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Old 08-28-2018, 12:12 PM
Redranger45 Redranger45 is offline
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Default Misfires on start up

My truck has an ongoing rough idol on start up. Engine rebuilt a year ago. New plugs, wires, coil, tbps, all new o2 sensors, egr, cat, IAC.

Next moves.

Putting on new coolant temp sensor, replacing fuel filter.

Questions
I took wire off IAC. Truck rpms drop drastically. Does that prove no vacuumed leak or should I go to smoke test?

Fuel pump has 300 thousand miles but seems to hold pressure at 57 while running. Should I just replace fuel pump as it is so old?

Check engine light keeps coming on p0301 and p0303. But runs smooth after a few minutes. Seems smooth on road.

What next?
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1999 Ford Ranger XLT 4 door, 2 wheel drive, 6 cylinder 3.0 flex fuel engine with ac.
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Old 08-28-2018, 12:57 PM
djfllmn djfllmn is offline
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Default Re: Misfires on start up

Before you reload the parts cannon...
check to see WHY it is misfiring, proper spark, compression, fuel flow? If it goes away after the engine has some heat in it, could mean a loose head or something similar..it expands and seals back up again
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Old 08-28-2018, 01:01 PM
KenHigg KenHigg is offline
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Default Re: Misfires on start up

If you have a dpfe that could cause an idle issue. One way to test egr system is to dis-able the solenoid by unplugging it. You're not supposed to get egr gases at idle...
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Old 08-28-2018, 01:02 PM
djfllmn djfllmn is offline
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Default Re: Misfires on start up

Quote:
Originally Posted by KenHigg View Post
If you have a dpfe that could cause an idle issue. One way to test egr system is to dis-able the solenoid by unplugging it. You're not supposed to get egr gases at idle...
should have DPFE
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Past: 16 F150 5.0, 14 F150 5.0, 07 F150 5.4, 03 Ranger 4.0

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Old 08-28-2018, 01:12 PM
Redranger45 Redranger45 is offline
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Default Re: Misfires on start up

Ok. I just did smoke test with a cigar. Smoke is coming out of the round cap on top of the IAC. Not suppose to do that? Right? I have the old one and will try switching out. That I would assume is a vaccine leak?
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1999 Ford Ranger XLT 4 door, 2 wheel drive, 6 cylinder 3.0 flex fuel engine with ac.
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Old 08-28-2018, 04:32 PM
KenHigg KenHigg is offline
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Default Re: Misfires on start up

vaccine leak

Can you post a pic?
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Old 08-29-2018, 04:46 PM
Redranger45 Redranger45 is offline
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Default Re: Misfires on start up

The engine rebuilders tested the compression and said it was fine. Fuel pump holds steady at 57 lbs. All new motorcraft fuel injectors.

I just put in a new coolant temp sensor and check engine light has not come back on. It has a new EGR sensor and I will test the dpfe sensor. Fingers crossed check engine light does not come back on. Thanks!
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