05 toyota tacoma wont stay running.

Hi there I have recently posted on thread but wanted to follow up an try again. I have a 05 toyota Tacoma 4.0, about 3 weeks ago, my truck seemed like it was lunging me an almost didn't make it home. I went though threads an tried to troubleshoot it myself. Here is what all I have done.

Mass air flow sensor (New)
Air filter(new)
Spark plugs (new)
Downstream left 02 (new)
Pcv valve (new)
Sea foam fuel system( then replaced fuel pump system)
Sprayed brake cleaner on all vacume hoses and around manifold to see if idle returned to normal, (didn't help)

It would run then rough idle, press the gas an would stay running. Took it to get diagnostics test an Would not stay running long enough to test any one thing in particular.

Did not through any codes..

Now when you start it, it will run for a second an die

 

Maybe a vacuum leak

 

Fuel pump?

 

Have you disconected the battery recently?

 

Yeah...disconnected the battery

 

How are the battery connections? How old is the battery?

 

Changed the fuel pump

 

Almost new battery.

 

Do you have a scangauge 2, Ultragauge, or know someone close enough that has one to check your engine voltage? A voltmeter perhaps?

 

When you said it would run with the foot on the pedal, at higher rpm than idle, how did it sound? Normal, or rough running?

 

2ND took it to a snap on guy to try to test/read codes.
NO codes an wouldn't stay running to test things out?

 

Rough, that's when we checked the vacume hoses

 

Continually rough then. May be a coil pack issue. May be the alternator. May be neither.

If you can check the voltage while running, that would be very helpful.

Also, while you have the engine running, try to keep the revs to ~1000 (since it dies with your foot off), unplug the wires from each coil pack one at a time. Wait long enough to see if the engine operation gets rougher, or stays the same.

If the operation gets worse, that coil pack is working properly. If it doesn't change, then that coil pack is a possible culprit.

 

What all electrical mods does your truck have?

 

possible TPS is bad?

 

Stock truck. No changes. Can't keep it running to check coil. Tried to put the foot on the pedal, but dies. We are taking it to the dealership tomorrow. Just wanted to try an save some $$$. Simple 150 just to have them try to diagnose it.

 

Anyway I can test the tps?

 

Keep us posted. Very curious what you find.

 

Yes. Remove the intake from the throttle body. Turn the key to the ON position. Have some one watch the throttle valve while another pushes the pedal. See if it moves.

 

When i disconnected my battery my truck did the same thing. Ran rough and acted super funny. Im pretty sure if you disconnect it it messes with the memory of the computer and has to relearn by going through a drive cycle? I Could be wrong