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  #1  
Old 04-08-2011, 03:44 PM
mentalmodel mentalmodel is offline
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Default Can't Figure it out

1998 Ranger, 3.0 5 speed

I am having idle and throttle issues.

Truck idles rough at about 700rpm, sometimes almost stalls out and then picks up to 1500 rpm. Other times it will stall out.

I have replaced 02 sensors, MAF sensor, Idle Air Control Valve, EGR and Spark Plug wires.

I have unplugged the IAC Valve and hardly notice a difference, but it's hard to start unplugged. Plug it back in, start the truck, idles rough, I give it gas and can smell the gas, I unplug the IAC and then it smoothes out eventually and will run. Also, checked voltage to IAC.

What's the deal?
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  #2  
Old 04-08-2011, 03:46 PM
DiabloBlanco DiabloBlanco is offline
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Default Re: Can't Figure it out

throwing any codes?
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  #3  
Old 04-08-2011, 03:50 PM
mentalmodel mentalmodel is offline
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Default Re: Can't Figure it out

Hopefully getting an OBD tomorrow.
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Old 04-08-2011, 03:52 PM
DiabloBlanco DiabloBlanco is offline
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Default Re: Can't Figure it out

Check your roller camshaft. Just a thought.
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  #5  
Old 04-08-2011, 03:53 PM
mentalmodel mentalmodel is offline
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Default Re: Can't Figure it out

Ok, thanks.
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Old 04-08-2011, 03:55 PM
DiabloBlanco DiabloBlanco is offline
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Default Re: Can't Figure it out

Does this idle problem only occour in cold weather? hot weather?
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  #7  
Old 04-08-2011, 04:04 PM
mentalmodel mentalmodel is offline
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Default Re: Can't Figure it out

I'm in the southwest, weather has been mild. This has just started within the last few weeks. The first noticeable thing was the jump in rpm's when I would push in the clutch to shift, and the rpm's would not drop at all with foot off the gas. When the rpm's eventually dropped, after about 5 seconds, it would idle at about 1500.
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Old 04-08-2011, 04:07 PM
djfllmn djfllmn is offline
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Default Re: Can't Figure it out

id check the TPS next/ check for a vacuum leak
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  #9  
Old 04-08-2011, 04:10 PM
mentalmodel mentalmodel is offline
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Default Re: Can't Figure it out

Can you tell me where the TPS is? Is it the sensor that attaches to the side of the throttle body?
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Old 04-08-2011, 04:11 PM
djfllmn djfllmn is offline
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Default Re: Can't Figure it out

that is correct
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  #11  
Old 04-08-2011, 04:30 PM
brinker88 brinker88 is offline
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Default Re: Can't Figure it out

Sounds like a vacuum leak to me
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  #12  
Old 04-08-2011, 05:12 PM
mentalmodel mentalmodel is offline
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Default Re: Can't Figure it out

Error codes are:

1504
1131
1151
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  #13  
Old 04-08-2011, 05:14 PM
DiabloBlanco DiabloBlanco is offline
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Default Re: Can't Figure it out

Yeah definitely a vaccum leak it sounds.
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  #14  
Old 04-08-2011, 05:18 PM
mentalmodel mentalmodel is offline
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Default Re: Can't Figure it out

Any suggestions of where to start looking? A usual suspect?
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  #15  
Old 04-08-2011, 05:24 PM
brinker88 brinker88 is offline
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Default Re: Can't Figure it out

P1504- Intake Air Control circuit malfunction

P1331- Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1

P1351- Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 2
CausesA code P1151 may mean that one or more of the following has happened:

Electrical:
Short to VPWR in the harness or HO2S
Water in the harness connector
Open/shorted HO2S circuit
Corrosion or poor mating terminals and wiring
Damaged HO2S
Damaged PCM

Fuel System:
Excessive fuel pressure
Leaking/contaminated fuel injectors
Leaking fuel pressure regulator
Low fuel pressure or running out of fuel
Vapor recovery system

Induction System:
Air leaks after the MAF
Vacuum Leaks

PCV system:
Improperly seated engine oil dipstick

EGR System:
Leaking gasket
Stuck EGR valve
Leaking diaphragm or EVR

Base Engine:
Oil overfill
Cam Timing
Cylinder compression
Exhaust leaks before or near the HO2S(s)
Possible SolutionsSee the above list of causes and go from there.

Sources: MotorCraftService.com


Hope this helps dude
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