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Need Info

bass4x4

NAXJA Forum User
Location
Indiana
I have a 91, 4.0L, it idles great but when you accelerate it misses really bad. Any ideas on what it might be?

Thanks
eric
 
Could be hundreds of things that cause that symptom. Start out with new plugs, wires, cap and rotor. Clean the throttle body. Check your CCV hoses for integrity and flow. Could be guel pump, fuel filter, air filter. Intake manifold bolts loose? You aren't gonna find a silver bullet cure. Shall I continue?
 
Test the Throttle Position Sensor.

You should have 5 volts going into the TPS. At idle, TPS output voltage must be greater than 200 millivolts. At wide open throttle (WOT), TPS output voltage must be less than 4.8 volts.. The best is to use an analog meter (not digital) to see if the transition from idle to WOT is smooth with no dead spots. With your meter set for volts, put the black probe on a good ground like your negative battery terminal. With the key on, engine not running, test with the red probe of your meter (install a paper clip into the back of the plug of the TPS) to see which wire has the 5 volts. One of the other wires should show .26V (or so). The other wire will be the ground and should show no voltage. Move the throttle and look for smooth meter response up to the 4.49 at WOT.

Perform the test procedure again and wiggle and/or tap on the TPS while you watch the meter. If you notice any flat spots or abrupt changes in the meter readings, replace the TPS.
 
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