1st gen tacoma

Curious of any direction to turn to. i have a 2001 Tacoma 3.4 L 4x4 manual . i have had a check Eng light on for some time. a week back it started running rough , replaced all 6 plugs , it still ran rough. finely had a friend code it . Got a single P0303 . miss fire on #3 . replaced the #3 coil , it still ran rough. then after re fueling it hardly ran then died. i was able to restart and get back home. replaced #3 with a new injector . now after coding again , getting codes of P0301 / 302 / 1135 . so miss fires on 1 & 2 and now an O2 sensor. iv'e never had a issue with this motor until now , all parts are orgional.

 

Do a compression test, see what kind of #'s you get.

 

Also, your sure you have spark on that cylinder?

 

could be the upstream O2 sensor as well, when mine went bad I had a similar experience.

 

I'll have to get my hand on a tester . i hate to consider a possible burnt valve, thanks for the info.

 

At first it was #3 , then i pulled the coil and it was firing / good spark. still i replaced to coil. iv'e also replaced the injector for #3. Now i am getting miss fires on No #1 & 2 , a code for an O2 sensor now that did not show when we first ran a code test. so ill look at the O2 sensor next. thanks again.

 

Yeah if your downstream cord is long enough you can just try swapping it with the upstream to see what happens so you don't waste cash. In my case I had to take the plunge and buy a new one. Picked up the denso off of Amazon for $45 and it cleared my codes and took care of the rough idle.