Nichoms

Well I checked the alternator again with my multimeter. I could not reach my probe to the actual connector on the back of the alternator so I had to hook to the positive cable coming from the alternator connecting to the battery. I tried grounding to the battery, the alternator housing, the ground hooking to the strut tower, and the strut tower bolts; all with the same results, 12.5V.

I brought it to Oreilly's to have them check the alternator and they just hooked positive and negative to the battery and it read 14.3V.

So why would my mulitmeter read ~12.5V no matter how I connect and the Oreilly's machine reads 14V?

The crank sensor is dirt cheap and looks pretty easy to install so that might be the next option before bringing it to the dealership to pay for diagnosis.

Anyone have any ideas?

Nuke

Bad batteries (not DEAD) have been known to cause similar problems as a defective alternator. Have the battery load tested, since it may be loading down the alternator. And keep us posted.

Nichoms

I am at work so wont be able to get to it til later but I will pull the battery and have it tested on it own. Thanks for the idea!

And whenever I do eventually find out what it is I will post what fixes it... I have read through tons of threads where people are having misfire problems similar to mine but they never post what they did to finally fix it. Its like once they fix it they forget about the forum and never post the solution. Or maybe they never fix it....

atomicpunk

I don't know what kind of multimeter you have but do you have it on the right scale? My OTC multimeter has 4 different voltage settings.
As people have said already I would do a compression test on the engine before throwing more parts at it.

Nichoms

Ya I have tried the 0-20V and the 0-40V DC scales and they both read 12.5V. Its a reasonably new $50+ analog multimeter so I trust it.

Before putting any more parts into it I am going to check fuel pressure and do a compression test. My compression tester is for the bigger size spark plug so I'll probably have to rent the compression tester from the autoparts store.

Can I check fuel pressure accurately through the OBD-II? I have a cool app on my phone "Torque" that hooks up to OBD-II through a blutooth connector I can borrow from a buddy if it will measure fuel pressure; otherwise I will rent a fuel pressure gauge from the autoparts store as well.

Thanks!

JCON

ever fix the problem? My car is misfiring under 50%+ loads. Started after replacing the spark plugs. Regapped and it went away for a day then came back. So I started swapping an old one in and went through all 8 cylinders and it was the Cylinder #5. So I am running 7 new plugs and one old. Problem went away for 4 days and is now back. Today I bought a new COP and put it on and drove half an hour. Still misfiring under load. fine at cruising. No codes definite power loss when I hear it and feel it. AC still works too.

s197grl

Yes, any resolutions that anyone could offer? I have a misfire after replacing all pugs, coils, sensors, injectors, checking compression, checked the fuel pressure, new fuel filter, new fuel pump, new throttle body, new gaskets on injectors and manifold, also whole new VCT system, including, phasers, solenoids, chains, tensioners..the whole deal. MAF is new, installed that when I installed the JLT CAI, and yes its tuned, and yes I dumped this much money in this car..Ford doesn't have a clue, the misfire keeps jumping from cyl 4 to 8..odd. Any help or new ideas appreciated! sensors replaced, CMP,CKP,TPS, and yes I've checked the fuel relay. Altenator checks out clear.
Mods: Steeda underdrive pulleys, Steeda lowering springs, JLT CAI, JBA axle backs,Hurst short throw.
Sorry for the long response, just giving an idea of the crap I've been through..lol

moosestang

What code are you getting? You have to do a ripple test on the alternator, not a standard test. Place a digital voltmeter on the battery, with the car running, set to the lowest AC voltage. It should read very low, like less than .1 volts AC.

s197grl

Thanks for the idea, I will try that today..I have access to my husbands shop, so ill try anything that anyone throws out there! I'm getting only a P308 now..in the past I have gotten tons of codes but they have all been cleared and not returned. Its getting horrible gas mileage, seems to run rich, but no code for that at the moment.
The alternator was replaced about a year ago, that's why I haven't really dove into thinking that's the problem.
Thanks again Moose

s197grl

I am dealing with a misfire also, are the plugs and the COP the only thing you have done? What codes were you getting?