Matt in AR

Folks - I have had it and can't figure this out. I have a 98 4runner, 3.4 V6 auto, 4x4.

Bottom Line: About 6-7 weeks ago after returning from a 600 mile trip, I noticed that when ideling (like at a red light), my rig runs very rough. I mean you can see the shifter vibrating & the coffe sloshing in the coffee cup in the dash cup holder rough - and this rig is an auto. To date, I have tried the followig: tune-up, replace intake manifold gasket, new fuel filter, new 02 sensor, cleand MAF sensor, and checked all hoses for vacum leaks and run a vac test. Per mechanic, injectors & flow rate are good. I have paid to run the codes and other than resulting in the manifold gasket replacement, the codes say nothing that helps. Deck-plate mod is closed and has been closed for over 5 months.

My gas milage has gone way down and whatever is or has happened can't be good. Does anybody have any thoughts on what else to try? The mechaic says soemthing about rying to see if the IAC is blocked - whatever this is?

Any thougths?

Thx,

mr

MTL_4runner

If it only stumbles like that at idle and you get no other issues while driving on the highway (such as hesitation, misfire, etc), then I would say that you definately need to do a thorough cleaning of both the IAC and the throttle body itself. You should also consider doing an good Seafoam treatment to ensure there isn't any other carbon buildup causing issues (hotspots, preignition, etc). You should run at least 2 cans of Seafoam through 1/2 tank of gas and then run another full can through the engine itself via the PCV or vacuum hose (only use 1/3 of a can at once and repeat it 3 times).

Here's a link (99runner4me did a great job on the writeup!):
https://www.yotatech.com/forums/f123/re-3-4l-v6-hard-start-hot-cleaned-iac-pics-92286/

mkgarrison5

couldnt you just spray injector cleaner through the intake while running to help solve this problem? i used that on jeeps numerous times and it helped a lot with idling and even gas mileage...

MTL_4runner

As long as it was converter / sensor safe, yes, you certainly could. Without knowing the actual active chemistries of all the different cleaners (ie Seafoam, BG44K, aerosol cleaners, etc) it's really hard to say which will work better than others. I suggested Seafoam because it's fairly cheap and has been proven to work very good (I've done it quite a bit myself and it works well).

mkgarrison5

yeah i agree with you on the seafoam but what i was asking is that on top of the seafaom couldnt he spray some injector cleaner through the throttle body to get some of the other areas not covered by seafoam? like the CRC carb\ injector cleaner...

mkgarrison5

oh and i used almost a whole can at one time in the pcv.... it did well, it smoked up my yard and my grandpa's yard haha but it worked

MTL_4runner

Absolutely......again just check that it's sensor safe.

mkgarrison5

i noticed when i took my air tube off that it was grimey and dark colored inside the intake man. but of course i didnt spray the cleaner in there bc i something came up and i forgot.. bc like him my idle is rough but i get good gas mileage with no issues at all. its very smooth other than idle

MTL_4runner

You might consider following the same advice I gave him above. Sometimes you actually need to disassemble certian parts to clean them, not just spray carb cleaner in and hope it somehow works again. Have you cleaned your throttle body at all?

Do this first....
http://www.4x4wire.com/toyota/mainte...tenancep5.html
They say use a rag but I just use an old toothbrush and it works great.

mkgarrison5

no i havent yet but thats where i would spary injector cleaner in while the truck runs. it will take that mess off.. well first i would wipe out what i can just to keep it out of the intake and the spary on idle till it chokes and hit the gas and burn the rest out.. works wonders for jeeps. but never done it with the yotas

MTL_4runner

The better way is to take the intake tube off. Clean the throttle bore and plate really well with liberal amounts of cleaner and the old toothbrush (also spray it into the air bypass.....its a hole just in front of the throttle plate and it's also where the IAC draws air). Make sure to open up the throttle plate completely while you're scrubbing with the toothbrush (helps to have a helper floor the gas pedal while you're doing this). Once everything looks spic and span, reinstall the intake tube and start the engine with your foot completely to the floor. Once the engine starts, hold it at about 2500-3000 rpm until the smoke stops coming from the exhaust. You can spray more in while it idles after, but it's really not necessary at that point.

mkgarrison5

yeah i know to take the plastic tube off to where the butterfly is exposed.. clean out what you can with a rag and burn the rest out.. i am curious if this is a good idea for me bc i have brand new plugs in there. should i wait till the plugs are in need of changing??? in the past with jeeps i could do it anytime and not worry about the plugs

MTL_4runner

Same with Toyotas, no issue there.....cleaning the TB alone won't foul the plugs.

mkgarrison5

thanks jamie

Matt in AR

Thanks fellas - I can't check the site from work so I had to wait until I got home.

I will try some of these tips.

mr

grimpy

What the heck... My shifter is always vibrating... I thought it was normal?