Thing bucks and misfires. Any ideas right off the bat?

No codes.

1996 4Runner
V6 3.4
Manual 5 speed 4wd
Supercharged

My ideas.
Bad plugs...
Bad fuel pump...
Bad injector...

Thanks for any input.

Happy Monday.

-Joe

 

no codes, you hooked up a scanner and downloaded blanks ?

if it is misfiring it must have a code and will have a code.

anyhow, check all the above you posted

 

Another good one is to check is the mass air flow sensor. normally it throws a code when it goes out but it would be good to check just in case. If part the rheostat inside is worn out it won't tell the computer how much air the engine is getting causing the mis-fire/bucking.

 

Did it just start misfiring? It may take a few drive cycles before it flahes a code. Make sure all intake hoses, clamps, etc are attached and tight. Spray water mist on plugs and plug wires to see if the misfire worsens. A couple of thoughts...

 

When mine did this, it was the injector.
Get someone to do a compression test on all the cylinders, Turn the engine over, and when you release the pressure from the cylinder...Smell the air that comes out, if you dont smell gas...Most likely an injector on that cylinder.
There's probably an easier way to tell, but thats my shade tree mechanic way

 

I'll add to this mess. I got the car about almost 2 years ago. Before I got it in my hands the owner / family friend had it fixed cylinder #4s exhaust valve took a dump on it.


I've put 10 thousand miles on it since the heads have been done and I swear the head gaskets are leaking. My coolant isn't oily or my oil like a milkshake. But it does overheat if the heater loop isn't open. Yes this is 2 different problems in one thread i'm aware.

Thanks for any input guys.

Oh and this awesome exhaust leak from the y pipe header is still going on because the y pipe from trd no longer exists.

 

Toyota V6 - known for head gasket leaks. Coolant can leak into compression chamber and not affect oil & visversa. You need a "cylinder leak down" test to see if there is a head gasket problem, valve problem, ring problem. A vehicle can have compression but still have problems.
LEAK DOWN TEST -
Cylinder on compression stroke - both valves closed piston at top dead center TDC
pressurize cylinder - two gauge tester
determine % pressure loss
listen for air loss in ehaust system and/or intake system and/or crankcase and/or cooling system.
Repeat test on all 6 cylinders
remember the engine must be rotated to TDC with both valves closed.
A shop with a scope can see if or what cylinder may have an ignitin problem or injector problem for the misfire.
Not the best to do but pullingthe plug wire off while running or disabling teh injector for each cylinder while running can identify the problem cylinder.
Exhaust leaks are more problematic than just noisy, they CAN affect engine purformance, but this is probably not the case with your vehicle.
Gary ASE certified Master Tech, also certifiable good luck!

 

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....Yeah...What he said