2003 Tacoma Shuddering and Dying

I have a 2003 Tacoma 4-door with a 3.4 and auto, 4x4 with about 160k. Last week I was driving home and it was wet out, truck starting running rough. RPM's would drop from about 2k to about 500 when driving and it would hesitate and sputter, but then keep going. I had about a half a tank of gas. Thought maybe I sucked some water up, but I made it home. No code was ever thrown.

Next day, tried driving it, but it would shudder alot and when coming to a stop sign or slowing down it would die. I can put it in park and start it right up again. If I left it in park it would just die.

I changed out the air filter, fuel filter and no change. I thought it might be the TPS, so I bought a whole new throttle body assembly with new throttle position sensor and the other sensor (it eludes me right now what it was). It ran bad, died, then ran fine for about five minutes. Tried driving to work and it shutters on the highway and dies when stopping at lights or stop signs.

I put a 1/2 tank of premium gas in before going to work, ~45 miles each way. So, 90 miles after putting the gas in I brought it to Toyota and almost didn't make it there. They checked it out the next morning and they said it runs like a top. I picked it up, it ran great for about 20 minutes. Next day runs horrible again. They put it on diagnostic and said air/fuel mixture is good and all sensors are reading correctly.

Last night I put 'water remover' in the tank and it didn't run better. Drove 45 minutes to work mostly highway. I was down to a 1/4 tank, so I put in HEET (another water remover) and 5 gallons of 93 octane at lunch time. Leaving work it died three times getting out of the parking lot of work. I made it home after 45 or so miles.

I changed the spark plugs and wires just now, drove around the block and seemed fine, but then died when I put it in reverse to park in front of the garage.

What am I missing?
Can there be more water in the tank? Too much water remover?
Is my fuel pump going bad?
PCV?
EGR?
Vacuum lines?

I can't figure it out. Toyota is no help.

 

This may not be of any help (Im a poor excuse for a mechanic) but have you tried injector cleaner?


Welcome to TW

 

Had similar issue caused on a Jeep. Ended up the computer had water in it and the drying and then sometimes wet weather would mess with it until it fully shorted out. Could be something similar with electronics???

 

I am far from an expert but check your vacuum lines. Spray em with some carb cleaner.

Heres some reading of people who had similar issues

 

I have fuel injector cleaner, but I was waiting to get a new tank of gas. Maybe I shouldn't wait.

Water in the computer would make sense because it happened when it was wet out. It should have dried out though over the past week. Is there a way to test the computer?

Any other ideas?

 

Sorry... I have reached the upper limits of my mechanical prowess with the injector cleaner idea...

 

not an expert by any means but -- idle air control, throttle positioning sensor? ever been replaced?

 

The throttle position sensor was changed with the throttle body last week. No change in idling or running.

 

@Empty_Lord

 

Your 2003 shouldn't have EGR.
PCV (and grommet) are cheap and at 160k you should just replace it anyway.

I'll keep thinking of other ideas, but at minimum, you can try disconnecting your battery for a few hours and then reconnect it. The ECU will then go through the "relearning" cycle.

Another thing to try IF YOU SET IT UP SAFELY is to jack up the rear of the truck (jackstands, jack under the axle for extra safety, wheel chocks in front/behind front wheels) and go from Park/Neutral into D/R with the wheels off the ground. Maybe something is up with your transmission/torque converter that is causing the RPMs to drop and then cause the engine to stall.

 

Maybe try a new knock sensor (I hear they can wear out) but just a guess. Good luck! Edit: fuel pump relay, too

 

I'm having this exact issue with my 1990 Chevy right now, changed the Idle Air Controller, which fixed nothing. Checked the injectors just as others have mentioned, to rule out a fuel supply issue - look inside of the throttle body, you should see fuel spraying in a circle, and bump the throttle, it should obviously spray harder, which will rule out a fuel pump issues, or fuel filter issues.

I'm still searching for what the hell is wrong with this Chevy, but hope this can at least rule out something wrong with a pump or filter.

 

Sounds a lot like you have a leaking fuel injector. But hard to really diag over video. Data logging it would tell you a lot more.

To check for a leaky injector you can pull the plenum off and put a borescope down the hole. They should look dry after an hour or so. If one looks wet that’s a possible culprit.

 

You can’t see fuel spray on these engines. Your old Chevy us throttle injection, these trucks are port injections. The injectors are by the intake valves

 

Another thing to try is when it’s running good pop the hood and spray the plug wires and coils with a spray bottle of water. If it acts up then it’s an issue with whatever caused it.

 

I had the exact same issue recently with the truck running rough and dying at stops. Check all your grounds in the engine bay and make sure you're getting good clean metal to metal contact. I ended up finding a loose ground on the firewall that connects to the engine that was loose. Tightened it up and all my issues went away.

 

Good thing to check. The ground on the intake manifold is a good one to have tons of ignition issues since it grounds the injectors and coils

 

Doh, sorry.

 

eh we all make mistakes! lol

 

check the grounds first. Like mentioned above the ECU grounds at the intake manifold by the "Diagnose" box. There should be a ground from the battery negative to the inner fender well, another on the P/S head to the fire wall and the main ground from the battery to the block just above the oil pan.