Surging/ Almost Stalling On De-acceleration

[mike2002]

i just noticed this the other day. if im driving say 50mph and i let off the gas, the rpms slowly drop and drop, get below 1000rpm and the lights get dimmer. then it continues to drop to about 500 rpm, lights get really dim, then it jumps up to about 1100rpm, then back down, then up, back and forth untill i give it gas. when i do get the car stopped, it seems to idle fine, steady 800rpms. also, the lights dim really bad with music, even when the sounds down.

is this the alternator going bad? it seems like its getting worse, today comming home it was really bad, the lights got really dark, i thought it was going to stall. even with the radio off, it still did it.

[FormulaNERD]

might sound dumb, but feel the alternator, is it getting hotter than normal?

may be hard to tell i know, but before my alt went out, it was getting way hot.... like almost red hot.

[mike2002]

ill check it out next time i drive it, but i dont know how hot it usually is.

i know checkers will check batterys...do they check alternators?

[wy3134]

bout the only way i know to have an alternator checked is for your local GM dealer to run a full electronic diagnostic on the car, which costs about $70 or $80 depending on the place, maybe cheaper, maybe more.....

[BLK03GXS]

Put a piece of iron on the back of your alt at idle... if it sticks then usually thats a good sign that its charging.
At least thats what the old timers say :P

[smokinAMD]

Autozone will check your alternator for FREE. But yeah, I'd say yours is shot.

[mike2002]

can a mod move this to the common problems and troubleshooting for me, i just reliezed i posted in the wrong forum

[mike2002]

found out the problem, the guy at checkers told me to clean out the idle air control motor, a $2.69 can of brake cleaner later and it no longer surges or wants to die on de-accleration. a plus is, the lights dont dim nearly as bad as they used to when my stereo's up. i guess by cleaning it really good, the car can react to higher current draws faster and not dip in rpm's/dim headlights when bass notes hit. not a huge difference, but i notice my halo gauges dont dim as much.

[bluephoAm]

Where is the Idle Air Control Motor? That's new to me..
I want to check mine... or does the 4-cylinder even have one?

[mike2002]

i dont know where it would be on the 4 cylinder, on my v6 it was on the throttle body....i can take a picture tomorrow with the digital camera. is your car surging or not idleing steady?

[bluephoAm]

Oh okay. I just wanted to check it for preventative maintenence. No, it's steady except on a cold morning when it's trying to warm up.. it shakes a lot more when it's cold outside than when it's warm.