Misfire or rough idle on the 1998 Cadillac Deville
When misfire or rough idle gets reported
Owners of the 1998 Cadillac Deville report misfire or rough idle at a median of 10,000 miles. A quarter of the reports come in before 10,000 miles and a quarter after 10,000 miles, from 8 reports that carried an odometer reading.
A part like this is normally expected to survive 92,000 miles. It is the 4th most-reported problem on this model year.
The mileage distribution
The reported range runs from 10,000 miles at the tenth percentile to 45,000 miles at the ninetieth, a spread of 36,000 miles across the middle 80% of reports.
A window that narrow is the signature of a part that fails on its own schedule rather than on how the car is driven — which is usually a design or supplier problem rather than wear and tear.
88% of the dated reports were filed under 36,000 miles.
The whole distribution
| 10th | 25th | Median | 75th | 90th |
|---|---|---|---|---|
| 10,000 miles | 10,000 miles | 10,000 miles | 10,000 miles | 46,000 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 3 model years of this car. It shows up earliest on the 1998, at a median of 10,000 miles, and latest on the 2001 at 140,000 miles.
By volume the 1998 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.
1.strong smell of gas when stopped at a red light or stop sign 2. Found to be a fuel rail leak between the no.3 and no.5 injector. Raw fuel leaking up under the hood could be ignited if there is an ignition source. (such as a back fire, leaking spark plug wire) 3. Replace fuel rail.*ak
The ABS traction control was not working and the dealer was unable to resolve the problem. The vehicle has been in and out of this dealer repair shop for this problem since aug. 2002 and the intermittent problem with brake failures and extended braking distance keep recurring. *jb anntena stuck up. Power antenna assembly replaced. Oil level low and oil light is on. There was no reading on the dipstick. Had to add two quarts of oil after driving 1500 miles. Oil life indicator was reset. Piston, rod and oil rings replaced. Drivers side headlight cover fell off with bulb burnt out. Headlamp housing assembly replaced. Consumer went to start vehicle and it wouldn't start. Battery replaced. Catalytic converter rattling. Drivers side heated seat/switch inoperative. While giving gas hesitates; struggles up a hill. Spark plug wire replaced. Notification by postcard. Ordered parts. Drivers side window won't go up. Replaced left door window switch. Ses light on. Exhaust recirculation valve (EGR) replaced. Transmission makes a grinding noise on fast acceleration. Dealer found the exhaust pipe at the rear of the converter shifting a cross…
The ABS traction control was not working and the dealer was unable to resolve the problem. The vehicle has been in and out of this dealer repair shop for this problem since aug. 2002 and the intermittent problem with brake failures and extended braking distance keep recurring. *jb anntena stuck up. Power antenna assembly replaced. Oil level low and oil light is on. There was no reading on the dipstick. Had to add two quarts of oil after driving 1500 miles. Oil life indicator was reset. Piston, rod and oil rings replaced. Drivers side headlight cover fell off with bulb burnt out. Headlamp housing assembly replaced. Consumer went to start vehicle and it wouldn't start. Battery replaced. Catalytic converter rattling. Drivers side heated seat/switch inoperative. While giving gas hesitates; struggles up a hill. Spark plug wire replaced. Notification by postcard. Ordered parts. Drivers side window won't go up. Replaced left door window switch. Ses light on. Exhaust recirculation valve (EGR) replaced. Transmission makes a grinding noise on fast acceleration. Dealer found the exhaust pipe at the rear of the converter shifting a cross…
Also reported on the 1998 Cadillac Deville
Headlight failure or clouding
Other electrical problem
Other engine problem
Other steering problem
ABS module or sensor failure
Premature brake pad or rotor wear
How far this goes
Complaints are voluntary, so 13 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 1998 Cadillac Deville?
Across 8 owner reports that included an odometer reading, half were filed by 10,000 miles. A quarter were filed before 10,000 miles and a quarter after 10,000 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 1998 Cadillac Deville?
13 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