QuestionQUESTION: I have a 2000 Ford Ranger 4.0L. For the last 2 months or so when I start the truck the idle immediately falls very low (400-600 rpm), and has become very rough and stalled twice, but usually jumps up after 10-30 seconds. Recently the check engine light came on, so I took it in, code read misfire in cylinder #6. A junked up spark plug seemed to be the culprit, so replaced all spark plugs (Motorcraft platinums) and cleaned fuel injectors (possible carbon buildup--engine has about 160K miles on it).
Now the check engine light is off, but the truck is still idling low at start, and the fuel economy seems to have tanked on the last fill-up, though all driving since then was highway. The truck usually pulls 18-22 on the highway, was down to 13. Once warmed up it seems to run fine, but occasionally idles rough at a stop. On rare occasion when pulling to a stop the brakes feel spongy-almost as if the anti-lock were on, though traction and road surface were perfectly fine.
In February I had to replace the intake manifold gasket, but otherwise just regular maintenance in recent months. I use Mobile full synthetic 5w-30, Motorcraft oil filters, K&N air filter, and prior to the spark plugs & FI cleaning I ran a bottle of Lucas fuel system cleaner through the tank. Fuel filter was changed about 40K miles ago.
I had some vehicle vandalism (slashed tire, bad apartment building) back in April, so I bought a locking gas cap and it has been on since.
If you can offer any help on this I would be incredibly grateful. I'm not particularly repair savvy, and have only done the most basic items, like oil changes, myself. The intake gasket replacement was done at a Ford dealership and recent spark plug/carbon cleaner were done at a local shop, which backed a tow truck into the driver's door of my truck, so they've had to do body work on it. I live in a tiny town with few repair options and anything is better than walking into a shop and letting them guess at what the problem might be at the expense of my wallet.
Thank you very much for your time, and have a great weekend.
ANSWER: Check you're throttle body yourself. Carbon collects in between the idle air control valve and the butterfly valve. I use a cotton towel, occasionally a toothbrush, and air intake and throttle body cleaner.
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QUESTION: Hi James,
Thank you very much for the quick answer. I bought some intake/throttle body cleaner and did a little brushing around and behind the butterfly valve in the throttle body. I used a toothbrush, which did come back black on the tips, but I didn't get to spend much time on it. I did seem to notice an improvement in the startup of the truck, but I had been driving it a lot during the day, so it was pretty warmed up already. I will start it in the morning after it has sat cold for over 12 hours and see if the start up is still good. If not, would you recommend continuing to clean the throttle body, or try something else? I didn't use much of the throttle body cleaner (looked behind the butterfly with a flashlight and there weren't huge deposits of carbon so I didn't feel like I needed to use the whole spray can as the can directions state...).
Also, please disregard the mileage issue. I've done some highway driving over the last 2 nights and filled after hitting 3/4 of a tank each time: first fill the truck averaged 21.3 mpg, 2nd time got 23.9, so improvement in the economy.
Thanks again for the advice, your expertise and time are very much appreciated. Also, do you know if 2000 Rangers have maintenance free chassis? I was under the truck looking to lube the balljoints but couldn't seem to find any place to attach a grease gun...
Again, thank you, thank you, thank you...
ANSWER: You ar every much welcome. As far as I know they are maint. free.
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QUESTION: Hi James,
Sorry to ask you for more advice, but I'm still having problems with the idle on the truck. The rough idle and near stalling seems to happen after very short drives.
I drove the truck a short distance in town, ran a quick errand, and then started the truck up again. It idled extremely low, the engine shook and jerked, nearly stalled, then fired right up as it normally would.
If you can offer any other advice on what the problem could be, or potential solutions, I would be grateful. This is driving me nuts.
Have a good one.
AnswerChange the plugs and wires. The wires may have a wear spot that becomes problematic when the truck heats up. Be sure and get the gap correct. Never assume that the gap is preset. Also, only use either motorcraft of autolite spark plugs. Has the check engine light come bask on? I believe that the #6 spark plug wire is you're culprit. It does get really close and touches the intake in a few spots. You're spark plug gap is .054.
