Rough Idle

[kleachy]

2000 Explorer Limited 5.0. 91k miles. Idles fine when first started... When gets warm I get a rough idle. No codes or lights. Changed plugs, Wires and tried another coil pack from another explorer 5.0 and no changes. The rough idle is not consistent. Any Ideas? Thank you !!

 

[jlrohio]

I'm just throwing out some other things to check... (Note: I have a 99 4.0 OHV engine - very different from your 5.0)

Idle Air Controller - Remove and Clean (plenty of video's online showing how to clean it) - move the piston thing back and forth inside. Do NOT get cleaner up in the motor part - make sure the open holes are always pointed down when spraying cleaner in them.

Throttle Body Intake - Remove air supply hose and clean that throttle body plate and intake area real good - use ONLY Throttle Body Cleaner - Do NOT use Carb Cleaner (you can use Carb Cleaner on the Idle Air Controller).

MAP Sensor (it's in the supply hose) - Clean it with MAF Sensor Cleaner (ONLY).

These three items - I just did today to address a low idle situation and it was like restoring idle and pickup back 10 years!

Oh, buy a new Air Filter if it needs it - depending on where you are - the pollen is just clogging that thing!

 

[kleachy]

I'm just throwing out some other things to check... (Note: I have a 99 4.0 OHV engine - very different from your 5.0)

Idle Air Controller - Remove and Clean (plenty of video's online showing how to clean it) - move the piston thing back and forth inside. Do NOT get cleaner up in the motor part - make sure the open holes are always pointed down when spraying cleaner in them.

Throttle Body Intake - Remove air supply hose and clean that throttle body plate and intake area real good - use ONLY Throttle Body Cleaner - Do NOT use Carb Cleaner (you can use Carb Cleaner on the Idle Air Controller).

MAP Sensor (it's in the supply hose) - Clean it with MAF Sensor Cleaner (ONLY).

These three items - I just did today to address a low idle situation and it was like restoring idle and pickup back 10 years!

Oh, buy a new Air Filter if it needs it - depending on where you are - the pollen is just clogging that thing!Than

 

[SofaKing95]

I'd add ECU temp sender to the list -- if the temp sender to the ECU isn't working the ECU will never go into closed loop and remain in open loop

Coolant temp sensor/sender causing truck to run rich?

Hello all, I've been trying to rectify poor idling and reduced power on my 1999 Ford Ranger xlt (3.0 flex fuel) for months now. As of now, the truck won't throw a code but long term fuel trim banks are hovering around -7.5, and it remains in a closed loop no matter how long I drive it...

www.therangerstation.com

As for IAC valve mentioned above, those usually present issues at start-up (cold) not after engine warmed up, key word "usually"

 

[kleachy]

Hello there... Tried all the above without success except ECU temp sender. Where is it located? It's a strange thing... the idle is sporadic and seems like a miss. Not at all a regular occurrence and having misfires - like 200 + in a 10 minute idle. New plugs, wires and coil packs. At wits end!

 

[410Fortune]

Have you tested your fuel pressure?

You have firing order correct at the coil pack?

Inspect the airbox / intake tube/ throttle body and instake for any air leaks?
Make sure the pcv valve is seated in its grommet (back of engine behind upper intake)
No exhaudt leaks at the egr valve?

The ECT or engine coolant temp sensor is on the lower intake manifold, under the coil pack tripod. The brown one with a single wire is for the dash (cts) the grey one on the left with two wires is the ECT sensor the one for the pcm

Before replacing it you can do a resistance test to it check ohms
You can also watch it work on live data and see if the pcm is switching when the water temp gets to 200

5.0 fuel rail 96-97 return style fuel (two fuel lines) 42 psi
98-01 returnless fuel (one fuel line) 64 psi

 

[kleachy]

I will have to look into these things.. Funny, no engine light.

 

[410Fortune]

Does the check engine light come on with the key?
We must rule things out and check things over often a flashlight is your best tool

 

[kleachy]

Yes it does. I will check my plug wires again... Maybe I am crossed somehow. I certainly have messed up a lot!

 

[kleachy]

Yes it does. I will check my plug wires again... Maybe I am crossed somehow. I certainly have messed up a lot!

just checked wires.. Was hopeful that was the culprit... not!

 

[410Fortune]

Can rent a fuel pressure tester

2000 5.0 should be at 64 psi
They will run decent with 36-40 psi but you will have issues like random misfires, loss of power.. must rule things out it is better to diagnose then just throw parts at it