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HDGENE, Ford Senior Master/Diesel/Trans
Category: Ford
Satisfied Customers: 5581
Experience:  25 years Auto experience, Ford ,GM, Chrysler, Asian & European
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Like all 5.4 triton engine mine idles so rough at slow down

Customer Question

like all 5.4 triton engine mine idles so rough at slow down or stop that it sounds like it is going to blow up. I have read every blog concernng this problen and no one has a solution.
JA: Is the rough idle intermittent or consistent?
Customer: intermitwnt. seems worse when engine is normal temp
JA: What year is your MiniE?
Customer: its a 2004 f150 5.4
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: channged the low idle sensors on both banks of engine, new filter, new gas filter and clening outside of throddle body.
JA: Anything else you think the mechanic should know?
Customer: nope
Submitted: 11 months ago.
Category: Ford
Expert:  HDGENE replied 11 months ago.

Hello, do you mean you replaced the oxygen sensors? How many miles are on the truck?? How does it run while driving? Just a poor idle? No warning lights on? ANy diagnostic trouble codes stored?

Customer: replied 11 months ago.
not oxygen sensors, these sensors were on front of valve cover. that is what the coder said was wrong. truck has 105,000 miles. It seems to run okay when driving down road. it still gets 16.5 to 17 mph on long trips. sometimes I can just tape gas peddle and it will idle normal others times it just idles rough and stops. no warning lights ever.
Customer: replied 11 months ago.
mpg not mph
Expert:  HDGENE replied 11 months ago.

Ok you replaced the VCT solenoids? Or the camshaft position sensors? What were the code numbers?

Customer: replied 11 months ago.
can"t remember code number. i did the replacement a year ago.
Expert:  HDGENE replied 11 months ago.

Is the check engine light on now? DId you remove the valve covers to replace these sensors, or pop them off the front of the timing cover on the front of the engine on both sides?

Customer: replied 11 months ago.
the check engine light is on and I replaced the sensors on front of timing cover.
Expert:  HDGENE replied 11 months ago.

Ok but that was a year ago. So with the light on now, the first thing that needs to be done is a check for what codes are stored now. Most auto parts stores will check for codes for free. If it has to do with cam position, either P0340, P0012, or P0022 it is most likely to do with either the Variable cam timing solenoids or camshaft phasers. So you need to pull codes first. Assumign there is no vacuum leaks, this could cause a poor idle and noise.

Customer: replied 11 months ago.
thank you
Expert:  HDGENE replied 11 months ago.

You are welcome, If it sets these codes, the first thing to do would be to remove the valve covers ( to gain access for the vct solenoid) and inspect the internal engine condition. If it is heavily sludged up/not maintained well this can be a bigger problem. the VCT cam phaser setup is operated off of engine oil pressure. So if there is a restriction, it will affect its performance. Also as you get into this mileage range, the timing chain can start to stretch or the chain guides can break. Worse cse scenario is an engine replacement, due to a lack of oil pressure. Major is timing chains, guides, tensioners and phasers, minor is the vct solenoids which would be the first route to replace if the engine looks clean. If you need more help let me know. If I was helpful, please leave a positive rating.