98 yota 2.4l 190k mi. 5 spd. Truck started misfiring real bad every time I hit the gas. Autozone diag says it's a misfire on cyl 4. changed all plugs, checked all wires by swapping and trying to get the misfire to follow a certain wire, checked compression and it was fine, (even a little high). Plugs and exhaust smelled like gas. Could it be valves? Fuel injector?
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1998 Toyota Tacoma
Question: Why is my truck misfiring so bad without plug, wire, or compression problems?
Answer #1MATCO57 January 06, 2012, 14:10Enthusiast
You need to do a compression test on engine. No more than 20% difference.
What does the vacumm gage do when running?
Answer #2Fritzy 1 January 06, 2012, 17:37Rookie
check air sensors. fuel mix problem
Answer #3patrick mannion from Greg Solow's Engine Room, January 06, 2012, 20:47Master
Check valve clearance if over 120k its a possibility (shim adjusted). Check compression is even in all cylinders.