Hi all,
My 2001 Ford F-150 Lariat, 4.6 engine is having some trouble. When I am in Park, or at a red light the truck sometimes does something funky. The engine temperate reading sometimes becomes erratic or drops to C. When that happens, the truck begins to rev up and down a bit. Once it even shut off, and for the first time this morning I briefly saw a red oil light come on. I was at a stop, so when I pulled forward to park it went away. This never happens while I'm moving, only at a stop. It's been going on for a long time.

Here's video of what typically happens. This time it didn't drop all the way to cold, but a lot of the time it does.

Maybe just a bad coolant sensor? I was confused on what and where this truck has for that. I think it's hiding behind the alternator but I'm not totally sure.

Ryan

 

Knee jerk reaction is, I'd be looking for a ground issue.

 

Yeah, definitely sounds like an electrical issue, with it being erratic, and when you are coming to a stop maybe something is grounding/shorting out causing the issues with the gauge readings.

 

Have you alternator checked also.

 

Thanks guys, both are great thoughts. I didn't think about the alternator at all and I've never replaced it. Not sure if the previous owner ever has. Maybe that would explain why it never happens when the car has a RPM that is higher than idle, but at idle it starts to not get enough voltage. I replaced the battery last year because it had died on me, it was due. I haven't had any problems ever since though with it so I figured the alternator was fine. Maybe good enough to charge but not enough to supply enough power?

As far as grounding... I have no idea of where to even look for that.

 

There are grounds on the firewall by the solenoid, on the frame near the starter, on the inner fender near the fuse box, There are 2 behind the drivers side kick panel, And 1 or 2 behind the passenger side kick panel.