Misfire Cylinder 3 Running Rough

I am getting a misfire on cylinder 3 code along with a check engine light on my 97 t100 with the 3.4 engine. The spark plugs are fairly new, I replaced the coils and wires since the problem started. Last week I replaced the cylinder 3 spark plug and the engine ran good for about 100 miles and the check engine light went off. The light is back on and the truck is back to sometimes running smooth sometimes choppy. Bad Fuel Injector??

 

check the injector....

 

What kind of plugs?

 

i wold drive to much while its running like that. its a good way to trash a piston. best bet is to read the plugs if your running lean if could be a fouled injector. i had the same issue. if its not the injector try a new plug. you might have gotten a bad plug. if not that you can do a compression test.

 

I did a compression test today and 4 of the cylinders where about 180 psi and 2 where at 190. Those seem like good numbers considering 180k miles on the motor. I did install Bosch plat. 2 spark plugs which I later discovered are frowned upon, but could they cause the truck to run this poorly? I guess the next thing to check is the injectors.

 

Your comp. numbers are fine, you said it threw a code (engine light) What was it? if diagnosed, Bosch's are good plugs just not for Toyotas I guess (split fire for 3.4) Not sure its an injector, maybe faulty coil pack ? You replaced wires too huh... Hmm , ran good for a 100 miles then back to shit

Could be alot of things next time it throws code you need to go to AAMCO or some other freebie place that will put it on a code reader..

 

i forgot about them lol definatly replace wires and coil packs....compression sounds ok....was your check engine light flashing? still sounds like a injector to me

 

x2 and then HAVE to have dual grounds....

 

I still haven't found the problem but I did get a P0441 code (Evap Emission Control System Purge Flow Fault) instead of a missfire code but then I cleared it and it went back to a missfire code (my mistake above, the missfire has been on cylinder 2 all along). I've read a post on the P0441 code and it coulld be many things that I will start to check out.

 

A P0441is usally the evap canister and possibly the duty valve aswell if it doesn't come on the canister. (Some do some don't with toyota). Do you have spark on that cyl? Also did you check the plug gaps before your install?

 

I've tried different plugs on that cylinder and still got the missfire, and yes I have spark on the cylinder. Is there any way to check if it is the evap canister or duty valve before I replace more stuff that doesn't need replacing?

 

If you're sure spark is present then, IMHO the evap code might be just coincidence and has nothing to do with the misfire. Might want to send atleast the one injector to be flow checked, cleaned and recalibrated. All of the injectors if you can swing it.

 

if you have spark, you're either missing air or fuel. Try the injector, that's probably it.

 

Or for a quick free test, you could swap the injector to another cylinder and see if the misfire moves with it. If it does, there's you "smoking gun"

 

mark and swap injectors, spark plugs, and coil packs.

 

win 1

win2

win3

win4


thats 4 free things to try to help find the problem....damn what would the world be like with out TW

 

NOt sure what "tighten the fuel cap again" means, I tighten it till it clicks always, can you clearify?

 

I've swapped the plugs and coil packs with no difference with the code, I will swap the injectors next.