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hoerth 07-26-2011 11:08 PM

another rough idling scenario -- '99 3.0L
Truck started rough idling last week and I've reviewed lots of forum threads for solutions. But still is rough and really gets bad at 40 mph and 1500 RPMs. Lousy power going uphill, I started by adding fuel stabilizer and Lucas injector cleaner to the fuel tank. Depleted the gas and added more injector cleaner with next fill up. Changed plugs and wires. Put in platinum Autolite plugs. Cleaned MAF sensor. Replaced the $50 DPFE sensor (Delta Pressure Feedback Valve). No visible loose or worn hoses. So what do I try next? Clean Idle Air Controller (IAC)? Can I use the MAF Sensor cleaner on that since I bought a whole can but only needed to use a little? Or carb cleaner? Does changing fuel filter make a difference? Throttle body cleaning may help from what I see in other posts. What about EGR valve. Clean or replace? Seafoam a last resort?

Additional notes some of which may be related: I ran the gas tank down real low just prior to this happening. Using O'Reilly's scanner CAN )BD2, I get codes PO305 (cylinder 5 misfire) and PO174 (system too lean bank 2). 160,000 miles on the truck. Serpentine belt's been squeaking but I remedied that by cleaning grit off the center pulley using sandpaper. Front passenger side floor's been getting wet which sounds like a heater core issue.

hoerth 07-27-2011 10:36 PM

Re: another rough idling scenario -- '99 3.0L
For anyone viewing this, just want to alert you that the problem appears to be solved with the cleaning of the Idle Air Controller. And it was one of the simplest things. Remove two screws, spray carb cleaner into it to clean out the carbon buildup. The buildup was interfering with a small metal pin moving in and out. Cost over $100 for the other things and several hours but probably worth having done them. Ultimate solution though cost pennies and 10 minutes.

hoerth 07-30-2011 11:03 AM

Re: another rough idling scenario -- '99 3.0L
Spoke too soon. Problem returned the next day. On to the next things on the list. EGR valve clean and throttle cable clean. Might Seafoam.

dyna mite 07-30-2011 12:01 PM

Re: another rough idling scenario -- '99 3.0L
i had rough idling and lack of power on my '98 4 cyl ranger w/188,000 mi on it. replaced egr valve and it fixed it. i had no check engine light or trouble codes tho. also had noticeable jerking going uphill previously that got progressively worse- that was fuel filter which i replaced at 175,000 mi.

Dcrymes99ranger 07-30-2011 12:04 PM

Re: another rough idling scenario -- '99 3.0L
Idle air control valve. Change it.

hoerth 07-30-2011 04:34 PM

Re: another rough idling scenario -- '99 3.0L

Originally Posted by Dcrymes99ranger (Post 502541)
Idle air control valve. Change it.

I cleaned it with carb cleaner and thought that dealt with at least that possibility. Some carbon was on the pin. But you still think replacing it is necessary?

Fordzilla80 07-30-2011 06:14 PM

Re: another rough idling scenario -- '99 3.0L
Cleaning the IAC only works as a preventative measures. If your idle is severely affected, then it's a good possibility the damage to the IAC has already been done.

I would check your EGR as was mentioned before.

dyna mite 07-31-2011 12:08 AM

Re: another rough idling scenario -- '99 3.0L
there are ways to test your egr i looked up somewhere on line but the easy method is to drive down the freeway at a pretty good speed(i went 75-80mph) for a few miles(i went 10) then get off and come to a stop. truck should run ok at steady high speeds but will idle rough at stop. mine would also occasionally backfire slightly when pulling out from stop. exhaust pipe was also blackened with soot.

mt1986 08-01-2011 02:15 PM

Re: another rough idling scenario -- '99 3.0L
check the electrical connections at the fuel injectors if there is corrosion in there it will cause all sorts of weird problems i used PB blaster and an old toothbrush to clean mine just be sure and use dielectric grease when you go back together to insulate the connection, good luck

SteveKing84 08-01-2011 02:45 PM

Re: another rough idling scenario -- '99 3.0L
I've yet to clean this because I haven't had the need, but I'd be hesitant to use anything but electrical cleaning spray...can't think of the brand I have now though.

Petesis 08-01-2011 04:11 PM

Re: another rough idling scenario -- '99 3.0L
Thank you but I don't have anything to say. I am looking for info. My ranger was idling rough and now I am getting a check engine light. water temp is good. volts good, oil pressure is good.

hoerth 08-01-2011 10:41 PM

Re: another rough idling scenario -- '99 3.0L
Thanks for all the advice so far. Will have to wait until the weekend to get back at it. I will report on any successful strategies if I'm lucky enough to find a solution.

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