re: F-150 "Reduced Engine Power" warning

I may be the next one

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Got this on the way home from the gym this morning. AC quit blowing cold air and the temp gauge maxed out. 2007 F-150, 5.4L V8. Stayed like this for about 5 minutes then everything went back to normal.

engine has been bucking in the 55-60mph range recently so i was planning on changing spark plugs this week, but is the above warning indicative of a larger problem?

nb4 ford jokes

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You probably have a misfire. DId the check engine light come on? The PCM is programmed to shut the a/c off and go into reduced power mode in the case of a misfire to allow you to get home without damaging the motor. You almost certainly have at least one ignition coil that has gone bad. Those motors are notorious for that. Coils are around $75 each you have one on each cylinder. If you're mechanically inclined at all you can replace them yourself, they aren't very hard to change, just the back ones are hard to reach.

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yeah, gotta take off a lot of shite to actually get to them. my biggest fear would be breaking the plugs. former mechanic buddy is helping me out, shouldnt be too bad

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LOL it's a tri valve? Those are a nightmare to change plugs on. There is a reason Ford gets $600 to do the job, plus $50 for each plug they break.

Seriously at 150K miles, the truck is overdue a tune up and you probably have a bad ignition coil. you may even have a plug that has blown out of its cylinder, those motors are bad about that, BUT usually you'll hear a knocking noise if that is the case, and no that isn't a major problem, but you will have to take it to a shop that has the tool required to repair it.

Stop being a poor and just buy a new king ranch

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It's usually not the coil pack but the boot or spring inside the boot that causes the misfire. Cleaning the contact on the coil pack and replacing the boot and spring is less than $2 in parts. Shops/mechanics usually install a new coil pack that comes with a new boot and spring.

I have logged over 450,000 miles in my last 3 F150s and never had a coil pack fail. I do replace the boots and springs when I change the spark plugs.

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Good point, THose tri valves are terrible about the boots shrinking up, then what actually happens is moisture gets into the cylinder and when the engine fires, the moisture creates a misfire condition.

You CAN just replace the boots, but usually it's just easier to replace the coil. One thing is for sure, ANY time you do a tune up on these engines, spend the extra $20 and replace the boots on each coil.

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ford

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Thanks for all the advice. May just bring this mfr info the stealership and let them frick with it

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Thanks for all the advice. May just bring this mfr info the stealership and let them frick with it

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Gotta find a reputable independent auto tech. This is almost without question a misfire. I know the a/c has thrown you off, but that is by design, not the result of a bigger problem.

And the 4.6/5.4 engines are notorious for bad ignition coils. It's just a matter of which one, or you could simply replace all 8, but that gets expensive. Any mechanic that has a quality commercial grade scanner can pinpoint which cylinder is misfired and get your problem sorted out.

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You probably have a misfire. DId the check engine light come on? The PCM is programmed to shut the a/c off and go into reduced power mode in the case of a misfire to allow you to get home without damaging the motor. You almost certainly have at least one ignition coil that has gone bad. Those motors are notorious for that. Coils are around $75 each you have one on each cylinder. If you're mechanically inclined at all you can replace them yourself, they aren't very hard to change, just the back ones are hard to reach.

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That won't explain the temp gauge. If it moved quickly up and quickly fell back to normal I would think about the temp sensor. That would explain a lot. CEL? I would have it scanned for codes and misfires. Would tell a lot.

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That won't explain the temp gauge. If it moved quickly up and quickly fell back to normal I would think about the temp sensor. That would explain a lot. CEL? I would have it scanned for codes and misfires. Would tell a lot.

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Of course it needs to be diagnose, I'm just giving best guesses based on experience.

But yes, a misfire can explain the temp gauge fluctuating, at least until the PCM does as it's designed to do and shuts down the a/c and reduces power to prevent overheating.

I'm fairly confident that this is a bad ignition coil at worst, but at 150K the engine just needs a tune up anyway if it hasn't had one in its life.