OK, here's the deal. I am taking my '03 Sport Trac 4x4 to the garage tomorrow morning (not a Ford dealership) for a fuel filter replacement. This is where I am going to start for resolving my slight idle fluctuations when sitting still. I belive the present fuel filter is the original and there's 45K on the truck, so I'm hoping that the new filter and some fuel injector cleaner will resolve the idle issue.

There are some other issues I'm going to have checked out while I'm there, and I would like to have everyone's advice as to what I should ask the mechanic, since I know very little about auto repair.

First: I have a power steering fluid leak from the passenger side rack boot, for which I have already received a replacement quote from the Ford dealer, and should be getting exchanged in the near future. But while I was looking under the truck last night, I noticed that the axle and shock behind the boot had sludge on them. So my questions are, could the sludge on the axle and shock be from power steering fluid that has leaked from the rack boot, or is a sign of axle and shock failure? How can I tell what the problem is?

Second: Over the last two weeks, I have noticed that I am feeling every little imperfection in the road. I feel the vibrations more prominently in the seat as opposed to the floorboard or steering wheel. What are possible causes for the vibrations? Also, while inspecting the rear end last night, I didn't see any problems with the rear shocks, but noticed the presence of fluid on the driver's side of the rear differential case and the same type of fluid on the driver's side rear axle, where it enters the rear differential case. No puddles in the garage, which leads me to believe that it's not dripping.

Looking forward to your input, thanks!

 

Also, I should've added that the vibrations I'm feeling in the seat are constant, meaning that there's really know difference if I'm traveling 25 mph or 65 mph.

 

First, a fuel filter probably won't fix the idle fluctuation, unless your having a problem when under heavy load ( like hard full throttle ). As for the sludge, it may well be from the p.s. leak from the boot, if they get enough in them it pushes out and makes a good mess. The rear axle seal is probably leaking not that big a problem to fix however just be careful reinstalling the axle.

 

Ranger88a,

Thanks for the advice. Could you let me know why you don't think the fuel filter will take care of the fluctuation. Sometimes, it feels like the truck is going to stall at stop lights in the morning on my way to work...almost like it is not getting enough gas. That's why I thought it may be the fuel filter. Any other causes you can think of? I know that I have read several posts on the board about IAC and PCV, but those problems sound a lot more severe than what I am experiencing. Thanks for the help.

 

Your problem could very well be the IAC. Try cleaning it and see if that makes a difference. Also, have you had the computer codes pulled, and if so, what did they reveal?

 

It's probably time to change the fuel filter but I doubt that is the source of your idle fluctuations. My first thoughts would also be the IAC valve.

Of course I had a similiar problem with my '03 starting at 29K miles and the problem turned out to be the PCM.

 

If a fuel filter was so plugged that it would effect the idle (very little fuel burned) there is no way that vehicle would drive 55. IAC sounds like a better bet as would MAF but before you spend a penny, check your codes.

 

Thanks for all the advice guys, I appreciate it. I had the truck checked out on Saturday, and everything appeared to be in good working order. Three of the four tires were out of balance, so I had them corrected and rotated, which seemed to take some of the bumpiness out of the ride. Also, I had all four tires inflated to 35 psi (cold fill) during my last oil change. I finally read the Ford specs on the door and discovered that the proper fill was 35 psi front, 30 psi rear, so I fixed that as well. I am going to assume that the slight vibrations I can feel when traveling over road seams are directly related to the fact that it's a truck. Front axle and shock looked good as well, the sludge that was present was from the power steering fluid that was leaking out of the rack and pinion dust boot.

Also, fuel filter was changed...and you all were right, the idle fluctuation is still there. I will keep the suggestions about the IAC, MAF and PCM in mind, when I try to correct the issue in the near future. As for pulling the codes...will a code reader reveal error codes when the check engine light is not on? I ask because my check engine light is not on, and I thought that if I had a problem with either the IAC, MAF or PCM that the light would illuminate. Thanks again for the advice.

 

Yes, there can be codes stored even if the CEL is off.