OK...so..not too long ago my 96 4runner started misfiring on cylinder 4. since the truck is like 15 years old i decided to change a few things :

spark plugs to platinum ones x6
spark plug wires x3
ignition coils x3


so misfiring went away for awhile..and then it comes back..same cylinder!...then its randomized...comes and goes...and its not at any particular time....RANDOM!...

im wondering if there could possibly be a leak or something in the cylinder...when i pulled the plug out and smelled it..it kinda smelled like antifreeze...that sweet smell. but dunno for sure.



any ideas on how to troubleshoot a misfire?..the chilton tells me how to find it..but not how to troubleshoot it.

 

Something I have experienced has been a broken connections on the coil.

You could try switching coils and see if the problem moves from cylinder to cylinder.

Also, to check an injector, place the tip of a screw driver on the injector of the cylinder that is missing, and then put your ear to the handle. You should hear it cycling. If not sure what its supposed to sound like, try out a couple different injectors to get a feeling...

Hope this helps

 

Two simple tests to see if you have a headgasket leak:

With the truck at operating temp, squeeze the top hose. If its hard, you have a leak.

Another is to remove the oil fill cap, and look for a chocolate milk substance.

 

thanks guys..let me try both of those real quick

 

i just had that same problem in my 96 taco. did all the same things you did, checked coils, changed wires, changed plugs... ended up being the injector. now i dont know if mines was just bad or if it was clogged but i ended up getting a new beck arnley injector and PROBLEM SOLVED! you also want to change all the o-rings of the injectors on that side rail. i didnt and ended up with a small gas leak because of it. ripped the plenum and stuff off all over again because of one little oversight.

 

im beginning to think its an injector also...other than being random...its really bad once i get above 70mph...i think the injector cant keep up. i replaced all coils wires and almost changed the ignition module but didnt cuz it seems to be working.


DOES AUTOZONE CHECK INJECTORS LIKE THEY CHECK ALTERNATORS?...i wouldnt think so but thought id ask. maybe i can just shoot some gas thru it to see if it sprays good. i dunno.

 

So I did this entire charade. To trouble shoot pull the bad injector from cylinder 4 and swap with any other cylinder and see if the trouble code follows the injector to the new cylinder. If so BINGO, replace injector and O rings.

Your injector should smell like gas.

 

YEP...seemed to solve the issue.. thing is...i totally tried to do it without switching the 0 rings....and.. GUESS WHAT....fuel leak... so took it all off again and replaced the o rings.. what sucks..is they come in a pack of 4 not 6 lol..