2002 Ford Explorer XLT 4.0 Rough Idle at Times...

[Andy1416]

Hi everyone:

My 2002 Ford Explorer has a rough idle at times and I don't know why. My plugs, wires, and ignition coil are brand new. Also my air, fuel, and oil filter are quite new. Does anybody know what the problem could be, it's driving me a little nuts.

 

[LMHmedchem]

Have you cleaned your throttle body lately? A dirty throttle body is a possible cause of rough idle.

If you haven't done it in a while, it's a good idea to give it a good clean and to also clean you mas airflow sensor at the same time. It's very important to use a specific throttle body cleaner to avoid damage to your oxygen sensors. Only use a specific MAF sensor cleaner as well.

CRC 05078 Throttle Body and Air-Intake Cleaner 12 oz ($10)
CRC 05610 Mass Air Flow Sensor Cleaner 4.5 oz ($11)

You can get a pack with a bottle of each but the bottles are small and single use.

CRC Mass Air Flow & Throttle Body Single-Use Cleaner Twin Pack Kit ($8)

There are lots of videos on how to do this if you haven't done it before. After you do a good cleaning, you can also run a can of SeaFoam through the upper engine.

LMHmedchem

 

[TechGuru]

Clean the MAF and IAC.

 

[tedmc1]

Any codes? Check the vacuum hoses near the rear of the engine..esp the one that comes out of the intake right after the throttle body.Mine were all hard and cracked. I was getting rough idle and P1151 until I fixed the vacuum lines.

 

[Josef161]

Hi everyone:

My 2002 Ford Explorer has a rough idle at times and I don't know why. My plugs, wires, and ignition coil are brand new. Also my air, fuel, and oil filter are quite new. Does anybody know what the problem could be, it's driving me a little nuts.

Does it smell like gas around the engine? I've had a rough idle that was caused by old/hard fuel injector o-rings.

 

[Andy1416]

Ignore this message in this box.

 

[Andy1416]

Hi everyone:

My 2002 Ford Explorer has a rough idle at times and I don't know why. My plugs, wires, and ignition coil are brand new. Also my air, fuel, and oil filter are quite new. Does anybody know what the problem could be, it's driving me a little nuts.

I cleaned out the IAC, MAF, throttle body, and installed a new PCV valve and it still idles rough.

 

[Stynx]

With old engines like these all the rubber and seals start to go. In cases where the plugs, etc. have already been changed and it still idles rough, it makes me think vacuum leak.

 

[Fix4Dirt]

not sure bout 3 gen but on mine the intake gaskets like to leak, and also the Y on the iac like to do that too. not sure if it changed for gen3 rhough

 

[TechGuru]

My plugs, wires, and ignition coil are brand new.

What brand(s)?

Spark plugs need to be Motorcraft SP500.

Ignition coil should be Motorcraft/Denso/Bosch

Have you checked compression for evenness? Could have a valve leaking at idle.

 

[LMHmedchem]

Clean the MAF and IAC.

Did you clean the MAF? The airflow sensor should be cleaned along with the throttle body or when you change out the air filter.

Make sure you use the correct cleaning fluid if you do this.

LMHmedchem

 

[Andy1416]

Did you clean the MAF? The airflow sensor should be cleaned along with the throttle body or when you change out the air filter.

Make sure you use the correct cleaning fluid if you do this.

LMHmedchem

As I clearly posted I cleaned the IAC and MAF.

 

[LMHmedchem]

I cleaned out the IAC, throttle body, and installed a new PCV valve and it still idles rough.

You posted that you cleaned the IAC and the throttle body, not the MAF. Maybe you forgot to add it to the list?

Other than running a can of Seafoam through the upper engine you seem to have ticked all the boxes for cleaning. I am not sure that Seafoam would help a rough idle. If your spark plugs and coil are those suggested by TechGuru than a compression test may be the next step.

LMHmedchem

 

[Andy1416]

You posted that you cleaned the IAC and the throttle body, not the MAF. Maybe you forgot to add it to the list?

Other than running a can of Seafoam through the upper engine you seem to have ticked all the boxes for cleaning. I am not sure that Seafoam would help a rough idle. If your spark plugs and coil are those suggested by TechGuru than a compression test may be the next step.

LMHmedchem

I did clean the MAF too, my bad.

 

[Fix4Dirt]

also if you do a comp test check for excess carbon deposits, but i dont think it would cause an intermittent issue...

 

[Bookworm370]

Is it rougher when the engine is cold and gets better when it warms up? If so, that's a classic vacuum leak somewhere. The hose assembly from the PCV to the Intake is notorious for this. The bend right at the throttle body vacuum source is a classic fail!

 

[Andy1416]

It's when my engine warms up is more the issue. No codes get pulled up, when it's scanned. My PCV hose looks fine with no visible cracks,

 

[Andy1416]

What brand(s)?

Spark plugs need to be Motorcraft SP500.

Ignition coil should be Motorcraft/Denso/Bosch

Have you checked compression for evenness? Could have a valve leaking at idle.

Spark plugs are Motorcraft SP500. The ignition coil is a part from a brand based out of Florida. I checked for compression when my engine was going to get cylinder head work done to it and one valve was leaking at idle, and I got it replaced with a brand new Motorcraft one.

 

[Stynx]

Smoke test?