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Idles rough

Tiny
MULO
  • MEMBER
  • 2002 FORD RANGER
Idles rough at a stop light, need to put it into neutral, gently press the accelerator to bring RPM's back up. Sometimes it dies off. Once I put it into drive it runs great.I have already changed the fuel filter. Could it be a faulty vacuum line and if so how do I check it and/or repair it
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Sunday, September 20th, 2009 AT 2:31 PM

46 Replies

Tiny
RANGERDANGER17
  • MEMBER
  • 224 POSTS
Well it sounds more like sensor problem but both a sensor problem and a vacuum hose leak would cause the check engine light to come on if thats on advance auto can test it and tell you whats wrong

this guide can help us

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

your electronic idle control switch might be bad that tells your engine how much gas to give while in park or neutral

but have advance test the check engine light first cause it could be several different things
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Sunday, September 20th, 2009 AT 7:48 PM
Tiny
JOHN KAHLE
  • MEMBER
  • 7 POSTS
  • 2002 FORD RANGER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 90,000 MILES
We have 4 codes, PO171-system too lean bank 1, PO174- too lean bank 2, PO 301, cyl 1 misfire, andPO 305, cyl 5 misfire
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
Ok so lets me get some info first. What have you done at this point. Plugs, wires etc. Get back to me with that and we will go from there. Thanks.
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
JOHN KAHLE
  • MEMBER
  • 7 POSTS
The only change so far has been new spark plugs
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
JOHN KAHLE
  • MEMBER
  • 7 POSTS
Just changed the wires and it runs somewhat better but it doesn't have much power. Once it gets above 3000 rpms the motor shakes the truck and goin up hills 45 mph is about max speed
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
INNERCLAW
  • MEMBER
  • 2 POSTS
  • 2002 FORD RANGER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 72,000 MILES
I currently went to autozone for a check engine light. They pulled the code which read- "Air/Gas mixture to lean". They said to replace the Mass Air Flow sensor. Which I Did. I pulled the Cables from the battery to reset the ecm but The check engine light would come back on after 30 mins of driving. Also the truck runs good when driving only bad idels at a stop or in park havent tried the neutral yet. Goin to change spark plugs now to see how that goes.
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check the idle air control valve, EGR and PCV valve

A lean fuel condition can be caused by:

* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (Use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (Try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
ROBERT WHATLEY
  • MEMBER
  • 5 POSTS
Sounds like the ignition coil is going bad. Had to replace the one in my wifes car that was throwing the same codes
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
INNERCLAW
  • MEMBER
  • 2 POSTS
Found the problem pcv elbow hose had a hole. Now fun task of finding one thanks for your help
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
SUPERSLADE2008
  • MEMBER
  • 1 POST
  • 2002 FORD RANGER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 950,000 MILES
My ford ranger has started ideling rough when I start it in the morning to warm up it dies. And when im setting with it in gear at a stop light it will idel rough then die.
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
BLACKOP555
  • MECHANIC
  • 10,371 POSTS
Sounds like its time for a throttle body cleaning service to be performed on your vehicle.

Check to make sure the IAC modules pintle moves freely without any binding also.
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
JASON COOK
  • MEMBER
  • 6 POSTS
Try the idle control valve
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
DEREK97116
  • MEMBER
  • 41 POSTS
  • 2001 FORD RANGER
  • 74,000 MILES
I have a 2001 ranger and I have a rough idle I replaced the iac maf sensor pcv valve and cleaned the throttle body but still no change It runs good while driving just at idle it stumbles not to the point where it stalls just poor idle any advice would really help thanks
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
DRCRANKNWRENCH
  • MECHANIC
  • 3,380 POSTS
You could have a vacuum leak. Sometimes a bad O2 sensor will cause a rough idle as it gives the incrrect air/fuel value to the computer causing a rough idle.
Also, the throttle position sensor could play some part, but not as likely.
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Vacuum leaks, compression test, check plugs and ignition system, scan for any unresolved faults, not all faults will set a light, check EGR operation, start here.
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
DEREK97116
  • MEMBER
  • 41 POSTS
I did hook it up to a scan tool there Is no miss fires and no codes poped up and I did change the throttle position sensor as well I think its a vacum leak but wouldent that show up on the scan tool and do you think plugs and wires would solve the issue even when its not miss fireing and the o2 sensor where is that located and what does that do to make it not idle right
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
DRCRANKNWRENCH
  • MECHANIC
  • 3,380 POSTS
You can test the plug wires for resistance by the foot. I do not have specifications for that though. I will try to find them becasue that is possible.

The O2 sensor will be in the exhaust path before the catalytic converter. If it thinks the engine is running lean it will put too much gas in the mixture and it will run rough. Same goes for it thinking it is rich, but this is harder to detect and will possibly damage top end parts.
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
DEREK97116
  • MEMBER
  • 41 POSTS
With the o2 sensor wouldent it spit a code if that was bad and the only time the check engine light has come on was for the egr valve and I took it to a mechanic and he said the egr was fine but he changed the maf sensor since that I haven't had the light come back on and I have a buddy with the scan tool and no codes at all show up so idk
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
DHSANDY
  • MEMBER
  • 1 POST
  • 2001 FORD RANGER
Engine Mechanical problem
2001 Ford Ranger Four Wheel Drive Automatic 88200 miles

When reading the Diagnostic Codes I come up with
P1401
P1401 Heated Catalyst Current too High During Heating (Bank 1)

P0171
P0171 System too Lean (Bank 1)

P174
P0171 System too Lean (Bank 1)

P0300
P0300 Random/Multiple Cylinder Misfire Detected

Can you give me some idea of just what these codes mean.
If it is something simple I would like to fix it myself.
Also, I just installed a new EGR after reading a question in your website from someone that was having a problem identical to mine. The new EGR valve did not seem to have any effect.
Thanks for any help
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Monday, January 6th, 2020 AT 10:13 AM (Merged)
Tiny
RENAUDTN
  • MECHANIC
  • 636 POSTS
Hi there,

P0171/174 mean your ratio air/fuel is messed up. You have too much unmetered air reaching your engine.
P0300 is a random misfire codes. Several of your cylinders are misfiring. It's probably the result of the extra air. If you fix the P0171/174 codes I'm confident it'll fix P0300 at the same time.

Okay, I can't guarantee it for sure, but a lot of time with Ford cars, when you have these codes, the culprit turns out to be the DPFE sensor. This sensor is part of your EGR system. I'm not sure where it is located on a 2001 Ranger, but I'm thinking if you look at your egr tube (the pipe that connects the exhaust manifold and the egr valve), the sensor is probably connected to it by two small hoses. By the way, that's what the P1041 code means: something is wrong with your DPFE sensor.

Take a look at it and make sure the vacuum lines are connected; but it's very possible you'll have to replace the sensor (around 50-60 buck for an aftermarket one I think).

Hope this helps.
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Monday, January 6th, 2020 AT 10:13 AM (Merged)

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