So recently bought a 99 f250 v10, not new to the platform at all but beating my head against the wall trying to figure out what's going on. Truck has bad shudder shaking when accelerating at times, there's times it runs great (seems to shudder more when lower on gas which id think possible pump except its only an issue under about 1800 rpms). It idles amazing 100 percent of the time provided its in park. Occasionally when at a stop light in gear on brakes it'll stumble a bit. It feels like torque converter shudder but it always shifts fine although possibly a little slower than my last v10 which was an 02. Previous owner put brand new edelbrock coils on it which im not crazy about (they're roughly 3 months old) and I believe ngk plugs, I disagreed with both and argued he should run motorcraft. I have no engine lights or codes currently. I had egr flow insufficient flow previously (first v10 ive been around that actually had the garbage), but cat was plugged. Fixed cat issue and ran seafoam through tank and a can of emissions cleaner (dont remember exactly what it was specifically atm) through intake and replaced fuel and air filter and cleaned maf. All of which improvedits performance slightly but noticeably and removed engine codes from the situation (i.e. no light and no codes). Iac was also replaced recently. So where im at now it recently downshifted and shifted back up a couple times maintaining about 70 mph without any throttle movement ( according to my wife 🙄 I drive truck and was out of state) so im not sure where to go from here, truck has just under 150k miles and I've never had issues with 4r100s behind a v10 until over 250k and almost always fixed with trans filter and fluid change. Truck sat for a few years before previous owner bought it. Im leaning towards blaming coils and/or plugs before thinking torque converter shudder (trans fluid also looks/smells pristine at least on dipstick). Idk what to do currently, in a position where I can't throw tons of money at it, any ideas recommendations would be greatly appreciated!

 

nothing wrong with those coils, very companionable with OEM , 4r100's i have rb'd way to many that never reached 75k , how long a trans lasts depends on the driver, as to the shudder you state it sat for some time,i'd be looking more at sticky/gummed injectors,

 

Yeah, injectors like @charlie g said and:

How old and/or discharged and/of low quality is the battery? They'll do weird things with shifting if the battery is low or if grounding is bad.

 

Appreciate the input guys, will be replacing battery before too long for now im going to leave injectors alone until I put tires on it and can give it the old Italian tune-up. after roughly 200 miles of driving got egr flow insufficient code again so going to start with dpfe and pull egr valve and tube and clean them. Hopefully it will solve the problem, ill check in after either way.

 

I know I took awhile, spent time scratching my head and then ignoring problem, finally started to get misfires at idle and got excited. Turns out the edlebrock coils were failing at less than a year old so replaced them with motorcraft and did plugs. Runs like a new truck!

 

Interesting!

Generally new coils from about any reputable name solve misfires like yours and I would have looked there first, but Edelbrock is a reputable name and three months is pretty new so I moved on. I wonder where Edelbrock sources their coils.

 

all the reviews I read on the edelbrock coils for triton motors are bad, even the parts house told me in their training they're told specifically about ignition parts that they're designed for race/show cars and not for daily drivers, which my take away was they cheap out on them lol

 

Coils fixed the misfire or the shudder or both?

The shudder sounds like a torque converter and mine is doing the same thing. At least that's what I am going with on my 02. Mine seems like the classic TC symptoms: when it acts up, it takes more revs to get going from a stop light if uphill, shudders around 35-40mph once warmed up, 35-40mph seems to be the speed that triggers it, if I strictly get on the highway, it's fine, but those long around town grocery trips get annoying, etc. So that's for sure not coils in my case and a little easier diagnosis. I hope. I was going to swap it out this weekend, but some other parts didn't arrive in time, so it's next weekend for me.

About 280K on mine, so I guess that's a decent life for a TC. If your shudder comes back, let us know. Or if anyone reading has an opinion that counters my diagnosis on mine, I'm interested.

 

It fixed both drove like a new truck. Took several weeks for it to finally start misfiring at idle, before that it was only under load and shook the hell outta you. It felt very much like torque converter shudder, except trans was shifting ok just felt slower than normal if I turned off overdrive it got slightly better ( almost completely stopped shaking at first) but was the worst taking off from stop and maintaining speed uphill.

 

Best thought I have is pay attention to its shifts, mine seemed to take way longer to shift but didn't feel any slipping just longer gap in between gears. If you feel it lock into gear after shifting and no slip it could be coils as was mine. My last v10 which was 02 as well a friend of mine has now and pushing 300k on original trans and converter and it still shows up for work every day and shifts fine, only issue is ever had out of that trans was about 200k it started falling into neutral going down highway and slipping occasionally. I did trans fluid and filter change and that solved it. Im not saying you're wrong in what you're thinking just sharing my experience

 

These things really love a fluid change. Every time I have done that, the engine runs so much smoother from not having to work as hard. You don't really notice it until you miss an interval and wonder why you can't hear the engine at idle after you finally change it. I'm going to monitor mine closely this week, but I am still leaning towards TC here. No misfires. When it acts up, it takes a lot of revs to get going from a light, but shifting and everything after that is smooth as normal except the shudder at 35-40. When it is not acting up, everything is normal. That's always pointed to TC for me.

Thanks for the feedback. Glad those coils fixed yours, that's a much easier fix

 

That's too bad. I normally stick with normal brands like Delphi or Bosch, but good to know on these!