QuestionQUESTION: Hello, I have a 98 Ford Ranger SuperCab, 4.0, 4x4, AT, 157,000 miles, and I've owned it since new. It's up to date on air and fuel filters and fluid changes. The past few weeks I've been experiencing a very rough idle on cold start-up after setting overnight. It idles rough for about 15-20 seconds and then smooths out and runs fine. I have no check engine light, no misfire or hesitation and I drive it on the Interstate to work 5-6 days, about 150 miles a week. No problems.
With Winter just round the corner, I'd like to get this fixed.
I'd appreciate any suggestions you might have.
Thanks, John
ANSWER: John,
Sounds like your cooling sensor is bad. Find where your sensor is and replace it. I bet that will take care of your problem.
Thanks for your question.
Jeff
---------- FOLLOW-UP ----------
QUESTION: Thanks Jeff, if the coolant sensor is bad, will the truck still reach normal operating temperature? The temperature gauge reads normal after warmup and doesn't go past the half-way point. Also, how many sensors does this truck have and location?
AnswerJohn,
Yes the sensor can be giving bad readings when the coolant is cold it is sending a wrong reading to the computer and the computer thinks your engine is already warm not causing the fast idle or cold idle to stay on, which in turn causes rough idle. As far as location of sensors, the best thing to do is Google location of sensors for your specific vehicle.
Thanks.
Jeff
