Odd idle issue.

[fourwheelford]

Ok this just started happening today, I drive the truck for awhile and stop somewhere for a while and then when I start it back up it starts just fine but then it bogs down to about half its idle(about 600) it usually idles at 1000 or 950 and kinda climbs up to right about 800 . It doesn't seem to hesitate on the take off and when I stop its fine again. I unplugged the IAC and the idle dropped a bit and seemed to be a bit smoother and didn't throw a code, plugged it back in and the idle went up and got a little more rough. My honda does this sometimes on hot starts almost in the same fashion, it has been hot these last couple of days also. New plugs, new wires, new syncro, new filter oil is full, coolant is full, no codes, and recently cleaned the MAF sensor. It fires right up but the idle bogs down. Anyone know what might cause this?

Oh I am also running a tank of e85 for the first time since I got the truck, does it tend to cause hot start problems?

 

[fourwheelford]

Nobody has ever had this happen?

 

[McCormack]

My Ranger had some rough running and idling problems, and even though it didn't throw a code it turned out to be a bad DPFE sensor.

Other suggestions: check for vacuum leaks; if so equipped check the EGR valve to make sure that it's working properly.

 

[fourwheelford]

Thanks for the response, I have read a lot about that DPFE sensor and my truck has
101,383 miles on it so that could be the case, where is that sensor? And it does have an egr valve I will test it.

 

[fourwheelford]

Never mind I think I found it, is it the little gray box that is bolted to the intake with two vac lines coming out that go into the egr line? At any rate I cleaned the TB the IAC and the MAF again, the IAC was nasty and now my idle is smoother so that needed to be done. I also drove it today and it didn't do it again, I think it was a combination of hot start, nasty damp heat, E85 and probably the IAC needing to be cleaned. I guess I will just keep an eye on it till it totally craps out or doesn't.