DO NOT accidentally turn on you truck without the air intake and MAF sensor connected

Accidentally did this. Was the most minor-heart attack moment I've had in a long while. I felt so bad for my engine and truck for doing so. It felt like if I would have kicked an old dog of mines or something similar.

Turned on the truck and it ran for like 2 seconds before it let out a nasty sounding whimper and shutting down. Connected everything back, and now runs as fine as it did before. I would not recommend doing this.

 

Not going to hurt anything as long as no dirt or debris gets sucked in.
The engine will not run very well if at all with the hose disconnected because the MAF sensor in the airbox lid tells the PCM how much air is entering the engine so it can deliver the appropriate amount of fuel, if it sees no reading from the MAF it's going to cut all the fuel. If you keep trying it will eventually flag a trouble code for the MAF and substitute a default value for it to allow the engine to run as a "limp home" strategy.

 

It will shut down from lack of a MAF signal

 

Do this in a turbo Audi and watch the cluster light up.

 

As far as I know, it should start and run fine, just in open loop. This can be a useful way to diagnose a faulty MAF: if the engine runs better with the MAF unplugged, then the MAF may need replacement.

Disclaimer: I have left the MAF unplugged on OBDII cars in the past without realizing until the CEL lit up. Haven't tried on the Tacoma.

For your viewing pleasure:

 

Yep, it's a factory-installed "feature".

 

Interesting all 3 of my3.4 Engines will shut off with the MAF disconnected

 

Kind of like how these trucks come with rusted frames straight from factory.

 

I don't see how this would be a bad thing other than if you sucked in a bunch of dirt without the air filter in there.

No worse than stalling the engine, thats basically all that happened

 

It will not shut down, it will go into limp mode and run rich.

 

No need to argue the engines all shut off.

Will not even start with the MAF disconnected does this mean all three are bad?

With them plugged in no lights

Maybe I wired something wrong in all the Engine swaps.

Since all three pretty much came in a box

 

I'm not arguing. I just know that I unplugged the MAF on my 96 to solve an idle issue to get me to work.

 

Agreed. Just felt a nasty feeling doing that to the old engine