Ask Experts Questions for FREE Help !
Ask
    gcjeter's Avatar
    gcjeter Posts: 2, Reputation: 1
    New Member
    		  
    #1

    Jul 7, 2010, 08:30 PM
    To high RPM's
    I have a 2003 F250 and I have not had much problems with it just recently my altenator went out on me and I had to drive the truck about 60 miles on just the batteries. When I got it home I put a new altenator in and now it runs good but it is running 1000 rpms higher than it should be. It usually would run 65 mph at 1800 rpms now 65 mph and its at 2800 rpms. I have no ideas. Can any one help?
    TxGreaseMonkey's Avatar
    TxGreaseMonkey Posts: 16,761, Reputation: 5597
    Uber Member
    		  
    #2

    Jul 8, 2010, 05:51 AM

    Here's what I would try:

    . Remove and fully charge the battery. Most auto parts stores will do this for free. Don't put the strain on your new alternator.

    . Disconnect the negative battery cable and clean the connectors to the mega fuse alternator cable with abrasive cloth. Afterwards, apply dielectric cable. Corrosion likes to develop, here. Also, clean the main negative ground and battery cable and terminal connections.

    The PCM is likely directing the engine and alternator (FR Signal) to run faster, in order to charge the drained battery. I know, for a fact, the PCM has this control over idle speed. The PCM compares the electrical load (ELD) signal with the FR (Charging Rate) signal from the alternator and uses that information to set the idle speed and turn the alternator on and off.
    gcjeter's Avatar
    gcjeter Posts: 2, Reputation: 1
    New Member
    		  
    #3

    Jul 8, 2010, 01:55 PM
    Comment on TxGreaseMonkey's post
    Thank you for your sugestion. After I installed the new altenator I did charge the batteries fully before I hooked them back up. I had to replace one of them. I guess I ruined it.
Not your question? Ask your question View similar questions
 

Question Tools Search this Question
Search this Question:

Advanced Search

Add your answer here.


Check out some similar questions!

Honda civic RPM's bouncing back and forth [ 1 Answers ]

I have a honda civic 1995. The cars tach is bouncing up and down. When it goes to 0 rpms The car stalls. There are no check engines lights. I cleaned the iacv valve, that did not work. A friend told me that it could be the ignition, because the tach is controlled from there. Is this possible? The...

RPM's from a 25cc weed eater engine [ 3 Answers ]

I have a weed eater brand,25cc engine and I need to know how many rmp's it has in the max amount and the minimum amount. I would like to know if the brand has anything to do with it or it just depends on how big the engine is. I will take any advice or help that I can get thanks.

High rpm's [ 1 Answers ]

I have a 98 ford ranger and have had a problem with rpm. I have a 2.5 litter 5 speed engine with a/c. When the outside tempature rises above 60 degrees I lose control of my rpm's. Rpm's will shoot way up and not come down to normal until I stop rolling. I have changed my idle speed control valve...

RPM's at 0, but car is on [ 1 Answers ]

I have a 98 honda accord, 4 cyl. On rare occasion, I will be driving my car, when all of a sudden I am no longer accelerating. My foot is on the gas, but my RPM's have dropped to 0. The car stays on this whole time, but I can't go. I have to turn the car off and then when I go to start it, it...

1979 Accord... rpm's drop at 55mph [ 4 Answers ]

What is happening is when I drive the car and I go to 55 or higher the rpms drop to 0 and then when the car slows down to 50 it comes back on. We changed the coil but that did not fix the problem. Does anyone have any ideas?

View more questions Search