Alright here's my story, on friday afternoon when i was on my way to work, my cel came on and the car started missing really bad and was running like a john deer, only without as much power....Well I got to work and parked it, When i got off I started it up and the cel was still on but it was running normal again. Saturday morning my buddy came over and pulled the codes and along with 5 missfire codes was the crankshaft position sensor code. So I ordered one up from autozone. Sunday morning I go pick up said part from autozone, and after a few minutes I get the thing in and reconnect the battery, fire it up, idle it, rev it a few times and everything was great no cel and it was fine....Sunday night i go get in the car fire it up and back it out of the garage, take off down the street and it stutters really bad in first, hmm that's odd...I turn onto the main street and it does it again, I get to the stoplight and take off at the green and bang it stutters really bad, the cel comes on, and the car dies out.....wtf!! I coast of to the side of the road and put the go arounds on, and try to restart. It fires right back up and i go to turn around and head back home and it goes about 10 feet and it shutters and dies out again. Restarts right back up, rev alttle and dies.....Always restarts but as soon as its reved past 2k rpms it dies out. Finally managed to limp home, all of 3 blocks, in first gear with it dieing out every 50 feet or so. Pulled back into the driveway and there it sits, i'm out of ideas everything that i read on here said that it sounds like the crankshaft position sensor is bad.......but i just spent 60 bucks and put a brand new one in???? Anybody here have any thoughts? Sorry for the long post i hope i didn't bore anyone to badly....

 

In all honesty it might just be low voltage in an old battery.
Enough power to start the car but not enough for normal functions.
When batteries start to die in these cars all sorts of strange things start to happen.
What year is your Crossfire and does it still have a White Battery in it ??

 

Its an 04 with 56000 on the clock...and yes it still has the stock white battery in it

 

Just went out and checked the voltage of the battery, its showing 12.6v....

 

Were there any codes for the MAF sensor? A bad or dirty MAF sensor can cause those symptoms.

 

Not the first time i scanned it, i haven't been able to scan it again after i replaced the sensor yet,

 

OMG! Do NOT pass "go", do not collect $200, don't even throw the DICE until you change that battery. The "steady state" or "no load" voltage does not matter in this discussion - change your battery.

I'll spare you my story of an old battery, but it cost me a tow and a $90 garage fee on top of that.

You have asked for help - here is some advice: Read post #2 again, and change your battery.

 

This battery at that age is most probably really weak, the electrolyte is probably way down as well.
Put some distilled water in it if its low, fill it up to the bottom of the six fill holes. Check the cables for corrosion and check the grounds.
A weak battery will put out 12 volts or so as long as all cells are still working but the amperage can be low. Have the battery tested under load at a battery seller.
I would suggest that you get a new battery anyway.
These OEM batteries are low maintenance, not maintenance free as they do have the fill holes. After 50,000 miles and six plus years this battery has served you well, say 'goodbye and thanks' to it.

 

I asked this once before - why does a good or bad battery affect anything when the alternator is running? Is low battery voltage when the engine is off supposed to affect something permanently? Seems odd Waits to be shouted at..............

 

No Shouting Look After Working On Electric Lift Trucks For More Years Than I Want To Remember I Remiss. The Alternator Is There To Charge The Battery Not To Give A Constant Even Supply Of Volts Or Amps. The Battery Is The Constant Even Supply Of This. The New Electronic Car Has To Have Even Consistant Volts And Amps And The Alternator Does Not Do This The Battery Does. It Is That Simple Unless You Make It More.

 

I'd like to thank everyone for there help.....I went out this morning and fired it up and decided that i'd put the old crankshaft sensor back in to see what would happen....thinking to myself maybe i got another bad one.....WRONG!!!....With the old one back in i fired it up and back out of the driveway it seemed to be running ok so i went around the block a few times and it seemed all good so i pulled out onto the main road and ran it through the gears alittle. I got to about 4th and all of a sudden it just stoped accelerating. I coasted back into the subdivision and eventually to a stop but the car was still idling????WTF!!! I hit the gas with the clutch in and nothing happened, hit it again still nothing, now i'm getting concerened that this car is about to go all Toyota on me. I turn it off and right back on and everything is back to normal and drive it home. Well being at the end of my rope I decide that i'll try the hole battery situation....So I took one of the extra optima yellow tops that I had in the garage and hooked it up.....GOD DAMNIT if it has been running like a champ for 75 miles without even a hiccup, no cel, no problems at all. All i gotta say is i'm sorry i didn't listen to you guys sooner......Thanks again to all that gave me a hand in this, and sorry for another long post.

 

But doesn't the alternator supply a fairly constant regulated 13.8 volts as against the batteries full charge of 12.8? Not saying anyones wrong just don't understand what is happening when you replace a battery - other than you disconnect the old one and maybe reset things?

 

Look A Battery Is Smooth Constant Dc. Alternator Is Ac Converted To A Not Smooth Dc. Fine For Charging Battery But Not For Supplying Voltage Amperage To Electronics. If You Would Like To Know More They Have Electronic Classes On Dc Ac .

Key To This Is Smooth Straight Line On Scope Dc.
Wavey Line Ac On Scope.

 

so when the car is running on a good battery it only runs off the battery not the alternator?

 

Look I Am Not Going To Debate You This Matter Is Closed For Me

Thanks

Otis

 

The way I see it and I may be completely wrong is that the battery buffers the voltage from the alternator which puts out a varying voltage. The problems arise with the voltage swings between the high of the regulator and the low put out by the failing battery, the voltage swing is what causes the problems.
The alternator puts out an AC voltage and the regulator only uses a portion of that, in essence only using flashes of some of the voltage output on the positive side of the curve.
The result being that the voltage available is a high of 13.8 V from the alternator and a ideal low of 12.8 V from the battery with the battery buffering this to a more uniform voltage.
When the battery is failing the swing would be higher, and this would create the problems. Some systems I suspect can work well on a greater voltage swing but others cannot.
The battery stores power, if you had a setup whereby you tried to start your car from the alternator alone it would not have anywhere near enough power to turn the starter motor, the battery stores power and is capable of releasing it in an instant. The alternator takes some time to replenish this power, but the battery can store enough to use the starter time and time again.
The amount of power that the battery stores is dependent on the number of plates in it, less plates in each of the six cells gives greater storage but less cold cranking amperage. More plates in each cell gives a higher cold cranking amperage but will get flat quicker due to less power storage.

I'm sure there are whiz kids who can rip apart my ideas, so go ahead please, I'm always willing to learn. If my errors are corrected then we all can learn.

 

Yes I think it probably is

 

As a lot of the electronics are Merc stuff I wonder if they suffer from the same voltage instability problems? I've driven plenty of cars which I couldn't turn off due to a completely dead battery but they were admittedly ancient fossils I've always assumed that they ran completely off the alternator when the engine is running. Makes me think that the cure of a replacement battery may well work but not actually be the total cause of the electrical gremlins. Having said that I'll be off to get a fresh one the minute it plays up
I'll stop now wouldn't want to upset anyone else

 

Hi All,

As an old time mechanic I learned that once an engine is running the battery is out of the running circuit. It is only being recharged once the engine is running. The electrical load is transferred to the alternator and the voltage regulator (now built into the alternator) steadies the voltage to the vehicle.
As we moved into the more sophisticated electronic systems the voltage to the computer became more critical. Therefore when the battery goes bonkers (sulfates and such) and the voltage it's drawing from the regulator is changing, the regulator is giving electrical surges or just not enough voltage into the once stable system. Depending on the amount of voltage spiking it will affect different systems through the computer.

We used to diagnose the battery vs alternator by simply removing the battery cable from the battery once the engine is running. If the engine continued to run the battery was bad if the engine died the alternator was bad (Yeah troubleshooting was much easier on my '70 SS 396). With todays electronics and delicate computers I don't recommend that, but the basic theory still applies.

The best test is a load test on a battery, not a voltage check. The voltage check does little to tell you the condition of the battery. A load test begins to tell you about the battery. You can go further to find out why the battery is bad, but if its bad...its bad. Replace it.

As a side note it isn't just Crossfires that have the problem. My daughter's Honda Hybrid was doing all kind of weird things and the dealer was going the wrong way with it. I had her replace the battery and guess what? Yup all the weirdness went away. I got a refund for their incompetence.

Sorry for the long dissertation. But I learned along time ago to not overlook the simple things and why they work, they can drive you nuts if you over think the situation. BTW electrical diagnosis was my speciality as a master ASE auto tech.

Rick

 

thanks for that - it makes a lot more sense. I guess a failing voltage regulator on the alternator would give the same effect, and fitting a new battery might cure the problem - but possibly only temporarily?