Rough Idol on 99 Tacoma

I have a Automatic 1999 Toyota Tacoma Pre-runner with a 3.4L V6 with around 180K miles. This truck has been very well taken care of, and has never given me any problems until this morning. It began to idol really rough, and seemed as though a piston wasn't hitting or something. It seemed to be triggered when I cut the A/C on, but even after I cut it off, the rough idol still persisted. I've owned this truck for 2 years now, and I've never had ANY issues at all until this morning. I've done quiet a bit of maintence on it in the past 12 months including : K&N intake, NGK Plugs/Wires, changed fuel filter, oil/oil filter, tranny flush, and ran seafoam through the engine. Any help would be greatly appreciated.

 

If its just the idle, I would investigate the IACV first. Its loated on the Thottle Body and its not that hard to take off, take apart and inspect/clean (search around there are a few tutorials)-- but before doing that, ensure to have a new/fresh Toyota IACV gasket on hand for when you put it back together.

I started to have a rough idle/stall out at stops. I suspected (and still kind of do) the torque convertor lockup staying locked up when coming to a stop, but after taking my IACV off and cleaning it with brake cleaner, the problem has gone away (odd because the IACV valve moved freely during my inspection- I suppose even the slightest build-up or tiny sand granule sized obstruction can affect the closed loop PWM system from performing properly).

 

Could be a lot of things.. It really might help narrow some things down if you could get a code on it. Since you've fairly recently changed plug wires etc. Go back thru and check connections there. It could even be you Catalytic converter about to die on you. Good luck.

 

One thing I haven't been liking with my truck is how darn stubborn the ECU is at throwing codes. I bet some guys like that that little light doesn't come on easily, but I have a car that throws a code for any little thing and its a blessing. Just throw a scanner on and bam, leads you to a small problem before it becomes a big problem. I was pretty pissed that my truck could run so badly that it even stalled out, but wouldn't throw a DTC to point me in a direction. Sensitive OBDII has spoiled me haha.

 

So after 2 long nights of working on the Taco I found the issue. My cylinder 1 fuel injector was bad. I ran a code reader on it, and it said misfire on cylinder 1. So then I changed the fuel injector to cylinder 3, reset the code then I hooked it up again. The new code said cylinder misfire #3. Tried to clean out the injector, but it only ran fine for a few hours then back to rough idle. So I went out to autozone and bought a new injector for about $100, and it's been running great since. Thanks for the advice everyone!

 

Good deal.. Getting a code is so much easier than continual trouble shooting.
Makes me wonder sometimes when you think you're doing good by trying to take care of a vehicle by doing some of the things you mentioned in your first post, one of them could have caused that to happen. Like maybe the sea foam loosened something up and at some point it migrated to your injector causing it to go bad. Just a guess, who knows.

 

So I lied. After replacing the injector on cylinder 1, the truck has been running PERFECT for the last few weeks, and then all of a sudden it started acting up again. Now it seems like there are is multiple cylinders misfiring. It actually died at a stoplight, which has never happened. It is also ironic that it was extremely hot today when it started acting up. Any suggestions?

 

Replace the other injectors that are throwing the codes...

 

at 190,000 i was having idle issues... spent a lot of money and time replacing the IAC valve, then fuel pump, fuel filter... was about to replace injectors, when someone mentioned to me to clean the MAF sensor since i have a K&N intake...

turned out the sensor was pretty junked up... now i clean it twice a year and have not had any problems...

my truck now has 301,000 miles and still going strong...

EDIT...

and yes, the truck even conked out on me on the freeway during rush hour traffic... annoying...