Mechanics

22RE STUMBLE/MISS

1985 Toyota 4Runner

Engine Performance problem
1985 Toyota 4Runner 4 cyl Four Wheel Drive Manual 202000 miles

Engine is a new long block with 16k - I have a stumble/miss or hesitation at cruising throttle position. Is somewhat noticeable during acceoeration but is much more prevalent when throttle is part-way. I have replaced & properly adjusted TPS sensor, had fuel injectors rebuilt with all new seals, fixed exhaust leaks and it runs much better but can't get rid of this stumble. Does not matter if engine is cold or up to temp.

Once throttle gets to a certian spot it starts to hesitate and gets worse as throttle is pressed a bit further, then will accelerate if continued to press throttle down - then as throttle is lifted there is a point where the condition stops and runs better. So if you press down the throttle around this point it actually hesitates more - let off and the acceleration increases. Any thoughts?
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Kenjans
April 14, 2008.



Check the Vane airflow sensor and fuel pressure

Vane airflow sensors as well as all the other types of airflow sensors can't tolerate air leaks. Air leaks downstream of the sensor can allow " unmetered" or " false" air to enter the engine. The extra air can lean out the fuel mixture causing a variety of driveability problems, including lean misfire, hesitation and stumbling when accelerating, and a rough idle.

Rasmataz
Apr 15, 2008.