engine surge at light throttle

[2011GT]

Ok. I have a few problems. When the engine is completely cold soaked when I go to start the engine makes a few loud chirping noises. This only last a few seconds. I put a new belt on to try and solve the problem but no luck.

Problem 2
when cold and being very light footed on the throttle the engine hesitates. When warmed up it still hesitates but not nearly as much. To try and fix this problem I cleaned the iac, mass airflow sensor, throttle body, egr valve. New plugs/wires, EGR pressure sensor.

 

[Big Jim M]

hmmmm

Ok. I have a few problems. When the engine is completely cold soaked when I go to start the engine makes a few loud chirping noises. This only last a few seconds. I put a new belt on to try and solve the problem but no luck.

Problem 2
when cold and being very light footed on the throttle the engine hesitates. When warmed up it still hesitates but not nearly as much. To try and fix this problem I cleaned the iac, mass airflow sensor, throttle body, egr valve. New plugs/wires, EGR pressure sensor.

Problem 1.. Sounds like the tensioner and idler bearings need to be replaced.

Problem 2.. Most likely a new IAC will fix this problem.

Big JIm

 

[TheUgster]

...I just did a full flush and refill a week or so ago, and it's already turning brown again. Check under your harmonic balancer for leaks, my water pump is shot and leaking every once in a while, I doubt that's causing the rough idle, but I'm inclined to believe that's causing the rusty coolant, at least in part. I really wish I could figure out why it idles rough on first startup, nearly stalling itself out, sounds like we're in the same boat here. I'm gonna check the TPS and MAF this week, but I think you've already exhausted (pun) those troubleshooting steps.

 

[2011GT]

Ill try a new iac. Makes sense considering it idles at 1400rpm most of the time. Occasionally it will come down to 900 rpm.

 

[2011GT]

Ok I put on a new iac. Now when slowing down to a stop the engine will stay reved to 2500rpm until I come to a complete stop. Once at a complete stop the engine idles down to 900.

 

[Froggmann]

Check the DPFE, or unplug it and drive it around see if the surging goes away.

 

[TOPGLOCK]

Disconnect the battery for 20-30 min. Every time I
Have replaced any sensor I always removed the negative
Battery cable. Never had any trouble. Try it and let us know.

 

[2011GT]

Disconnect the battery for 20-30 min. Every time I
Have replaced any sensor I always removed the negative
Battery cable. Never had any trouble. Try it and let us know.

didn't do anything. I searched for this problem I'm having and it's fairly popular. Except nobody has a fix...

 

[Froggmann]

Unplug the DPFE.

 

[fairman86]

im having the same issue with my 2.5l cold it idles a lil rough, and hesitates on the first 1/8 throttle, from idle a quick slap of the pedal and the engine will buck. also doesnt drop rpm''s fast while shifting. ran a very pricy scan tool (updated yearly), and it said that my short term fuel was at 33, so idle short term its trying to dump wayyy too much fuel into the system, long term was 3 tho, so ive redone a few wires, and it ses to get better when i disconnect the vacuum line off the egr valve.. still havnt figured out the main cause.

 

[Earl43P]

http://www.therangerstation.com/Magazine/Summer2009/idler-tensioner-pulley.htm

I suggest you start the (cold) engine (for a short time) with the serpentine belt completely removed.

If you still get the chirp, replace the Cam Synchro (before it fails and causes a complete loss of oil pressure and your engine seizes).

As far as the surging, I have experience with the DPFE causing that, but yours was replaced. Unlike the other advice given, I suggest you disconnect the vacuum line from the egr valve itself and drive it around for a day or so (plug the open vacuum line).

You should get an EGR code. If that cures the surging, you can be sure that EGR is indeed the cause (very common on Fords by the way). You could have bad silicon tubes from the exhaust to the DPFE and you could have carbon blocking the egr passages. Very rarely does the egr valve itself fail.

http://www.tomco-inc.com/Tech_Tips/ttt33.pdf

You could also have a bad DPFE (again) if this vehicle is used extensively on short trips. My 4 mile commute was hard on DPFE's because the moisture never got burnt out of the silicone tubes. Disassembly of the DPFE showed corrosion deposits covering the diaphragm. Most carry a one-year warranty.



Welcome to The Ranger Station!

 

[TOPGLOCK]

My 98 ranger did the same exact thing your talking about. I replaced the IAC and now
It idles perfect. It's hard to believe its not on yours. Same symptoms....weird......

 

[2011GT]

Unplug the DPFE.

Ok. I'll try this tomorrow. I just replaced it about 2 weeks ago though...

 

[Viper Command]

With my 3.0 I had the same problem ( high idle, lumppy under light throttle)

I had a vac. leak at the manafold causing the high idle, I replaced my O2 sensors and now it accelerates smoothly.