hi all, i'm new here. this is my first post and hope someone out there can help me. i have a 1996 4runner, 3.4l v6, 170K miles.i just recently recieved a code 0304, cylinder 4 misfire detected. now i replaced all spark plugs, plug wires (all 3 of them), and i even changed the coil pack that controls cylinder 4. with all that being said, still have the same problem . any ideas what's wrong? what else could be causing this nightmare. my runner runs like garbage .

 

P0304 Cylinder 4 Misfire Detected

Open or short in engine wire
Connector connection
Vacuum hose connection
Ignition system
Injector
Fuel pressure
EGR system
Manifold abosolute pressure sensor
Mass air flow meter
Engine coolant temp. sensor
Compression pressure
Valve clearance
Valve timing
ECM

 

Thanks for the suggestions.
Well, I've come to the conclusion that i have probably got a burnt valve in cylinder 4. OUCH! Now I've been calling around, and it seems that most mechanics do not want to work on 4Runners at all. I just can't see myself spending a couple of arms and and a pair of legs to let the dealer work on it. Anybody out there have a shop manual on how to remove the cylinder heads? Any help would be appreciated.

 

Local libraries have books, if all else fails.

 

never thought of the library, thanks. i'll have try that.

 

well to update, i did a compression test and i had compression between 150-180. i put everything back together and now i have misfire i #2 & #4 now. i have just changed the fuel filter and pcv valve, as well as pulled the fuel injectors. i will be sending them out tomorrow. i will also be changing the o2 sensor. i will update once i get the injectors back. any more suggestion will be appreciated.

 

well i just got word back from Accurate Injector Service (http://www.accurateis.com) that i have 2 fualty injectors. so i got the 4 injectors serviced and bought 2 injectors from them. s othey are on their way back, i will keep you guys informed.

 

Also check all your grounds. I would recheck the plugs also, I had the misfire code and it ended up being a cracked plug, even though it was a new NGK.

 

i already did all that. that's why i went to the fuel injectors. i did everything via the process of elimination. i'm starting to understand why mechanics don't like working on 4runner 3.4s. it's a real pain.

 

well good news folks, i fixed it. turned out it was indeed the fuel injectors. got it all back together and she runs good. i also threw in a timing belt and water pump change, fuel filter, o2 sensor, pcv, and even a coolant flush. definatly not a fun job, but i learned a lot.

 

Nice work. If you plan to be your own mechanic, maybe you could pick up the factory service manuals from your local Toyota dealer... They're not cheap, but they'll pay for themselves, and nothing is left out.

 

This is a very helpful start for my own problem. New subscriber, I understand that I cannot post my own threads yet.

Have a 2001 Toyota 4Runner 3.4 Stock, 135,000 miles.
Engine Degrease and Power Wash, following instructions ran for 15 minutes, at the end of the engine dryout period, engine began to misfire.

Check Engine Light, P0306 Cylinder 6 Misfire.
Reset, misfire continued. Took to mechanic.
Diagnosed Cylinder 6 error codes, recommended coil and plug replacement, with no promises of resolution.

I replaced coil with Denso First Time Fit and DENSO 4501 Plug.
No resolution of this problem. P306.

Tried placing old coil in Number 2 position. No change to error codes.
P0306.

Next Steps or source of repair manuals advice?

 

Factory Service Manual: http://www.ncttora.com/fsm/1996/SIL/fsm/repair.html

Misfires:http://www.ncttora.com/fsm/1996/SIL/...e/cip0300p.pdf

I'm guessing injectors but follow the manual.

 

Thanks for the link to the Service Manual. Found water contaminating fuel. Purged. Resolved. Thanks Again.