3vz misfire

[Crinale]

ok guys, i tried to search, but you know how bad the search is on this site :P

So i've got almost my entire problem with my new 4runner fixed, all the hesitating is gone.. now ive got this misfire i cant figure out..

I pulled the spark plugs, and they are fairly recent NGK plugs (i didnt replace them). I also replaced the wires with NGK, and replaced the cap and rotor. A shop said my EGR had failed, so i pulled the (known working) EGR off my 91 and put it onto the 92.. I ran a can of Seafoam in the gas tank with about 3 gallons of gas, then filled up with mid-grade fuel with a bottle of Lucas fuel system cleaner.

The biggest issues are at 10-75% throttle and/or low speeds. if i can get it above about 3k rpm while floored the misfire completely disappears and the engine pulls. if i go back to partial throttle the misfire comes back.

So, im thinking i may go pull/replace all the spark plugs even though they are fairly decent, maybe one could be a bad part? :headscratch:

Any thoughts?

[L33T35T Tacoma]

Do a compression test

[Obi..]

More than you might want or need but here goes..

You did short out the advance when adjusting the timing right?

Before you spend time pulling plugs try this first..
Warm up the engine then turn it off..
Now, pop the plastic retainer clips that hold the plug wires onto the distributor cap loose but leave the wires connected.

Careful here I don't want to hear you got a free mohawk sparking yourself out..Take a test lead and with the engine running ground out each individual wire and listen to see if the rpm's change. If it does drop a little each time the wires are shorted they're good, if not it's a dead plug, wire, or tracked up inside the cap causing a low spark cylinder.

Also consider these..

Distributor off a tooth.

Partially/temporarily clogged injector. (Only clogs under pressure increase b/c something isn't fully blocking the screen.)

Clogged EGR lines, the one's that go under the intake plenum are known to collect moisture and rust inside. Run a small piano wire through to clean and check for clogs.

Leak at the rubber tube from the air cleaner pipe to the manifold.

Clogged air filter.

Clogged, or clogging fuel filter.

Faulty fuel pump or wiring at the tank.

Faulty injector with a light short.

Has the block had any hg work done and both heads and block were decked? You need to off-adjust the timing and idle screw for that specific build then. IE: Lil'Bro's 4Runner had block decked and bored over like 20 thousandths and would not idle or accelerate right on factory timing. I had to advance the timing a bit more and then back off on the idle to get it to work and smog clean. Leave the advance shorted and it should goto 2500rpm without any issues..then take off the short and go for a drive with it. Readjust and fine tune as needed.

Let me know if you need the pages from the FSM and I'll clip them in.