Weird stalling issue: Hitting bumps BUT only when cold

I live here in Colorado and believe I have an electronics gremlin in my truck, somehow, somewhere, who knows. I have 2+ miles of very rutted out dirt roads that I have to travel to leave my home to get to the pavement, and if I simply start my truck and go....it will stall on some of these bumps. It's stalled once, or even 5-6 times until it gets to the pavement whereas it's then good to go. Never an issue. I can hit all of these bumps with the most intensity coming home when the truck is warm, never a stall. Never.

Today I warmed the truck up for 20 minutes prior to leaving, never stalled. I've also:

- jiggled wires in the engine bay while running, trying to re-create it. Didn't work
- Cleaned the MAF, ensured battery was tight and clean
- Tapped the Fuel delivery module thingy inside the frame while running, nothing
- Jiggled wires under the dash, nothing
- Checked the ground cables inside the engine bay and behind the kick panels, nothing

What's weird to me is that it ONLY does it from a cold start. If I run it, it's good. If the truck is warm and I hit bumps, it's good. Driving on pavement anywhere, it's good.

Otherwise if I start it up and go for it, I get about 1/2 mile in and hit a major rut....check engine light on, battery light, dead. Put it in park and fires back up.

Maybe I have to take it to Toyota....

Truck has 185k on it, never had this issue before.

 

Loose negative battery terminal will do it.

 

That's definitely a weird one for sure, any codes after getting the check engine light?

 

So I took it to a local shop about a month back, hooked it up, it's throwing Code P1604 (Startability Malfunction).

That's all I got

 

Terminals are so tight you couldn't squeeze a ___ hair in there. And it's only when the truck is cold, which is strange

 

That code is very vague at best. Here's a link that might help to send you in the right direction.

https://www.obdadvisor.com/codes/p1604-toyota/

 

What are we talking about here? A 5.7L? Flex fuel or no?

 

It’s a 5.7, not flex fuel (i think?)

you know I do wonder if it’s the battery with some weird parasitic draw or something. I have a WARN winch and two pro comp LEDs hooked into it….

 

Thank you for this!

 

I’d do a battery load test to begin with, and if it has removable caps I’d check the electrolyte level too.

 

So I took it to the dealership. No codes, nothing wrong with the truck…of course.
They then do a battery load test and tell me the battery I bought this summer is bad.

replace battery.

I guess I’m glad it wasn’t more but am annoyed as well. I still don’t know how this impacted the staling issue, voltage wise, but just wanted to follow up.

 

FWIW, could have simply been a bad battery but.....some batteries don't like an overdose of vibrations or jostling around.