1998 Toyota Tacoma Rough Idle

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BLUEJEAN
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I have a 1998 toyota tacoma 2wd pu with a 2.4 eng. The truck has 90,000mi. on it. I gave it a full tune up, including the wires. I replaced both o2 sensors , egr valve, and throtal positioning switch. I also replaced the seals around the injectors, cleaned the intake and throtal body. And it still idles rough. Mind you, the last person who own this truck never gave it a tune up, he just did oil changes every 3,000mi. What can it be?
Sep 4, 2006 at 4:24 AM
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GLENERIK
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Could you be more specific as to what you mean by rough idling? When does the idle seem "rough"?
Sep 6, 2006 at 1:29 PM
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RASMATAZ
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Did you adjust the initial voltage on the TPS
Sep 7, 2006 at 11:07 PM
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BLUEJEAN
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This might seem like a dumb question, but how do you adjust the initial voltage on the TPS?
Sep 11, 2006 at 12:31 AM
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RASMATAZ
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loosen the TPS and than backprobe it. if it checks out check the IACV

BTW any OBD2 codes?
Sep 11, 2006 at 1:54 AM
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Suggested Repair

Loosen the throttle position sensor and backprobe it to check and set the initial voltage. If the TPS checks out, inspect the idle air control valve and scan for OBD2 codes.

Conversation Summary

A 1998 Toyota Tacoma 2.4 with 90,000 miles still idles roughly after a full tune-up, new O2 sensors, EGR valve, throttle position switch, injector seals, and intake and throttle-body cleaning. An expert asked whether the TPS initial voltage was adjusted, then advised loosening and backprobing the TPS, checking the IAC valve if it tests good, and looking for OBD2 codes.

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