Improperly Adjusted Valves May Cause Emissions Failure/Rough Idle on Toyota 4Runner

Problem Description and Possible Solution

A rough idle and even an emissions inspection failure for high HC and CO can be caused by improperly adjusted valves. Also, exhaust valves may become to tight which can lead to valve failures. Our technicians tell us that regular valve adjustment inspections are a must.

Problem Data
RepairPal Verified
Average mileage: 221,617 (180,000–289,000)
7 model years affected: 1992, 1993, 1994, 1995, more1996, 1997, 1999
9 people reported this problem
Viewing 1 - 3 of 3 comments
rattle on acceleration maybe valves
Idles poorly but runs well at higher RPM's. Won't pass smog due to high hydrocarbon reading.
Rough idle when I'm at a stop... no CEL, though...