Alternator

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Ulver

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2001 Ford Expedition owner here. I've noticed that sometimes when stopped in idle, with my A/C on, the RPM gauge fluctuates along with the power/lights for everything else in the system. Note that this doesn't always happen when my A/C is on. Very much so an intermittent issue.

I hooked my DMM up to the battery, cranked the engine and turned everything on. Headlights, Max A/C, radio, etc. It's reading around 13.6. After that, I pressed down on a couple of power window buttons, and as soon as I did, the voltage dropped even more to about 13.1 volts.

So I can confirm that it's on it's way out. I have a new alternator, however I wonder if I should wait a while before I swap it since it doesn't seem severe?
 

1955moose

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Depends. If your just doing local trips close to home, you'll be fine. If yours is like mine, you'll see the charging gauge going down, down as your driving. When that happens, time to head for home, put the charger on the battery, and pop the new one in. Obviously if your a long day tripper, swap it out now.

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stamp11127

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If you did that test at idle the alternators output is about 25% of rated max. Try again at 2500 rpm and see if there is a difference. For a true reading of the alternators performance you also need the amp output along with the voltage. As the battery charges up the voltage regulator will alter the volts and amps as needed.
 
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Ulver

Ulver

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Thank you for the input gentlemen. Surprised that I actually had some free time this weekend, I finally got to an intake manifold job I've been meaning to do for weeks. And since removing the alternator is one of the steps, I went ahead and replaced it. The power is way better now and doesn't "dim out" anymore.

Now to solve this cylinder 3 misfire...
 

1955moose

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You might want to do an old school compression test on #3, since your yanking the intake, pulling the plugs are easy. Sometimes a misfire is due to a valve or ancillary components.

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Ulver

Ulver

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You might want to do an old school compression test on #3, since your yanking the intake, pulling the plugs are easy. Sometimes a misfire is due to a valve or ancillary components.

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Edit for the 50th time.. Lol. Still haven't woken up yet.

Hey Moose. I had already changed my intake gaskets by the time I made my last post. As a matter of fact, I feel like the intake job I did had something to do with this misfire. I tried to be as delicate as possible with the wires while taking the intake out, but sometimes it's hard not to. Also, I could have damaged the COP when I popped it out of the plug hole and tossed it.

So I think I do need to perform a compression test. I'm still getting a misfire (blinking engine light) this morning after changing out one spark plug and inspecting the boot and coil spring last night. Didn't do any test with the COP itself.

I also did a fuel injector swap to see if that would change anything.

Another thing is that I found a rubber o-ring inside of the spark plug well just loosely hanging out, seeming to serve no purpose, so I removed it with a hanger.
 
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Ulver

Ulver

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I just did a COP swap between the misfire #3 and the good #2 cylinder. I'll be driving it later on today. Hopefully the problem moves over. If not then I'll check wiring and connectors.
 

1955moose

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The loose o ring sounds like maybe from a nearby injector that you or previous owner changed. A blinking CEL is usually something major, like coil, or valve. Softer ones trip the light, but don't blink. Surprised it's not running worse than your saying. We've had a few members that had bad cats causing a single cylinder misfire. Something to look into, if the other items don't improve your problem.

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Ulver

Ulver

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I bet. I wouldn't doubt one bit that a cat is shot. I have a code (well, not right now since I've disconnected the battery for repairs) saying Catalyst System Efficiency Below Threshold Bank 1, and I know that the owners before me had this issue as well as a lean condition, because they didn't pass emissions, and I read their previous inspection. Why did I purchase the vehicle some people ask.. I needed something quick and accepted adopting the issues.

So going back to the misfire.. It just seems so strange that this happened right after I changed the intake gaskets this past weekend. I think I rattled something up in the process.

Also the blinking check light is intermittent. Seems to have happened when revving high on the highway. I slowed it down and put it into cruise control, and the blinking stopped.

Thank you for the reply. I'm honestly kind of worried, but as many things as to how they're perceived- it's not always as bad as it seems.
 

1955moose

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You'll figure it out. I'd run a smoker through the large hose that attaches to the brake booster. You'd be surprised where smoke comes out of, exposing intake leaks. Theirs a lot of spots on these vehicles that can cause an intake leak. You've got one of those cars I used to tell my customers, I need to fix one problem to find another.

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