1998 Ford Taurus Idle Problem

KRAUSY8515

MEMBER
1998 FORD TAURUS

Hi, I have a 1998 Ford Taurus SE with 116000 miles. It is an automatic with a 3.0L DOHC Duratec motor. I recently changed the plugs and wires, have switched to synthetic oil two oil changes ago, and within the last 16000 miles replaced the speed sensor on the transmission due to failure of the previous one. After driving in reasonably warm weather then letting it sit for 5 hours, I started it up but I got a drastic reduction in idle (usually around 800 RPM but it dropped to below about 400) and when starting from a stop I got a hesitation almost like the engine had no gas before it caught and returned to "normal." Driving at higher speeds the transmission shifted at odd times. Shifting into neutral at low speeds the engine would jump to around 3000 RPM but tapping the pedal would lower the RPM's to normal for that speed. The engine ran very rough when I stopped and nearly stalled when left to idle for 2-3 minutes only to run very rough at very low RPM's after that. Any help with what may be the problem would be greatly appreciated. Thanks

Saturday, June 2nd, 2007 AT 10:58 PM

1 Reply

RUDPRO

MECHANIC
224 POSTS

Is you service engine light on. If it is, go somewhere like an Autozone to get the trouble codes read. That will help a lot with diagnoses. I was first going to tell you to clean the throttle body. After checking, I found out your type of engine has a throttle body that should not be cleaned because of a protective coating on the throttle plate. I don't know any more about this, I'll look into it more or someone else reading your post might have more info. You can still check it by visually inspecting it and operating the throttle by hand, with the engine off, and seeing if it's sticking or not. This could also be your Idle Air Control Valve, your Throttle Position Sensor, or Mass Air Flow Sensor. You can check the IAC and TPS with a digital multimeter. Let me know if you want the procedure. The main thing is to get a scan if your Check Engine Light is on.

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Saturday, June 2nd, 2007 AT 11:24 PM