2008 Tundra 5.7 Low Idle

Hi everyone,

I have a 2008 Tundra 5.7L that recently had a new starter & alternator installed. After I got it back I noticed that the RPM's were low (~500). The voltage is also sitting around 12.6 when running which is low. I disconnected the battery and there’s no change in the rpm or voltage. I also tested the battery which came back good.

Has anyone had similar issue and/or know what could be wrong?

Thanks!

 

Not with a Tundra but my 08 Explorer. Went through 3 "new" alternators before getting a good one. Each replacement before the good one was less than 13v output. If that's the case, don't run on it long. It'll kill your battery pretty fast.

 

It’s funny you just posted this. I was experiencing the same thing and put in a can of Royal Purple Max Clean fuel system cleaner and my idle started increasing after I used about 3/4 of the tank. I put in a little more than a can since it only treats 20 gallons. I put it in before I filled tank. I’ve used it a few times before with pretty good results. I use it on my lawn equipment too, even my 2-stroke stuff.

 

Mines seems to do this every time I disconnect the battery for maintenance or what not.

Drive it for 20 minutes, see if it clears up. Mine does after a little bit of drivin’ around.

 

Battery disconnect will cause a low idle until the ECM relearns. But that 12.6V while running doesn’t sound good. Is it any higher running at, say, 1,000 RPM?

 

Very common after disconnecting the battery. Should idle normally after driving it for a while. It also could be an indicator that you need new Spark Plugs. When I disconnected the battery a couple months ago it idled normally. I had replaced the plugs maybe 10k ago. When I did the same thing a few years ago, my truck had original plugs and idled like yours did for a few days.

I hope the alternator isn’t bad out of the box, because that isn’t exactly an easy replacement as you know. If the alternator is bad, I would spend the extra for an OEM Toyota one. FYI currently the OEM is NEW not rebuilt which is even better.