Idle Issue

[Sandytoes]

Hello all,

I am a long time snooper on this site. I am on my second 4runner and since day one always looked to this site for direction but never registered. I have now ran into a problem that I need input. I have searched to no avail.

About a week ago my 99 4runner V6 4x4 Limited would idle rough upon start up when the engine is warm. It would also throw a code, P0301 which is a misfire in cylinder one. I replaced the spark plugs and wires with NKG to no avail. I found that others who had this issue replaced the fuel injector and that corrected the issue. I purchased an injector from my local auto parts store and just got finished installing. I started the 4Runner and drove around the block with no issue but when I parked it the idle is uneven and I hear a low deep humm from my intake box upfront. I checked for any hoses I may have forgotten and all seems together and tight. Any ideas?

 

[CO_FlyFisher]

Mileage?

Could be a lot of things. MAF, TPS, fuel filter, or fuel pump would be on the top of my list to investigate next. Hopefully you didn't waste a bunch of money on that injector without checking these other things out first.

 

[Sandytoes]

Thank you for the response. It is appreciated!!!!

I did not have the humm prior to the fuel injector change. The issue I had before was when starting the rig while the engine was warm the idle was very rough and I would get the code P0301 related to cylinder 1. I am no longer getting that code nor am I having an issue with a very rough idle. I did clean the MAF sensor when changing the plugs.

What I am experiencing now is a very slight idle change from 600-700 and a deep hum coming from the air intake box. When I open the box and remove the filter it gets louder and I feel a deep vibration when my hand is on the box.

I am pretty sure I put all back together but maybe I missed something. May need to disassemble and reassemble. Hope someone here had a similar issue before I break the wrenches back out.

 

[Sandytoes]

By the way, my fuel pump, filter and MAF is fine. Will test the TPS next but can't think why that would cause a vibration in the air box.

 

[Sandytoes]

By the way, my fuel pump, filter and MAF is fine. Will test the TPS next but can't think why that would cause a vibration in the air box.

 

[Sandytoes]

I took the meter to the TPS and it turned out fine. What I did notice is when I disconnect the harness to the IAC the noise/vibration went away. I removed the IAC and there was very minimal deposits. I cleaned with MAF sensor cleaner and also tested the movement by applying power to it. It did turn both directions.
Any ideas?

Thanks you in advance again for your time and efforts!!!

 

[ShooterMcGavin]

I took the meter to the TPS and it turned out fine. What I did notice is when I disconnect the harness to the IAC the noise/vibration went away. I removed the IAC and there was very minimal deposits. I cleaned with MAF sensor cleaner and also tested the movement by applying power to it. It did turn both directions.
Any ideas?

Thanks you in advance again for your time and efforts!!!

That would have been my suggestion to fixing the warm rough idle. Sorry, I can't help more than that.

 

[Kenworth]

If it did not make noise b 4 you have hooked up a vacume line in wrong port
Or did not hook one up double ck everything

 

[Sandytoes]

Thank you Shooter for your input!!

CO_Flyfisher, I disassembled and reassembled and with the help of the Hanes manual and Toyota Service manual reassembled. All looks to be tight and in its proper place. I also switched out the IAC from my 97 4runner to no avail. I wonder if the issue is in the wire harness? I know it is brittle as I noticed when I replaced my gaskets. Will check IAC voltages next I guess.

Can someone to me a big favor, run out to your rig and after its warm check your intake box and see if you have a slight vibration or hum coming from it. My other 97 is out of commision and I want to be sure I am not chasing something thats nothing. I have a habit of doing that :fish:

Again.....Thanks a bunch!!