Rpms drop

[Josiahsgtp]

Any help for this would be greatly appreciated. When accelerating my car feels normal but occasionally when coasting or braking the rpms will drop down 300-700rpms and the lights will dim and then the rpms surge back up to normal. It does this at different speeds and gears, and is not the trans downshifting. There's no check engine light and other then that everything feels normal. Thanks!

[Scottydoggs]

volts drop when the idle drops. my car does it at night, fan power drops lights dim some. and my alt is rather new too. and i show 13.9 volts most of the time running.

so kinda normal.

[SgtMarshal]

if you have a voltage gauge you can see how much power is being created. a normal system runs at like ~14 volts

[Josiahsgtp]

So you guys think it might be alternator related? That would cause the RPMs to suddenly drop and then return to normal?

[SgtMarshal]

honestly, as long as there is no driveability problems, I wouldn't worry about. my lights dim and rpms drop from time to time as well. I was just suggesting that if you have an aeroforce gauge you can set it to display voltage, and if it is consistently low, maybe you have a problem more serious than we think. I would imagine that is unlikely based on the symptoms you describe.

[Josiahsgtp]

I have an palm pilot and the LS1m program i just havnt gotten around to setting it up. Ill try and take a look at that when i get a chance. Thank you!

[Scottydoggs]

So you guys think it might be alternator related? That would cause the RPMs to suddenly drop and then return to normal?

its normal, i got a new alt and it does it. the old one did it too.

[nik12937]

Maybe try cleaning your grounds in the engine bay. I haven't had this issue since redoing all the charging system wiring in my engine bay, so it could be related to clean connections and/or wire gauge. I used 1/0 gauge but it's overkill if you aren't running a H/O alternator and two batteries like my current setup, even 4 gauge is a step up.