switched the coils.......cylinder misfired today i went to autozone to read the code and the 5th is still misfiring so that means coil is fine, has a new spark plug, wires dont matter because it is on the coil side. could it possibly be a bad injector? i need to check the timing belt as well, but i dont have too much time right now. i guess the only other possibilty is doing a compression test to see if all the valves are ok

 

How many miles did you say were on it??? original wires??

 

I had the same problem after I did my plugs. the gap was incorrect too narrow i believe and i got a ocasional misfire and a check eng light. I regapped and all has been great.

 

it has 150,000 and it cannot be the wires because it is on the side of the coil pack and the coil is fine..the plug is brand new (the second one) and it gapped fine

 

Are you 100% sure your above statement is true? Yes #5 has a coil above it, but are you sure that the performance of the coil over the #5 cylinder is unrelated to the condition of the wire going to cylinder #2...

If this system is similar to the waste spark systems I have dealt with in the past, the coil fires and sends spark to 2 cylinders at one time, in this case cylinders 5 and 2.... #5 cylinder is under compression and takes a lot of voltage to fire, and #2 is not on compression so it takes next to zero voltage to fire. The coil can easily output enough voltage to take care of that. But if you were to take the wire going to #2 and give it REALLY high resistance, higher than the resistance caused by the compression in cylinder #5, then LOTS of that coils output would be used up trying to get cylinder #2 to fire, not leaving enough available voltage to fire cylinder #5.... ECU sees a missfire, CEL light comes on, you post here for help....

Will the wire from cylinder 3 to cylinder 6 be long enough to swap with 5 and 2??? if so for the 2 minuts it takes swap the wires it may be worth it....

PS. Still convinced it cany be a wire?

Cheers
Bob

 

so if it is using more voltage for cylinder 2 due to higher compression then the 5th cylinder is not holding compression (possible messed up valve) or the timing could be off

i really dont understand why the wire could cause the problem. the coil causes that cylinder to fire the wire just runs to the opposite side i dont understand why it would mess that one up but i will still switch around the wires.....it would be easy to catch the problem if it happened all the time so it may take a week or so for me to know if the problem followed the wire or not

ps. if any or this sounds like a 2 year old wrote it sorry its like 4 in the morning haha ill re-read it tomorrow and maybe understand it more

 

Bob, I am not sure what you are saying makes sense because electricity will always follow the path of least resistance so if you fire both plugs at once which simultaneous (waste spark) ignitions do then the the #2 plug might just not fire (due to the resistance causing a voltage drop) and send all the juice to #5 to fire that plug. If your logic is correct then you also should see a misfire on #2. It is common to have a double misfire when a coil goes bad for exactly that reason. Maybe I am incorrect on this, but it doesn't follow logic as far as I can see.

How many new plugs have you put in that cylinder?
....I still think it may be the plug causing the issue.

 

i have relplaced the plug twice now....today i will switch around plugs and plug wires just to see if the problem follows

 

do you think that it could possibly be a bad injector? i ran injector cleaner though it when i first bought it back in oct. but could something be clogging up the injector?

could it have been the injector cleaner that messed up the injector (it was the lucas injector cleaner i have used it in both of my trucks and it has always been fine before)

its a long shot but i am getting desperate here

 

MTL 4runner... Its been a long time since I went over the basics of waste spark... I may be out to lunch here too... but switching a wire is free.... Its another good little test

As I said though... I believe that the basics of it are that when the coil fires, it fires both spark plugs... the coil has a max voltage it can produce. Since the #2 cylinder in this case it at TDC exhaust, the comperssion in that cylinder is zero, thus very little resistance to fire the plug.... but if you go and add resistance to the plug wire, then you will require the coil to work harder, and if you dont leave it enough available voltage to fire #5 properly then you will end up with a missfire...

Also too, im not sure about the Toy system, but some of the older OBDII systems had a little bit of trouble picking the cylinder ( between the 2 on the coil ) that was missing in a waste spark system. The ECU looks for a variance in crank RPM to determin which cylinder is missing, but it is not always 100% accurate.

By the way xxxrider, if the code comes back with a cylinder 3 missfire, then I want to see your sig say "or dirving a chevy"

 

dude that is way over my head i have never herd of that....but at the same time i never herd or coil packs before i had my yota but i am going to switch the wires around as long as i can i dunno if they are different lenghts...maybe i will just go buy new ones depending on the price

 

I deal with this all day long

Its hard to diagnose over the internet, but I can offer up as much help as I can.... Im not saying Im right with my diagnosis, but if you can switch a 2 SP wires and confirm that its not one more thing then it was worth it!!

 

of for sure you have to make sure that you check all of the simple things first....man i just want to figure this out so i can start the caging

 

you guys all suck. when my truck starts to act funny i would kill to plug it in to a little box and have it tell me whats wrong. i have to sit there and scratch my head and start taking stuff apart! good luck tho, that misfire is quite annoying i may add.

 

Oh come on darth brian... when yours doesn't run right you adjust the carb and change the plugs

 

You forgot to mention adjust the point gap!

I do agree with Bob to try switching the wires since it is easy to rule out as a possibility.

 

That dang point gap... gets me every time!!!

 

the plug wires will be switched once the rain is gone (no room to work in garage) and i come home from work at a decent time

my test right now is i have the plugs switched around and seeing if it follows the plug and if the 5th still misfires then i will switch the wires...you gotta do one test at a time or else you could end up replacing the wrong thing ya know

 

Any updates??

 

its still chugging along no misfire no check engine light so far but like i said it usually takes at least a week so i am kind of hoping for a misfire so i can do the next test