F250 6.2 Strange Idle Stumble

[Bill-2020]

To the F250 6.2 gasser owners... I have a 2020 (6K miles) that has a strange "idle stumble" in the warm-up cycle (about 1/2 the way into the warming time), and then the same "idle stumble" after warming up, but not as pronounced as when it's warming up and beginning to idle down a bit. The stumble is like it almost has a misfire, but no codes are thrown. It doesn't do it so bad where it would seem as if it's trying to stall or anything, just as if its lost its timing or something for a split second. This was first noticed at about 1500 miles, but I had not stood by the side of the open engine bay during a warmup cycle or let it idle in park/neutral yet.

My idle sits just above the 500 RPM line on the dash (Low 600's according to the scan tool in live mode) while in park or neutral, no load. It idles smooth and then the "stumble happens for a second and then it's gone... then it comes back. Very repeatable without having to try.

If I'm in Drive, idle speed remains the same and the "stumble" is nearly gone. Also, no A/C on, no other heavy loads on the engine when this happens. Driving? Doesn't seem to do this at all. But it's subtle enough that at idle, I can feel it in the seat as the body of the truck wiggles just a bit, so when driving I'd never be able to tell the difference between rough road and idle stumble. When it happens the idle needle sometimes moves down ever so slightly then back up to where it was, but it's very slight.

I've changed fuel from non-tiered to top-tier gas, no change. I thought maybe I got some bad fuel so I dropped in a couple cans of Seafoam on a fill up recently and burned the tank down to empty with no changes. I tried a mid-grade octane tank of gas, no change either. I'm used to a smoother idle in a large V8. (Tundra 5.7, in know apples/oranges, but still...).

Is this a normal thing for this particular engine? I've checked for vacuum leaks, I hear nothing. I've scoured the web and multiple other Ford forums and what I find is those who complain about this have 10s of thousands of miles on them and a tune-up corrects the problem. But their idle problems are much, much worse than mine.

Ideas? Experience with this? A trip to the dealer for insight is next, but I wanted some opinions or knowledge of experience on this before heading to a dealer. My brother's 2020 doesn't exhibit the same stumble, for what its worth, but then again he's at altitude so things may be different.

(this 2020 6.2 engine is slightly different than previous years. The air filter is actually the same size and same air box as the 6.7 diesel, but no gauge on it and no prefilter. The mass air flow (MAF) is behind the throttle body instead of between the air box and the throttle body. Those are the only changes I've been able to see so far.)

[Ken / Claudia]

From a guy who has driven fleet vehicles for 39 years besides my own. Some days I might have been driving 4 or 5 different vehicles. Computers and sensors, they control everything. The dealer and a top tech is what you need to discuss this with. Likely nothing to be fixed or changed until it gives you an check engine light. I would not be concerned until it throws a code, even wait til route maintenance to talk about it without a code present. Once the check engine light comes on, scan it yourself. I do and then make a call.

[wiredgeorge]

Today's trucks are a shade on the complicated side and I am by no means a truck mechanic but I would check for a vacuum leak, an issue with the spark plugs, or a problem with the ignition coil. Is your truck throwing a CEL? If you can get to a shop with a Ford specific code reader it might be a good idea to start there first... I have several scanners but they won't catch some Ford specific codes. Seems your 6.2L isn't the only one with this issue. This was discussed on F150Forum.com (used to own an F150). Lots of discussion:
https://www.f150forum.com/f38/2010-5...313546/index3/

[travelin texans]

A 2020 with 6k miles should still be under warranty, that's where I'd be going with it.
There are some things best left to those with the know how & equipment to diagnose the problems. There are very knowledgeable folks on here, but unless one of them is one of the those Ford certified technicians taking any other advice could void that warranty.
The days of the shade tree mechanic are all but gone unless you've got all sorts of computers & electronic gizmos tied under that tree.

[chuckster57]

Originally Posted by travelin texans

A 2020 with 6k miles should still be under warranty, that's where I'd be going with it.
There are some things best left to those with the know how & equipment to diagnose the problems. There are very knowledgeable folks on here, but unless one of them is one of the those Ford certified technicians taking any other advice could void that warranty.
The days of the shade tree mechanic are all but gone unless you've got all sorts of computers & electronic gizmos tied under that tree.

You should see my shelves

I have bought more scan tools this last year because of TPMS and airbags. I have saved way more than the cost of the repair at a shop.

[Bill-2020]

Thanks, guys. No codes thrown. I've read those same threads and many more like it, George. Seems the only issues that arise are on different engines and much older to boot. Yes, a lot of the same troublesome parts can be on multiple engines so the effects and causes can be the same from a 5.0 to a 6.2.

I do all my own maintenance, always have, and I agree the dealer needs to give it a look so I'll make an appointment and leave it for them. They'll likely need it cold if they want to experience it when its warming and at its worst, so an overnight cold soak at their facility would be best. Last time I was left without my personal vehicle for any length of time due to mechanical was 1990. Guess its time huh.

I was curious if what I'm experiencing is something others have noticed as well. One individual I spoke to the other say said it almost sounds like engine lope (as they listened to it). I guess I could see how that could be, but typically that's something I remember hearing about on engines that are not electrically controlled (older designs and more of a muscle car thing).

[wiredgeorge]

Originally Posted by Bill-2020

Thanks, guys. No codes thrown. I've read those same threads and many more like it, George. Seems the only issues that arise are on different engines and much older to boot. Yes, a lot of the same troublesome parts can be on multiple engines so the effects and causes can be the same from a 5.0 to a 6.2.

I do all my own maintenance, always have, and I agree the dealer needs to give it a look so I'll make an appointment and leave it for them. They'll likely need it cold if they want to experience it when its warming and at its worst, so an overnight cold soak at their facility would be best. Last time I was left without my personal vehicle for any length of time due to mechanical was 1990. Guess its time huh.

I was curious if what I'm experiencing is something others have noticed as well. One individual I spoke to the other say said it almost sounds like engine lope (as they listened to it). I guess I could see how that could be, but typically that's something I remember hearing about on engines that are not electrically controlled (older designs and more of a muscle car thing).

Keep in mind the tech that scans your engine MUST use a scan tool that catches all Ford specific codes. The CEL codes are kind of generic/universal but there are codes that pop that will throw the wrench light and these are never picked up by a regular scanner. If you care to check it out, there is an open source tool called FORSCAN that you plug into your OBD2 port and it talks to your laptop and does read all Ford specific codes thrown.
http://vi.raptor.ebaydesc.com/ws/eBa...=1616519974848

It isn't a bad idea to use a Ford certified tech but it is nice to be armed with some info going in so you can judge if the tech is top notch or a dud.

[jasin1]

Originally Posted by Bill-2020

To the F250 6.2 gasser owners... I have a 2020 (6K miles) that has a strange "idle stumble" in the warm-up cycle (about 1/2 the way into the warming time), and then the same "idle stumble" after warming up, but not as pronounced as when it's warming up and beginning to idle down a bit. The stumble is like it almost has a misfire, but no codes are thrown. It doesn't do it so bad where it would seem as if it's trying to stall or anything, just as if its lost its timing or something for a split second. This was first noticed at about 1500 miles, but I had not stood by the side of the open engine bay during a warmup cycle or let it idle in park/neutral yet.

My idle sits just above the 500 RPM line on the dash (Low 600's according to the scan tool in live mode) while in park or neutral, no load. It idles smooth and then the "stumble happens for a second and then it's gone... then it comes back. Very repeatable without having to try.

If I'm in Drive, idle speed remains the same and the "stumble" is nearly gone. Also, no A/C on, no other heavy loads on the engine when this happens. Driving? Doesn't seem to do this at all. But it's subtle enough that at idle, I can feel it in the seat as the body of the truck wiggles just a bit, so when driving I'd never be able to tell the difference between rough road and idle stumble. When it happens the idle needle sometimes moves down ever so slightly then back up to where it was, but it's very slight.

I've changed fuel from non-tiered to top-tier gas, no change. I thought maybe I got some bad fuel so I dropped in a couple cans of Seafoam on a fill up recently and burned the tank down to empty with no changes. I tried a mid-grade octane tank of gas, no change either. I'm used to a smoother idle in a large V8. (Tundra 5.7, in know apples/oranges, but still...).

Is this a normal thing for this particular engine? I've checked for vacuum leaks, I hear nothing. I've scoured the web and multiple other Ford forums and what I find is those who complain about this have 10s of thousands of miles on them and a tune-up corrects the problem. But their idle problems are much, much worse than mine.

Ideas? Experience with this? A trip to the dealer for insight is next, but I wanted some opinions or knowledge of experience on this before heading to a dealer. My brother's 2020 doesn't exhibit the same stumble, for what its worth, but then again he's at altitude so things may be different.

(this 2020 6.2 engine is slightly different than previous years. The air filter is actually the same size and same air box as the 6.7 diesel, but no gauge on it and no prefilter. The mass air flow (MAF) is behind the throttle body instead of between the air box and the throttle body. Those are the only changes I've been able to see so far.)

I had a completely different truck.. 2012 ram 6.7 diesel ..but it had a similar issue ..no codes ..idle stumble/ miss occasionally ...traced it to the electric fan clutch.. it only happens when the clutch is engaged...when you first start it up the engine is cold and doesn’t need that fan engaged until the engine warms up ...when it’s driving it doesn’t need it most of the time...but when it needs the extra cooling it would engage and some of the time it was causing a voltage drop for a millisecond and I would get the miss...not sure if you have a electric fan clutch but worth looking at

[Bill-2020]

Originally Posted by wiredgeorge

Keep in mind the tech that scans your engine MUST use a scan tool that catches all Ford specific codes. The CEL codes are kind of generic/universal but there are codes that pop that will throw the wrench light and these are never picked up by a regular scanner. If you care to check it out, there is an open source tool called FORSCAN that you plug into your OBD2 port and it talks to your laptop and does read all Ford specific codes thrown.
http://vi.raptor.ebaydesc.com/ws/eBa...=1616519974848

It isn't a bad idea to use a Ford certified tech but it is nice to be armed with some info going in so you can judge if the tech is top notch or a dud.

Funny you mention this George, I already have the FORSCAN (bought a year subscription) and the USB to OBDII adapter ( https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 )

I had thought about using that instead of my Actron scan tool to see if there was anything "deeper" to see but have not yet. I was hoping I just had some bad fuel or something that would work itself out. I had a dud of a Nissan tech once on the DW's car and an A/C related problem. I knew what the issue was, I replaced the components and then took it in to them to recharge the system properly. The tech instantly told me that I needed a new core because its leaking and there are trace amounts of refrigerant under the condenser drain. I told them "just charge the system, I'm trading it in." I knew that what he saw was from my work replacing seals at the firewall, not a bad core. Dud isn't the work I used.

Jasin1 - I'll look at that. I don't recall if the clutch was engaged or not. The good thing is, it's repeatable so the tech won't be able to tell me they couldn't make it happen. Just two things need to happen. 1. Turn it on 2. wait a few minutes parked (warning or hot).

[Ken / Claudia]

Post #8 regarding the fan clutch brings me back to saying Computers and sensors. There are things I doubt many of us even know what is being adjusted all the time. Some of those things being adjusted, turned on/off by the sensors and computers on their own. Can and do change the engine idle or RPMs not us.
Heck, without knowing much about that engine or been in a vehicle with one yet. A simple little thing as the automatic climate control adjusting makes noises throughout the system, I know in my current 3 vehicles in driveway all have that feature.
Wife wants cold on her side with heated seat on. I want warm air on my side with seat cooler on. In cold temps I leave the defrost or windshield mode on and the causing the A/C compressor to go on/off automatically. She has asked several times why the water is dripping under the vehicle or the noise and RPM change just from that.
I hope the OPs vehicle is just doing what it's supposed to do and he will get an answer and tells us what it was.

[Bill-2020]

Originally Posted by Ken / Claudia

Post #8 regarding the fan clutch brings me back to saying Computers and sensors. There are things I doubt many of us even know what is being adjusted all the time. Some of those things being adjusted, turned on/off by the sensors and computers on their own. Can and do change the engine idle or RPMs not us.
Heck, without knowing much about that engine or been in a vehicle with one yet. A simple little thing as the automatic climate control adjusting makes noises throughout the system, I know in my current 3 vehicles in driveway all have that feature.
Wife wants cold on her side with heated seat on. I want warm air on my side with seat cooler on. In cold temps I leave the defrost or windshield mode on and the causing the A/C compressor to go on/off automatically. She has asked several times why the water is dripping under the vehicle or the noise and RPM change just from that.
I hope the OPs vehicle is just doing what it's supposed to do and he will get an answer and tells us what it was.

I hope it is doing what it's supposed to also! If it is, it's something I'll have to learn to deal with, but it won't be easy. I'm not used to an engine running this way. I'd like to go find a new one on the lot, get the keys and let it warm up and see for myself if the stumble/shake happens on that one too. My pea brain says, "shoulda bought the 7.3 dummy!!" Others here will say "Ya should have bought the 6.7 diesel", and if it wasn't another $8-10K I would have!

As far as climate control, this happens with it off as well. Also does when the A/C is on but not as pronounced. The engine needs to have no additional load on it for this to be very obvious.

Just now I also thought, maybe the gas cap is not allowing enough air into the tank while at a low idle (malfunctioning valve in the cap), almost starving the engine a little until enough vacuum is created in the tank where the valve opens enough to begin to equalize, allowing fuel to flow better but then starts to create a vacuum again, causing the starvation - thus creating this stumble that comes and goes, yet fairly frequently, but give it some load (speed, A/C, in drive) and the fuel pump then pumps faster/harder and its just enough to overcome the faulty cap valve. I'll have to go see later.

At any rate, yes I'll let you all know what comes of this. Good, bad or otherwise.

[JRTJH]

There was a time when engines had carburetors, fast idle cams, acceleration pumps, chokes and jets to adjust the mixture. Those days are long gone for the automotive industry and fast becoming dinosaurs even in the small engine world. Check out the latest Stihl chainsaws, "electronic control"....

Anyway, with EPA doing what they do and the automotive emissions controls being what they are, everything has changed from the "old style" push the accelerator to the floor, slowly release it (to set the fast idle and choke) and start the engine. It'll stay in fast idle until you "tap the accelerator"... Back then, if the engine "skipped at bit during warmup" you could set the choke a tad richer, increase the fast idle cam setting, retard the timing a touch or sometimes, just tighten the air cleaner cover after wiggling it a bit on the carb mount..... Those days are long gone... Now the computer won't let you make any adjustments to parts that are no longer even used.

Today's "comupter managed engines" are designed to run at the lowest RPM, leanest fuel settings and greatest timing advance without engine damage... Note, that's NOT the same as the "nicest setting for smooth operation"....

I'm certainly no expert, but I'd suspect that the way your engine is operating is "within the normal engine specifications" (the +/- range) and Ford will probably suggest there's nothing out of tolerance so no warranty repair...

Possibly, there's an "engine management software update" ??? Otherwise, I'd suspect it's more a situation where your specific truck was "built with two or more components that are within the +/- specs on the low end and when those two components are "in a matched set" the computer management "magnifies their specific minus end (or positive end) of the tolerance band" and the result is a "one second skip during warmup" and only occurs when the computer senses the output of the "first low end tolerance component" when compared to the "second low end tolerance component".... It's all part of that "lowest possible fossil fuel burn" computer program.

[wiredgeorge]

The biggest mistake a person can make with a yet to be diagnosed engine issue is to start throwing parts at it. Run your FORSCAN tool and see if it is dropping any codes prior to the shop mechanic going at it. The easiest thing for a shop to say is that it is supposed to have an erratic idle as that is they way it was designed. Do challenge them to cold starting another 6.2L and let them see if it also has the same cold start characteristics.

[flybouy]

JMHO but I won't touch a vehicle while under warranty. I'll have the dealer even do the oil changes, which are about the same cost as doing it myself. Why? Because if anything goes wrong THEY are the ONLY people that have touched it. There's no arguments or finger pointing. Once it's out of warranty it only goes to the dealer for oil changes. These days EVERYTHING is interconnected I've been doing this for 30+ years and have never had a warranty claim issue. YMMV

[wiredgeorge]

Running a scanner isn't going to void the warranty. It would be better to be armed with this info prior to the dealer trip.

[flybouy]

Originally Posted by wiredgeorge

Running a scanner isn't going to void the warranty. It would be better to be armed with this info prior to the dealer trip.

Of course not, but that's different than you're statement about "throwing parts at it".

[jasin1]

Have you replaced your air filter? Or did you have to remove it for adding accessories and reinstall it? ...My MIL took her ncarbto Walmart to get an oil change nd they talked her into changing every filter..they didn’t reinstall the air filter tube correctly and she got about a mile away and it started missing pretty bad...I found the connection was loose and the mass air flow sensor was getting a improper reading...causes the fuel mixture to be wrong..

I agree I would just take it to the dealer after I scanned it but i would also look for obvious problems just to save the hassle

I just like figuring things out

[jasin1]

Originally Posted by jasin1

Have you replaced your air filter? Or did you have to remove it for adding accessories and reinstall it? ...My MIL took her ncarbto Walmart to get an oil change nd they talked her into changing every filter..they didn’t reinstall the air filter tube correctly and she got about a mile away and it started missing pretty bad...I found the connection was loose and the mass air flow sensor was getting a improper reading...causes the fuel mixture to be wrong..

I agree I would just take it to the dealer after I scanned it but i would also look for obvious problems just to save the hassle

I just like figuring things out

Found this just now..apparent problem with mass air flow sensor ..similar symptoms

[Bill-2020]

Gas cap off made no difference at all for the half minute I let idle like that. (That one was really grasping at straws anyway.)

George - No DTCs to speak of on FORscan. All 20 modules are free from Covid.

John - I agree, there's a lot going on in today's advanced engines and the many systems. And I hope it's just "doing its thing" and there's no worries except for who's gonna get the ladder out next and wash the roof?!! Me or the DW... Me.

Marshall - I understand where you're coming from. I do my own oil changes, I like to know it's done right. Anything that's under warranty I'll let them handle, especially if it's more than I care to dive in to. I watched a Toyota dealership oil change center pour some 6+ quarts of oil through my 4runner once. They forgot to reinstall the drain plug. I had to show the guy what he didn't do before he attempted to start it. Sure, I could have yelled to him on quart #1, but I wanted to see how many he'd go through before the realization kicked in. From that day on, I do my own.

Jasin1 - Yes, I changed the air filter to a different one and the intake is all back the way it should be. But that was done after this issue was first noticed at about 1500 miles (only because I had not let it idle while I stood next to it yet). Side Note: This 6.2 has the same air box and filter as the 6.7 diesel, but if you search for air filters Ford and others (aftermarket) return the 2019 and prior part numbers. MAF sensor is located behind the throttle body, not in front near, or half way up, from the air box. That's a first for me, never seen a MAF behind the throttle body. But then again, I've been buying and driving Toyotas and the DWs Nissans and Hyundais for the last 30+ years.

I'll call the dealer, make an appointment and challenge them and their knowledge on a proven engine. Hopefully they have a 6.2 on the lot to cold start. Pickings have been slim lately. Most super dutys here go right to the fleet buyers I'm told.

[wiredgeorge]

Originally Posted by flybouy

Of course not, but that's different than you're statement about "throwing parts at it".

I mentioned to Bill not to throw parts at the issue until it was successfully diagnosed. Then buy the parts needed. My statement stands and is solid advice.