Throttle does not close — the V6 icing recall

Mitsubishi ran a safety recall on the V6 first-generation Montero because the throttle valve could ice up and stick, leaving the engine unable to drop back to idle. The remedy was a heated adapter plate under the throttle body. Owner complaints filed with the same regulator over the following years describe the outcome the recall was meant to prevent — a throttle that stayed open, a truck that surged from a stop, and in one case a rollover. The campaign record is listed against the first V6 model year only, while the owner complaints cited here come from the two later ones, so treat the model-year boundary as the paperwork's, not the fault's. Because the recall is decades old and these trucks have changed hands many times, a truck in front of you today may never have had the remedy fitted, and nobody can tell by looking. Anything that keeps the throttle from closing on its own is a safety-critical fault: do not drive the truck until it is fixed, and have the work done by a qualified mechanic.

Gen 11989–1991USSafety-criticalCommunity consensus

Do not driveNo lo maneje

Safety notice — Fuel system.

This affects a safety-critical system. Reference material only: for safety-critical work, consult a qualified mechanic.

Esto afecta un sistema crítico para la seguridad. Material de referencia únicamente: en trabajos críticos para la seguridad, consulte a un mecánico calificado.

Community consensus. This entry is not backed by factory documentation — treat its values and steps as a starting point, not as if they came from the factory manual.

Consenso de la comunidad. Esta entrada no se apoya en documentación de fábrica — tome los valores y los pasos como punto de partida, no como si vinieran del manual de fábrica.

Symptoms

You lift off the accelerator and the engine keeps revving instead of dropping to idle
The accelerator pedal feels held down or gritty, and does not spring back cleanly
The truck surges or creeps hard forward when you come to a stop
It happens on cold, damp mornings and not on warm dry days

Likely causes

Ice forming on the throttle plate holds it open once the engine has drawn moist cold air
The recalled heated adapter plate was never fitted to this particular truck
The throttle linkage or cable is binding mechanically, independent of the weather
The throttle return spring is weak or has been stretched and no longer snaps the plate shut

Diagnostic steps

Write down the weather each time it happens: cold and damp only, or any conditions?Points toIce forming on the throttle plate holds it open once the engine has drawn moist cold airRules outThe throttle linkage or cable is binding mechanically, independent of the weather
Look under the throttle body for the heated adapter plate and its coolant hoses, and ask a dealer whether the campaign was completed against this vehicle identification numberPoints toThe recalled heated adapter plate was never fitted to this particular truck
With the engine off, open and close the throttle by hand at the throttle body and feel for tight or gritty spots through the whole travelPoints toThe throttle linkage or cable is binding mechanically, independent of the weather · The throttle return spring is weak or has been stretched and no longer snaps the plate shut
Open the throttle by hand and release it: does it slam shut on its own, or drift back slowly?Points toThe throttle return spring is weak or has been stretched and no longer snaps the plate shut

Fix paths

Fit the recalled heated adapter plate

$–$$Difficulty 3/5

The remedy the manufacturer published is a heated adapter plate under the throttle body. A campaign this old is normally long past the point where a dealer will supply the part free, so treat this as a repair to pay for and source, not as a warranty claim.

Clean, free and re-spring the throttle linkage

$Difficulty 2/5

Clean the throttle bore and shaft, free the cable and linkage, and renew a return spring that no longer snaps the plate shut. This is the half of the problem that has nothing to do with the recall and everything to do with age.