Misfire or rough idle on the 1999 Ford F-250
When misfire or rough idle gets reported
Owners of the 1999 Ford F-250 report misfire or rough idle at a median of 95,000 miles. A quarter of the reports come in before 80,000 miles and a quarter after 140,000 miles, from 22 reports that carried an odometer reading.
A part like this is normally expected to survive 92,000 miles. It is the 8th most-reported problem on this model year.
The mileage distribution
The reported range runs from 65,000 miles at the tenth percentile to 145,000 miles at the ninetieth, a spread of 81,566 miles across the middle 80% of reports.
A spread this wide points at use rather than design. Towing, climate, service history and city mileage all move a failure like this, so the median is a weak guide to any individual car.
5% of the dated reports were filed under 36,000 miles.
The whole distribution
| 10th | 25th | Median | 75th | 90th |
|---|---|---|---|---|
| 65,109 miles | 82,000 miles | 95,500 miles | 139,125 miles | 146,675 miles |
Read the 10th percentile as “one report in ten arrived this early”. Exact figures are shown in this table because it is the table of record; everywhere else on the site they are rounded to the precision the sample can carry.
What a percentile can and cannot tell you here
These five numbers describe the readings owners gave, in order. The median is the middle one: half the reports arrived below it. The 10th and 90th are the edges of the bulk of the distribution, and the distance between them is the part worth reading. A tight spread — say 70,000 to 95,000 miles — points at something that wears out on a schedule, and the schedule is knowable. A wide one, 20,000 to 190,000, points at a fault that hits some cars and never troubles others, which means the mileage on the listing in front of you tells you very little about your odds.
What these figures are not is a survival curve. Every reading here comes from a car whose owner filed a complaint, so the sample contains only failures: it cannot say what share of the fleet made it past 150,000 miles untouched, because those owners had nothing to report. Nor is the mileage the moment of failure — it is the odometer reading as recalled at the time of filing, which may be weeks later and is sometimes rounded to the nearest ten thousand by the person typing it.
Percentiles are shown at all only once 8 readings exist for the vehicle and mode. Below that the middle of a handful of numbers is noise wearing a decimal point, so the figures are withheld rather than dressed up.
What happens, and what it costs
Putting it right typically runs $250–$1,600 at an independent US shop. That range is an editorial estimate held in this site's failure-mode catalogue, not a figure from NHTSA, and it is a repair cost rather than a diagnosis cost.
The same failure on other years
The same failure is reported on 10 model years of this car. It shows up earliest on the 2005, at a median of 60,000 miles, and latest on the 2004 at 155,000 miles.
By volume the 1999 is the worst of them, which makes this a problem of this specific year rather than of the model as a whole.
If one year stands out to the left, that is the year to avoid; if the whole line sits at a similar mileage, this is wear rather than a defect in one production run.
Tick median reported mileage Solid middle half of reports Faint 10th to 90th percentile Colour how bad the failure is when it happens
What owners wrote
Verbatim from NHTSA complaint narratives, trimmed for length. The mileage is the one the owner gave.
Spark plug in the #7 cylinder suddenly blew out, ford comments were that they were sympathetic, but that the cost of repair would be born by me($3000.00). After doing some internet research I find this seems to be a problem with many others who utilize the 5.4 liter engine, even the dealer acknowledges he has had several cases. These were factory installed original plugs. *ph *nlm **dimsii ivoq entry posted after 12/12/02 cut over to artemis**768315
While driving 25 MPH spark plug disconnected from the engine, causing vehicle to stall. Consumer managed to pull over, and had the vehicle towed. Dealership was notified, but did not resolve the problem.*ak
Driving down the road, I heard this loud pop sound. Immediately following, were multiple popping sounds, so I pulled into the immediate parking lot on my right to take a look. Upon examining the engine, I discovered that the 3rd spark plug was blown out. Had to get a ride to napa to get more spark plugs. After several attempts at trying to replace it (being the mechanically inclined person that I am) I realize that I had a bigger problem on my hands. The threads are shot and will now have to have my vehicle towed to a nearby facility for repairs that are estimated between $1500 to $2000 (conservatively).*ak
Also reported on the 1999 Ford F-250
Other wheel or tire problem
ABS module or sensor failure
Other powertrain problem
Other engine problem
Tire blowout or tread separation
Premature brake pad or rotor wear
How far this goes
Complaints are voluntary, so 26 is a floor and not a count of affected cars. Mileages are typed in by owners and cluster on round numbers. And the mode itself is assigned by software reading the complaint text, which is reliable in bulk and fallible one report at a time.
Questions this page answers
At what mileage does misfire or rough idle happen on the 1999 Ford F-250?
Across 22 owner reports that included an odometer reading, half were filed by 95,000 miles. A quarter were filed before 80,000 miles and a quarter after 140,000 miles. These are the mileages owners reported when they complained, not a prediction for any individual car.
How common is misfire or rough idle on the 1999 Ford F-250?
26 reports have been filed with NHTSA, about 0.1 per 1,000 vehicles. Complaints are voluntary, so this is a floor rather than a count of affected cars.
What this is and is not. These are the mileages at which owners chose to complain to a federal agency, which is not the same as the mileage at which the part fails on every car. It skews toward failures that happened outside warranty, cost real money, or frightened someone. It is still the only public dataset that carries failure mileage at all, and the shape of a few hundred readings is informative even when a single one is not. Methodology · JSON · this failure on other cars
Source Owner complaints and recall records published by the US National Highway Traffic Safety Administration, model years 1996–2027 Figures rebuilt Published by AtWhatMileage How every figure is computed