2.5l rough/no idle - Ranger-Forums - The Ultimate Ford Ranger Resource

SOHC - 2.3L & 2.5L Lima Engines Discussions and Topics specific to the Lima 4 cylinder engines

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Old 07-20-2015
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Join Date: Jul 2015
Location: Jacksonville,Fl
Posts: 1
2.5l rough/no idle

I have a 99 2.5l that will run but have to have foot on gas pedal to keep it running...I've recently replaced all injectors, wires, plugs and coils....new fuel pump and filter...mass airflow sensor a couple years old...replaced the IACV and the TPC with no results...any clue on what can be wrong??? Please help!!!
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Old 07-20-2015
Join Date: Mar 2014
Location: Tampa
Posts: 39
Intake manifold may need some cleaning. Also check for leaking vacuum lines.
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Old 07-20-2015
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First turn on the key and make sure CEL(check engine light) comes on and then goes out, this is the computer running a self test and passing if CEL goes out.

Unplug MAF sensor and start engine, with MAF unplugged computer will use factory pre-set air/fuel mix tables, based on RPM.
The CEL should come on after starting, this is checking if computer is working, and can ID a problem like unplugged MAF sensor.

Double check firing order on exhaust side coil first(it's the only one used for starting)
Then check intake side coil firing order(this one is only used after engine starts).

Pull off the Air tube on the intake and use your hand to cover intake to "choke" air coming in while someone cranks engine to start, tests if you have a major vacuum leak, which I assume you would hear, but..............

Are you blowing out any smoke from the exhaust, i.e. a rich mix

Last edited by RonD; 07-20-2015 at 08:04 PM.
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