MaK92-4RnR

My Cousin's 97 4Runner is throwing p0306. I know this code can be a royal pain in the ass on these particular trucks. But before I pull apart the entire plenum to change a fuel injector, Just wanted to be sure I've covered everything?

Specs:

1997 4Runner SR5 4x4
automatic
3.4 v6
230k miles

what's been changed so far:

Fuel Filter
Spark Plugs
Coil packs were swapped ( still the originals )
MAF Sensor cleaned + new air filter

She reported that she was getting bad gas mileage ( maybe 180 miles per tank ) I swapped her plugs, she got the same mileage. She then added sea foam to the tank, and now is getting p0306 code. I quickly assumed it fouled a plug, I swapped the plugs for her, cleared the code and its still there. So far I've cleaned the MAF sensor, swapped coil packs, change the fuel filter, spark plugs twice, and its still there. Any ideas? I have a feeling its a bad fuel injector, but I'd rather not have to pull apart the entire plenum to replace a single fuel injector ( she's a college student and injectors are 120 a pop )

I'm almost certain its the fuel injector because when I swapped the fuel filter, it took the code almost 3-4 days to come back on. normally it just came back on whenever the ECU relearned itself.

Anyway, I'm gonna slap some new NGK wires on it, and see if that fixes it, if not. I guess ill be pulling apart the whole top to do the fuel injector.

Anyone have any suggestions?

Thanks,

tantacoma

You could confirm its the injector by swapping #6 with the adjacent one (say #4 ?). If you then get a P0304, then you know its the injector.

MaK92-4RnR

Lol. So you're wanting me to pull apart the entire plenum, swap injectors, and then put it all back together, start it and pull it all apart again?

tantacoma

Didn't say it was gonna be easy. Just a suggestion that addressed your concern about buying an expensive new injector, possibly unnecessarily.

You could also check the #6 injector with an automotive 'stethoscope' to see if its making the normal clicking sound.

SacRunner

No advice on the P0306, but I can say, that during the course of my 3.4 swap I pulled the plenums enough times that I could get down to the fuel rail in about 20 minutes or so.

Basically, remove the rubber intake hose going to the throttle body (the main one coming from the air box). Leave the throttle body mounted to the upper plenum but disconnect the throttle cables, and unbolt the upper plenum from the lower and tilt the whole thing towards the passenger side, sort of pivoting around the throttle body (there are a couple coolant lines and a couple vacuum lines that can be left connected and should have enough slack to move out of the way; the vacuum lines at the rear of the upper plenum will need to be disconnected though). From there remove the lower plenum and there will be the 4 bolts holding the fuel rail to the intake manifold. Going this route you're only replacing the 2 plenum gaskets, which are the same.

It seems involved looking at it, but once you get into it, it really isn't that bad, and better to know its for sure an injector than spending the money on a new one, going through the same process and finding that it wasn't bad.

MaK92-4RnR

yeah. Tomorrow im going to dig into it. Im gonna replace her wires first. Im hoping its not the fuel injector.

MaK92-4RnR

So wires were replaced, also swapped a coil pack. Still getting p0306. Any ideas? Fuel injector?

MaK92-4RnR

replaced the fuel injector. problem solved...

nicheel

Just wanted to see if its still running ok? I have a 99 4Runner and I am going through the exact same thing. My code comes on and the truck shakes, but it doesn't happen all the time. I may drive it 20 miles, shakes for 5 miles, then goes away.

Should I start with the compression test or go straight to the swapping the injector?

MaK92-4RnR

Still runs like a champ.

You're having the same problems I did with my cousin's 4Runner. its the injector. it was very intermittent until it finally just gave up the ghost and was having issues all the time.

nicheel

Thanks! I wanted to make sure that was the fix before I start the job.

P0133 - O2 replaced, MAF cleaned, New Air Filter
P0306 - Spark plugs - SP Wires - and Coil replaced, Fuel filter replaced.

Symptoms - Runs fine when she's cold, then starts to shutter when she gets warm - 15-20 miles.

nicheel

i forgot to ask. Did you use Toyota injectors or aftermarket? And do you know if Denso makes Toyota injectors?

MaK92-4RnR

just used napa injectors. its worked flawless since

Ladythump

I have the same problem and I'm wondering how much a garage will charge to change the injector?
Also, if I don't change it, how long will the truck keep running without the change?

maachine

hahaha. sorry after reading each post, this was funny