09 tacoma 2.7 starts, dies

I was thinkin to keep it from running it would be hearable at least. It dies like u shut key off with maf plugged in but unplugged idles at bout 700 after warm.

 

At 3000 rpm steady vac reads a steady 15

 

Im stumped? I guess we will have to take it to stealer? Ive dun everything i can think of? When it dies it will instantly start back up with no hesitation at all? No long crank no stumble? Just like i shut key off then right away restart?

 

Did you check circuit integrity between the MAF and PCM?

 

Just throwing out some ideas at the dartboard:

Do you have an aftermarket or OEM security system? Has there ever been one installed?

Can it be something in the ignition switch where contact is made and then broken due to a loose/broken connection? After starting try holding key in different positions while in ignition position. i.e.: slight pressure away from you, slight pressure toward you.

Start looking at the wiring as Dm93 suggested and also look at the wiring harness behind the engine and under the air connector. Maybe a critter chewed something?

Maybe you are loosing voltage due to a broken/weak connection in positive or ground circuit. Put a meter on a constant hot circuit and a local ground and see what it does after engine start. Maybe use one of the towing fuse locations (3 or 7, I think).

 

Ok, i visually looked at wires and harnesses as far as pulling wires out of loom and checking it inch by inch, i did not use a meter or anything as i dont know pins or anyghing like that? I unplugged ecm and replugged, i did that with all connections and sensors. I will check voltage and see but its almost like ecm is bad? Im stumped. Itl run fine with maf unhooked.

 

I'll grab diagrams and pinouts for you later, I'm at work right now.

 

I should have read the thread more closely. Didn't realize this.

 

Id really appreciate that! Thank u

 

Pin 1 (Blue/White) of the MAF sensor should have battery voltage with the key on.

Also need to check circuit integrity between Pin 2 (Red/White) at the MAF and Connector E5 Pin 30 (Red/White) and Pin 3 (Red/Yellow) at the MAF and Connector E5 Pin 28 (Red/Yellow) at the PCM, also with the PCM and MAF unplugged check them for a short to ground.

 

That fact that it runs without the maf makes me think the ecu is getting conflicting data from maf and tp (throttle position). Unplug the maf and the conflict goes away, but bad tp data only allows running at certain rpms. Just a guess but use scanner to observe tp data for accurate relflection of throttle position. How is an issue like this not throwing a bunch of codes? I haven’t seen any posted here and could be clues.

 

Well no voltage on pin 1 at maf blue/white?

 

Well that would definitely do it, I'll have to look at diagrams but I'm pretty sure it's powered by the EFI no 2 fuse.

 

I maybe didnt havd good connection 1st time? But i have bat voltage now at blu/wht and still same prob. Wires are good from comp to maf? Could ecu be bad?

 

Im stumped? I guess it could be the ecm?

 

I guess it's possible but they don't fail very often, doesn't make sense that it runs with the MAF unplugged but not with it plugged in.

Did you load test the Blue/White wire with a test light?
What are your MAF readings with the new sensor?

 

Ya it has batt voltage at blue/wht wire at maf. And readings on maf do exactly same as with old maf, absolutely nothing changed with new maf

 

Same as old sensor nothing changed

 

But did you load it with a test light?
https://youtu.be/xazvmJ8_p5Q