effects of broken alternator

[sneaky7980]

Just wondering how an inop alternator would affect engine performance other than not charging your battery.

[dksob81]

well your jeep wouldn't run if the altenator wasn't working.

The alternator runs all the electrical effects of the enigne. All the battery does is give everything power when the engine is not running.

[sneaky7980]

My jeep idles very rough and has very poor throtle response, it will die if i just barely get on it. I decided to check the alternator output thinking it could affect the ignition system. unless i checked it the wrong way, i'm showing 0 volts. below is a list of recently changed items, i'm running out of ideas at this point!

fuel pump
" filter and regulator
ignition rail and plugs
cam sensor
injectors
water pump
checked TPS, IAC

BTW it didn't run at all until the pump was changed, now just runs like crap

[Bob D.]

Originally Posted by dksob81

well your jeep wouldn't run if the alternator wasn't working.

The alternator runs all the electrical effects of the engine. All the battery does is give everything power when the engine is not running.

dksob81, I don't think that's right, at least from my experience.
The battery supplies the vehicles electronics with power, the alternator just keeps the battery charged.
Your car should run for a while with a non functioning alternator, until the voltage drops below what's needed to charge the coil and run other essential electronics.
Then the engine would start to run rough or quit altogether.

sneaky7980, if you keep replacing parts you're going to have a brand new Jeep soon.
You can also tell If your alternator is bad by measuring battery voltage with it running...it will fall like a rock if its not constantly being charged.

[dksob81]

Originally Posted by Bob D.

dksob81, I don't think that's right, at least from my experience.
The battery supplies the vehicles electronics with power, the alternator just keeps the battery charged.
Your car should run for a while with a non functioning alternator, until the voltage drops below what's needed to charge the coil and run other essential electronics.
Then the engine would start to run rough or quit altogether.

sneaky7980, if you keep replacing parts you're going to have a brand new Jeep soon.
You can also tell If your alternator is bad by measuring battery voltage with it running...it will fall like a rock if its not constantly being charged.

Well your right about the electronics and engine running for a lil bit if the alternator is bad, it will run for a minute or so (on a fully charged battery) until the battery power is all use then it will die.

The way to test an alternator to see if it is operating, is to start the jeep let it run for a few minutes then disconnect the battery (negative cable, but disconnect both for the heck of it). BOB D, try this you will see that you engine will continue to run without the battery connected.

Now, a poorly operating alternator will cause some stalling at idle but while driving it will continue to run, because at higher engine speeds it is actually giving off enough juice to keep everything running, but at lower speeds it is not. I just went through this with my cousins car, she could drive on the highway for a half an hour but as soon as she would stop (at stop light or so) it would idle for a few seconds then die and would have to jump the car because the battery was dead.

[teemsta]

put in a new coil and see what happens. my 94 5.2 had the same symptoms as yours. about a month after a tune up it started to idle rough and if I stepped on the gas it would stutter and go and stutter. I changed the tps and iac and nothing changed. then I changed the coil and after I did that it ran like new.

[Tomsriv]

The correct way to check the alternator is to hook up a volt meter. You can get them for as little as $10. If the alternator is working correctly you will have 13.5 to 14.5 volts at the battery with the engine running.

Disconnecting the battery with then engine running will cause voltage spikes and can damage components.

[dksob81]

i wasn't saying disconnecting the batt was correct way to test the alt, i was just saying u can disconnect it as a quick test. if it continues to run then the alt is fine.

i dunno know about it hurting anything tho, i have done this many times and never done any harm, plus the system runs off the alternator anyways when the engine is running, not the battery.