Car is acting extremly weird and is undrivable Help!

[mat82284]

I have never come across this issue, nor know what to do to fix it.

I just left campus after studding with some friends and i went to drive my car and it wont move. It starts, but as soon as i put the car in gear it dies. The car revs fine, even to 5000-6000rpms and sounds normal. The battery gauge moves up and down. When i turn the head lights on my car dies. When i flip the switch my cluster gauges move from 0 to 150mph and back. All the gauges do this, but every time the car starts!

The car was acting a little weird when i first arrived to campus. It was idling up and down and wanted to die. I just parked and went in side. I checked the volts at the battery and its reading 12.5v and when the car is idling its reading 13.9v When the car rev's its 14.0v. I thought maybe the alternator but if its getting that high of voltage it cant be. Could a bad battery somehow cause this? Maybe my battery is bad, yet it still holds a charge and allows me to start my car?

I'm completely stumped on this problem. If you have any incite as to what it could be please respond to let me know.

The only reason i suspect the ECU is once its in gear it dies. I have a SCT livewire and can log, if its suggested that i log please specify what. Also I checked for codes and there is none.

 

[trinity_gt]

I would check the integrity of the battery cables and grounds first. Make sure everything associated with the battery is tight, clean and corrosion-free. This includes the terminals themselves and any grounds to the chassis nearby.

It may be that the battery is on the way out but it's cheaper and easier to check the simple stuff first.

 

[Brute03]

+1 on checking the terminals. my guages used to sweep on start up and all sorts of other craziness, turns out the ternimals were corroded.

 

[mat82284]

+1 on checking the terminals. my guages used to sweep on start up and all sorts of other craziness, turns out the ternimals were corroded.

I checked all the terminals and its all on really tight. Im thinking of taking my battery to kragen to get it checked since its less than a year old and its under warranty. Could any fuse cause this? maybe the ecu? If the ecu was going bad how would one know? would it just not start?

 

[joshjwc9]

More than likely it is the battery, but if it checks out it could be the alternator that is not charging up the battery to full strength when your car is idling.

 

[mat82284]

More than likely it is the battery, but if it checks out it could be the alternator that is not charging up the battery to full strength when your car is idling.

See the thing about that is that the alternator is outputting 13.9v and 14.4v when cold. I cant see it being the alternator. Its a 200amp alternator as well. I checked with a volt meter and the power from the alternator is 14v. I checked the battery and its 12.5v

The only thing i can think of is that the battery somehow went bad to where its steeling all the alternator power from getting to the car. I'll check the battery today after class and the alternator that way i can ween these out if these are not the issues. I'll test the car with the negative off today to see what happens as well.

Like i mentioned before, the car starts up, Idles fine, and even revs up fine. I even held the rpms at 4k for 1 min and it seems good, but as soon as i put it in gear and started to release the clutch thats when it died.

but my main question though, if a computer is malfunctioning could it cause power fluctuation like this which cause the car to die?

 

[GettinThere]

The car was acting a little weird when i first arrived to campus. It was idling up and down and wanted to die.

Easy to check for a vacuum leak, if nothing else to rule it out.

 

[mat82284]

Easy to check for a vacuum leak, if nothing else to rule it out.

I have checked for all possible vacuum leaks, but i have ruled that out because of the car idling and being able to hold at 4k for 60 seconds without any issues. In a few hours ill be able to test out the battery. I'll report back when I'm done. If its not the battery or alternator the only suspect is a wire got to much current and started to fall apart somewhere in my car. Or my ECU got to hot and burnt up a transistor or something that is causing a power fluctuation. I just wish there was an easy way to test the ecu without actually buying a new one, since you cant return any electronic parts to the dealer.

 

[mat82284]

Just wanted to give everyone the heads up that my battery tested fine, It was actually the negative terminal. The wire at the tip near the negative terminal somehow burned. The bottom of the wire was showing and there was alot of crud all over them. I cut the wire shorter put new terminals on and it works like new.

This was a weird experience, but im glad it was a simple fix.

 

[GettinThere]

Thanks for the follow-up. Glad it was something simple.

 

[trinity_gt]

Just wanted to give everyone the heads up that my battery tested fine, It was actually the negative terminal. The wire at the tip near the negative terminal somehow burned. The bottom of the wire was showing and there was alot of crud all over them. I cut the wire shorter put new terminals on and it works like new.

Good to hear it was something simple.

The "burning" you describe can likely be explained by the corrosion. As corrosion sets it, there are less conductors and less surface area to carry current (especially the hundreds of amps required by a starter motor...) The result is an increase in resistance which subsequently causes an increase in heat. As the corrosion worsens, the heating worsens. Soon the resistance gets so high and the contact so tenuous that you start seeing overt evidence that something is really wrong (e.g. gauges swinging etc) but by that time, you've likely got evidence of heat damage too in the area of the breakdown.