, these stupid valves are far more expensive than the other one of course. And it appears to be back ordered a lot of places, of course. I did find a non-oem part on amazon for like 20% of the price, but that always scares me. Guess I should try that troubleshooting technique in that super helpful video, thanks for sending that along.

HeHe, yeah that is what happens when a vendor has massive failures on a part, they can't make replacements fast enough.

Rockauto Has Them For $70.00, but before you order one, why don't you confirm that is the part needed, Do the test and make sure you plug the tube that leads from the valve to the intake so you don't get a huge vacuum leak. See if the problem goes away, if it does, buy 1 of them from Rockauto and backorder one from Tasca parts to keep as a spare for next time it fails.


Looks like the people on the FordRaptorForum site don't seem very concerned. I guess they care less than you are about turning their plastic intake manifolds into tiny little pieces.

 

[Soliyou]

Interesting, found this as well, seems to be more than just a corner case. https://www.fordraptorforum.com/threads/exhaust-backfire.67699/

But annoyingly, these stupid valves are far more expensive than the other one of course. And it appears to be back ordered a lot of places, of course. I did find a non-oem part on amazon for like 20% of the price, but that always scares me. Guess I should try that troubleshooting technique in that super helpful video, thanks for sending that along.

You need to install forscan. It will allow you to do active tests on EVAP system components. You can monitor valve operation and switch them on/off to troubleshoot the problem.

 

[5280tunage]

You need to install forscan. It will allow you to do active tests on EVAP system components. You can monitor valve operation and switch them on/off to troubleshoot the problem.

awesome, I have forscan already so I will see if i can try this. But i'm curious how an electronic test would tell me anything more, given that we all agree if the valve is stuck open, that it really should be throwing codes. I think that's why in the video they recommend the physical leak check. I grabbed a flashlight last night and looked around the throttle body area, couldn't find this valve, I wonder if it's under the engine cover. Thanks for the idea!

 

[GlennSullivan]

Found an F150 and Ford Van videos which show the location on the drivers side at the middle to rear rear of the engine under the cover. No matter the vehicle / model They all seem to be adjacent to the intake manifold so the cover needs to come off in any case.

This pic shows a new part sitting on top and to the left of the existing installed part. Also looks like a PITA to access the electrical connection, which faces the firewall, that is if the Expy has it in the same location.

The mechanical test starts with the engine cold and off. Unplug the electrical connection and the hose coming from the canister, put your finger over the now bare valve port and have someone start the engine. If you feel any suction the valve is mechanically stuck in the open position. Note that this is a "normally closed device - when unpowered it should be closed and then powered to open. If you feel suction the valve is bad.

If you are not feeling any suction, next test electrically. Shut off the engine, reconnect the control pigtail, finger back on bare port, restart engine, if feeling suction, the problem is electrical as the system should not open the purge valve until the engine is fully up to temperature.

Ford Ecoboost 3.5 Purge Valve Issue: Should You Replace It?

(DTC) P0496, P0456, P0455, P04F0, and/or P0451 all may be signs your evaporative purge valve is leaking signs your purge valve is leaking is struggle to star...

www.youtube.com

f150 ecoboost purge valve

How to replace the purge valve on a 2017 F150 3.5L ecoboost engine

www.youtube.com

 

[5280tunage]

Thanks @GlennSullivan, I'm going to go the route of using a vacuum gauge to test, regardless I've ordered a new valve anyways, seems they are likely to fail. And this is one of those things, i'm sure it would be covered by the warranty but then I have to deal with the pain of a dealership and waiting, and waiting, and no loaners, and etc. I'll use the gauge as I'm honestly too embarrassed to ask the wife to start the vehicle while I'm testing, I'm just embarrassed with the number of issues I've had over the years, large or small.

 

[GlennSullivan]

Oh there you go getting all professional on me using a "Gauge" LOL. Good luck with the fix.