I have a 1999 4Runner 2wd V6; Rough idle, only when Warm. Cold idle has no problems (live in LA so, Cool odle!)... OBD read 0300 and 0301, multille misfire and misfire cylinder#1. I am still having the rough idle after doing all of the following:
Replace Cyl#1 Coil, wireset and all 6 plugs. Improved all around performance, but not the idle issue.
Then Replaced PCV Valve and thoroughly cleaned MAF sensor, Idle Air Control (IAC) Valve, intake hoses and Throttle body. Truck running GREAT, but still have the rough idle when warm. I dont have any way of testing the new coil...

Could I have a BAD, New, Coil? Or what should attempt next? Fuel injector and new IAC valve are a little expensive to NOT be sure of a fix.

 

I had a similar issue in my 99 SR5. At first it cold idled fine but as soon as it reached op temp it stumble and idled rough. But it progressed to poor driving and then limp mode. My problem turned out to be a bad fuel inject #4. I swapped out all three on the drivers side #2, 4, 6 at the same time because it was such a bitch to get to. I can do the others without removing the intake at a later date. I had code P304

As it was explained to me, as the engine heats up the electric coil inside the injector separates and breaks the connection to control the injector signal.

 

That makes a lot of sense, but costs A LOT MORE CENTS!
I was hoping to avoid replacing fuel injectors, but that may be the only option.
Anybody know a way to test a fuel injector?

Going thru all the other steps has the truck running Beautifully otherwise!

 

This man has it right

 

Ok, I am starting to buy tools to keep doing stuff on my own. Recommendations for an injector tester and compression test system?

 

RockAuto has some Reman. plugs for only $40-$50. What brand should I use for injectors if they tend to go bad on 4runners? Remanufactured or NEW?

 

The GB reman fuel injectors have been great. They were only $30 each. Be sure to get the correct colored injector. There is no way to test the injectors on the truck. If the coil is broken, you may get good resistance cold but then zero when hot. Its going to be intermitant. Considering the time to R&R the injector, its smart to replace them all at the same time. That way they are all new and balanced. Dont forget to twist the injector before pulling them out and lubing the o-rings before installing the new ones.

 

Thanks. Any engine grease will do for lube or should i use a particular kind for the injectors?

 

Vaseline works fine. You dont want to use anything that will degrade the o-rings.

 

Good to know. Can I do that with more that just the injector rings?

 

What do you mean?

 

I just mean as a lubricant for different gaskets. For example, I need to change Trans filter/gasket soon. Just lube with Trans fluid or something like vasoline?

 

use the fluid you are replacing in that case.

 

Thanks.

 

I bought an OBDII scanner for $25, have 1 new OEM injector (for now) on the way to change out from Cyl#1. Scanner is only showing P0301 now, No P0300.
I am going to test the new Coil and Plug that I put on Cyl#1 before changing the injector.
I will check back in a few days when I get this done!

 

New injector in Cyl#1 fixed my problem!
Now this 99 is like a new truck! New plugs & Cleaning out the throttle body and IAC really made a huge difference!

 

Its a good feeling to fix the truck affordably and learn something along the way. Kudos

 

I appreciate the help and Yeah it is! Haha