darth brian

so ive been diagnosing my fiancees 98 4runner 2wd 4cyl because her check engine light came on. codes it spit out were p0300 (random misfire0 and p0303 (cyl 3 misfire).

There is a noticable loss of power and vibrates really bad at idle.

Ive replaced bad spark plugs and bad wires and also checked the resistance on the coil. cleared the code and the next day the light came back on. now its only spitting out p0303.

Only thing i can think of now is the injector on cyl 3 is bad. But i dont want to spend the money on one and spend the time replacing it if its not the problem even though im pretty sure it is. just thought id post on here and see if you guys had any other ideas of simple things i can check or test.

thanks

Bojangles

Im willing to bet its an injector. I had this problem with my 94 Pickup,
It was a bucking missfire and it just felt like it was running on 3 cylinders.
It had a considerate loss in power,
And it shook very bad while driving.
I found 4 offbrand injectors online somewhere for like 80 bucks. They had a 100,000 mile warranty so i decided to try it and they have worked perfect.
If you do not have the money for this, The only thing i know to tell you is pour two bottles of lucas fuel injector cleaner in an empty tank and fill it up with Premium gas and let it idle for a little while.

One way to tell for sure if its the injector on #3 is get a compression tester and turn the engine over enough to pressurize that cylinder and when you release the pressure smell the air that comes out. If you dont smell gas then its most likely your injector.
If you do that test, and it is the injector...
My advice is go ahead and replace it because i wouldn't let that cylinder run dry like that. But maybe thats just me.

Good luck, Hope you figure it out.

JakeBhs09

I am having the same problems on a 99. I was told to try and put a mechanics stethoscope on the injector body and listen and compare it to other injectors. I have been told if it is a faint sound or silent than it indicates the injector is bad. Let me know how it works out.

darth brian

i work part time at my local autozone and can get an injector for 90 bucks. do you guys think i should replace all 4 while im in there?

prorunner

You could take your injectors and get them tested first. Also, I haven't had personal experience but I hear good things about these guys http://www.witchhunter.com/

KU_MechE

I just did this on my car. You need to pull all the injectors and test the resistance with a multimeter. Check the measured resistance against the manual. The ones that are within spec are probably ok, but i'd recommend sending them to witchhunter to have them flowtested/cleaned/rebuilt. They'll put all new seals, 0-rings, filters on them after ultrasonically cleaning them. The turnaround time is awesome and the price is only about $20ea.

fisherm

The injector resistance on my '99 4runner runs around 15 ohms. You'll want to check it cold and hot. I had one that checked out fine cold but when it got hot the coil broke down.
Had a misfire code because of a coil pack once too. They're easy to swap out to another bank and see if the problem goes with it.

Bojangles

Id go ahead and replace all of them if you were there.

You know, cause you get that 20% discount

KU_MechE

I disagree. Assuming you have one faulty injector already, you'd spend $270+tax to replace the other 3. That's a lot of money to replace something that's not broken.

I'd still recommend sending the other 3 good injectors to Witchhunter for about $60 for cleaning and flowtesting. They'll confirm proper impedance too.