TheTransporter69

iTrader: (5)

My car is having a weird problem, about a week ago is when this started. I took the car on about a 150 mile round trip. It was fine down there but on the way back is when it started acting up. First thing I noticed was the speedometer jumping up when the two 12" subs would hit. I just shut the radio off after a while, but then the speedometers just off(said i was going 80 when only going 65, had a gps with me as well to tell actual speed). Then as I'm getting closer to home when i try to accelerate it would cut out and miss so i could only cruise with light throttle. The gauges were acting up now too (specifically the alternator amp gauge was all the way down) It gets worse so i got off the interstate and when i get to the stop sign it dies completely. We push the car off the road and it doesn't even turn over. I still had power to the gauges and radio i believe. After a while I'm having it towed home and once I get there we throw a power pack on the battery and i was able to drive it in to the garage.

I charged the battery for a while and the tow guy figured it was the alternator that went out. I took the alternator and the battery in and they both test good.

So today i pulled all the extra stereo crap out(subs and amp) and put it alternator and battery back in and go through and check the grounds that I know of(coil to frame, engine block pass side, and the one from the battery to the stud by the ps res.) They all look good so I started my car up. Its idling fine, but I rev it up some and i see the alt gauge go down and the gauge lights are going dim too. So I figure its loosing power somehow when its revving up. Now seeing that the alternator and battery are good Id assume maybe coil or opti going bad? I'm just not sure where to go from here or how to test them.

ugod02010

sometimes the alternator may seem okay, How many times did they test both the alternator and battery should have checked each one a few times. It may be an intermittent problem now, (works sometimes). The Lt's are extremely finiky when it comes to voltage or anything for that matter. Check out and make sure your belt is good and tight then run over the wiring again. Also could be your belt tensioner is going bad and isn't pulling the belt tight enough over the alternator to spin it as fast as it needs to to get a good charge..

http://shbox.com/1/4th_gen_tech1.html
the testing procedures for just about everything is here.

TheTransporter69

iTrader: (5)

i just did them each once, I could take it to another place and try again. The belt seemed pretty tight yet. but I'll check it over.

Could it also be opti or coil related failure? The opti is one from summit about a year old or so. Would they break up at a little over idle and draw power(alt gauge going towards zero)?

stevo9389

an out of control tach signal could be a sign of a bad opti or connection to the harness. since your other gauges were going apeshit, then i would go back to troubleshooting a power/harness issue and maybe add more grounds before it kills things like your opti.

ugod02010

Not real sure on that one. But like Stevo said try adding a ground. Put one from the battery to chassis, try it, next go to the head to chassis, check it, ETC..
It is possible that you are having problems with the opti/icm but it really seems like you have a wiring demon somewhere. And I would definitely have the alt/battery retested they should check it at least 3x..

shbox

You either have a poor connection or battery or alt is still bad.

TheTransporter69

iTrader: (5)

ok thanks guys

KW Baraka

iTrader: (7)

My vote is bad alternator.

Just went through this for the second time in 10 months....two different Impalas....

KW