Bad Idle, Maybe alternator?

[Boodrodon Dykes]

It just started yesterday. When in drive and I am at a light or stopped, the ST seems to want to stall. It idles at 500 but dips to 50-100. I also hear a clicking noise, and seem like it is the belts stopping and then going again. The battery guage on the instrument panel is a little below the half way mark. Could it be the Alternator? I checked the belts and they seem to have enough tread. If it helps, I have the Xcal2 87 octane Perf. tune. Also I have a 10" sub, 800 watt amp, and a flip down screen. (maybe too much to handle?) Thanks in advanced.





Boodro

 

[Todd Z]

Could be the AC system is low on freon and the compressor is clicking on and off is loading the engine and the computer does not know it.....Also you can raise your idel with the xcal 100 rpm or so...



Todd Z

 

[Jeff C]

Get your battery and alternator tested for free at Advance Auto Parts or Autozone.



Sounds like: Cracked elbow or clogged PCV. I replaced my PCV yesterday and it idles soooooo much smoother, and the old one only had 30k on it.

 

[Boodrodon Dykes]

Todd- I had my freon reloaded last summer, and I hardly use my air conditioner , I usually have my windows down.



Jeff- I already replaced the usual cracked elbow. As far as the PCV I havent done that yet, Ill check into that.



Any other suggestions?

Thanks





Boodro

 

[Todd Z]

Check to see if the clicking is the AC compressor going on and off.....



IT is not uncommon for the ac system to have a leak even after you just had it filled...





Clean the Iac ?? Adjust the tbody a little ??



Todd Z

 

[Bill Ellis]

If you had to add refrigerent, then it has a leak. A/C doesn't have to run for refrigerent to leak; it's always under pressure.

 

[Richard L]

I agree with both replies above.



90%+ of the bad idle problems are caused by a dirty IAC valve. (Idle Air Control valve), so that should be the first thing to check.



If the engine does not idle fast enough, your alternator may not charge the battery enough and the AC kicking on can cause it to stall. Get your Idle speed corrected and then see if the alternator/battery don't come back to normal. Also, when your AC kicks on, the ECU should automatically adjust the engine idle speed to compensate for the AC compressor load. If the AC is dragging the idle down enough to stall the engine, your IAC is probably dirty and cannot properly adjust the idle.



...Rich

 

[Boodrodon Dykes]

I Just took it out for a 5 minute test drive, and it was fine. Didnt do anything at all. I cleaned the IAC last summer, how often would you say to clean it? I hope it will go away, but I doubt something like that just dissapears. Thanks again,





boodro

 

[Yardsale]

Boodro, you noted that you don't often use the A/C, but not whether you experience this problem with it on or off. Does it do this with the A/C off? If so, it's not the A/C.



I'm thinkin' IAC too.

 

[Chris Kulbaba]

Wow after all I went thru on this everyone didnt even suggest what fixed my problem.



Buy some TB/Intake Cleaner, and use it.



Problem solved.

 

[Richard L]

XST,

Nobody guessed your problem because you said you cleaned your throttlebody and intake with the seafoam treatment. Had that been done right the first time, you would have solved your problem. That's one of the big problems with diagnosing problems across the Internet, you don't know the quality of the work/diagnostics being done on the other end.



Cleaning the IAC is the first thing and probably the easiest and cheapest thing to do. It probably solves 90% of the bad idle problems in the Sport Trac. Next would be looking for a vacuum leak (the notorious split elbow), and then cleaning the throttlebody and intake.



...Rich

 

[Jeff Harwanko]

Ran into this same problem last winter. I cleaned the IAC etc. The culprit ended up being a low engine idle speed. When you run your heat in any setting except for "floor only" the A/C compressor cycles on to remove humidity from the incoming air. When the compressors cycles on this is an additional draw on the engine, and therefore the idle speed dips. If your engine idle speed is set to low, the A/C compressers senses that there is not enough speed (or energy) to run the compressor, and the compressor cycles on and off (hence the clicking noise that you noticed). Check the "projects" section. I believe that there is a write up on how to adjust your engine idle speed. Once I adjusted my engine idle speed back into spec., the problem went away. Hope this helps!

 

[Richard L]

DE-Trac,

I disagree with just adjusting the idle speed for the following reasons.



If the engine has been running fine for some time and suddenly developes a rough or slow idle, it indicates that there is a problem usually related to a dirty IAC, dirty intake, or accumilation of carbon (dirt) just behind the throttle plates in the throttlebody or intake. It can also be caused by some exhaust gas getting past the EGR valve and intering the intake airstream during idle. It can even be caused by a cracked or leaking vacuum hose.



The problem needs to be diagnosed and the offended problem corrected. The idle adjuster screw is designed for fine tuning the idle speed after the throttlebody had been removed or linkage dettached. Simply cleaning the IAC, intake and/or throttlebody will insure there are not causing a problem.



If you do not diagnose and correct the problem before you start changing the idle adjuster screw, you are only covering up the real problem and later, it will come back to bite you.



If you have a brand new Sport Trac that idles rough, you should take it back to the dealer to fix. If it's not a bad IAC they will probably just adjust the idle adjuster screw, which is the appropriate action if all the other components are working correctly.



...Rich

 

[Chris Kulbaba]

RichardL, I dont know how anyone could screw up the seafoam... its quite straight forward. I ran the truck, sucked up 1/2 the bottle of seafoam with the brakebooster hose, let it stall out and sit for 15 mins, start it up and let it run for another 30 mins, and drove around for a good hour or so.



I dont see much room for error at all. I did it properly, and this didn't solve my issue, so I would say the seafoam doesnt work as well as the TB/Intake cleaner.