1999 Ford ranger 3.0 V6 has a very Ruff Idle - Ranger-Forums - The Ultimate Ford Ranger Resource

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Old 12-07-2014
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Join Date: Dec 2014
Location: lawton,ok
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1999 Ford ranger 3.0 V6 has a very Ruff Idle

Hi, Clayton from Oklahoma here. Brand new to the Forum, Hope I can get Some Help. My 99 Ford Ranger Has a Very Ruff idle when I start it in the Morning. Some times I have to Pump the Gas to get it Going. After about 5 Minutes it Runs Better but still has a Miss Kinda jerky. After about 10 Minutes it Runs Fine. If Your Just Going to the Store for a few Minutes its Fine, But if You let it sit for like an Hour it Does it again but not as Bad as the Morning, And sometimes Theres a Smell . Not sure What to do. My Brother in Law Thinks its the injectors if so wouldn't it do it all the Time. THANKS
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Old 12-08-2014
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Your engine is fuel injected so pumping the gas pedal doesn't do anything.

What you can do is the "Clear Flooded engine" routine to see if you have a leaking injector.
Turn key on, count to 3, turn key off, this primes fuel system one time
Turn key on again, so you have primed it twice
Press gas pedal to the floor and hold it down all the way, this turns OFF fuel injectors, but spark stays on
Now crank engine, if shouldn't fire not even once it should just crank.
If you release the gas pedal at anytime injectors will start again.

If engine fires at all during the test you have a leaking injector, only place fuel could have come from.
Well, there is one other place but unlikely, at the end of the fuel rail is a Pulse damper, it has a vacuum line attached, remove this vacuum line and smell it for fuel, if there is fuel in the line then Damper is bad and that is your fuel leak.

Where is the "smell" noticed, engine bay, cab, exhaust?
It it a sweet smell or a fuel smell?

Couple things can cause rough cold start.
You could have a bad spark plug, how old are they?
A failing spark plug can work after it warms up.

Coil pack could be failing, again temp changes can make it an intermittent problem, but usually these show issues after warmed up not when cold.

ECT(engine coolant temp) sensor, this is a TWO wire sensor used only by the computer.
(not to be confused with the ONE wire sender used by the dashboard temp gauge)
The ECT sensor sets the Choke on a fuel injected engine.
When you turn the key on one of the first things the computer does is to check the engine temp, so the ECT sensor.
If ECT sensor shows 50degF then computer will run engine rich with high idle and advanced spark timing, so Choke mode.
As ECT sensor reports warmer engine computer leans out fuel and lowers idle.
If you start an already warm engine, ECT shows 180degF then computer runs normal lean fuel and low idle, 700-800rpms.
So if ECT sensor is failing and never falls below, say 100degF, then computer isn't running engine rich enough and you could get missing until engine really warms up.
If ECT sensor fails out right then you would get a CEL, warning light, but computer doesn't know if truck has been off for 10 minutes or 10 hours, it just goes by what the ECT tells it
ECT sensors rarely fail, not never but rarely.
These are easy to test with volt or ohm meter.

Worse case is the start of a head gasket leak.
But you would shortly start seeing some over heating

Last edited by RonD; 12-08-2014 at 12:49 AM.
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