Stumble and almost stalls on start up (1 Viewer)

[skmaynard1]

Hey guys,

So my 2013 has all of the sudden started to stumble just after start up and feels like it’s going to die with a low idle. It only happens at start up and quickly goes away. Additionally it happens frequently regardless if the motor is cold or warmed up. This has been going on for a few days, and is progressively getting worse and more consistent.

Coincidentally, I also noticed this week that my heat only blows hot when the car is moving. While sitting still it blows cold. Not sure if this is related as it seems like possible low coolant. I idea how long this has been going on, as I never use the heat in Florida. I only think to check it after I’ve been driving and it’s hot, so I haven’t had a chance to see how the coolant looks.

YPDATE: just noticed while driving that my temp gauge is all over the place. Creeps up, then drops back down quickly. Possible thermostat issue? Does this while driving not stopping.

I haven’t had time to look into anything yet, but plan to dig into it sometime this week.

Any thoughts?

 

[bloc]

Search in this section for fuel pump ecu. Also possible it’s a fuel pump.. teckis300 has a good thread about similar behavior near idle when the ecu turns down voltage to control fuel pressure.

Also yes, check coolant level ASAP.

 

[isthatalexus]

It's a Land Cruiser, so a simple first step is to test what kind of voltage the battery is holding. This is the biggest LC/MUD cliche, but for a reason. Being a voltage snob is just part of being a member of a regal vehicular lineage.

 

[skmaynard1]

UPDATE AND QUESTION:

So I had a chance to look into the coolant, and it was low about 1 gallon. I filled it up and it seems to have cleared up all issues. Which leads me to some questions.

1) Does the 200 have a heater control valve that stops fluid from flowing through the heater core when the heat is not in use? I ask because this is the first time I have used the heat since my radiator was replaced a year or so ago. Is it possible that it was not properly filled and the heater core was empty that entire time? Then, when I used my heat last week it opened up and lowered my coolant level by about a gallon?

2) How do I check for a valley leak without taking too much stuff off? I have not seen any coolant on the ground, no smell of burning coolant from an external leak, no smoke from the exhaust to indicate head gasket leak.

3) Is there any chance that low coolant would cause the stall situation on start up? I can't imagen how this is possible aside from potential coolant in the cylinder. However, I would think this would produce smoke and would only happen when the vehicle has been sitting long enough to accumulate it. The issue did happen after short stops with the engine plenty warmed up as well as overnight cold.

For now my problem is fixed, but I would like to have a better idea of what caused it and if I need to do any additional testing.

 

[04UZJ100]

Low coolant should not affect engine stability on startup.

 

[bloc]

Unless the coolant was low enough that the coolant temp sensor was uncovered and giving the ecu an inaccurate block temp reading.

Getting under the truck and looking for lines of dried coolant on the bellhousing is probably the easiest method.

I don’t think there is a coolant control valve for the heater core but am not totally sure. If so it’s behind the dash, and Toyota generally tries to avoid dynamic seals on the cooling system within the cabin because of the likelihood of leaks. More likely it just controls airflow through the core, but again, I’m not certain.

 

[isthatalexus]

Here's a good place to enter the valley coolant leak rabbit hole: Kind of "Mystery" Coolant leak back of engine (heat exchanger valley leak) - https://forum.ih8mud.com/threads/kind-of-mystery-coolant-leak-back-of-engine-heat-exchanger-valley-leak.1004327/