1987 Jeep Comanche Hesitation at 2000 rpm

1987 JEEP COMANCHE
130,000 MILES • 6 CYL • 2WD • MANUAL
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NVSMITH
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-This is similar to another question about Comanches.
-I have a bad spot at 2000 rpm. The engine falters & if I maintain that rpm will start backfiring. The engine has OBD1 & doesn't show any problems.
-I'd say it was a timing issue but don't know how to adjust the timing.
-I've replaced the plugs, the plug wires, the O2 sensors & now wonder if the problem is with the ECU.
-Oh, the crank and throttle position sensors test okay.
Mar 27, 2009 at 5:08 PM
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RASMATAZ
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Engine Hesitating or Stumbling could be caused by the following:

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
Mar 27, 2009 at 5:25 PM