tacotacoma96

Well this problem has been buging me for a while. If I cant figure it out here i'll have to go to the dealer. So, when my 4runner is cold or it hasn't been cranked for a few days it does this
Its a '99 with a 3.4 V6. After you give is some gas it'll idle just fine. Have a few ideas but Not really pinned it yet. Any info will be helpful

Gregs94Toy

Sounds like it's not getting fuel perhaps? Mine does something similar when it's hot..

j2the-e

Try cleaning the idle air control valve

StewsRunner

iTrader: (1)

Could it be the dash pot? You said if you give it gas it'll hold an idle so if the dash pot is broken it'll do that, I think. . .

tacotacoma96

Thanks everybody. I'm gonna try to clean the idle air control valve tomorrow. Thanks for all the ideas

brianh699

Your video doesn't seem to work, if you are having starting issues when cold I would suspect a temperature sensor or switch. I'm not real familiar with the 3.4 does it have a cold start injector? If it does I'd check that.

tacotacoma96

The video is back up.

tacotacoma96

Sorry for the wrong video but I found the problem. Turns out j2the-e was right. Took off the idle air control valve and gave it a good cleaning and now she cranks when cold without dying. It seems to rev about 1400RPMs until you put in gear, them it stays about 1000RPMs. Just wondering what other 3rd gens idle at.

j2the-e

Thats a little high. Make sure the coolant is flowing through the iac valve. Clean the throttle body and disconnect the battery so it can re-learn

tacotacoma96

Yeah we cleaned the throttle body when we cleaned the IAC. We also disconnect the battery when we did it. when we disconnected the hoses some antifreeze came out, so I'm sure its getting antifreeze. I got a K&N on it. You think that's whats causing it to idle a little high. I'm thinking once the computer learns it should idle right again.

Gregs94Toy

I did the exact same thing this morning although no battery cable restart, does that HAVE to be done? Mine idles crazy smooth now and oh boy the butterfly valve in the TB was stuck shut during extended idling causing the pedal to stick at stop lights pretty bad.

tacotacoma96

Did you clean the throttle body while you did it? I did because mine was crusted with a little bit with carbon. The reason I disconnected the battery was I had to unplug the MAF sensor. If I didn't it would throw a code. Here's the video I went by when I did mine. It's a Tacoma but its got the same motor as mine

DRCOFFEE

650-750 rpm when warm. Your IAC valve is still carbon coated and now stuck partially open. Make sure you dont use a harsh cleaner. Use MAF electronics cleaner.

Here's what fixed mine. Do this with the engine warmed up so the valve will work to close itself. You leave the MAF electrical plug connected but disconnect the intake tube from the TB, it wont meter air moving and allow the engine to start and then die. So now, using MAF cleaner, shoot a good amount (don't flood it) into the hole in front of the butterfly valve to loosen the carbon in the IAC pintle. Start the engine right away while its still liquid. It will roar and then die. Do it a few times until all the crud has been sucked past the IAC. Button it back up and see how it idles. It took me 3x to get it to settle back down to 700rpm. I really wish Toyota had designed it better, like putting the orifice to the IAC up on top instead of at the bottom. I wonder if capping the PCV line to the front port would cause any problems. It goes to the drivers side valve cover at the back side. Seriously, i think I am going to just Y connect both lines into the PCV valve and keep the crud behind the throttle plate. That was the way my 99 corvette LS5 was setup. Both lines ran to one PCV valve on the passenger side. And it worked just fine. I'll have to rethink this idea as there wouldn't be a fire stop (PCV) on the drivers side line

Edit: so to plumb the drivers side PCV line behind the TB plate, there would need to be a second PCV valve. The PCV could be installed right off the hard line behind the TB. Then route the hose to the passenger side PCV line between the factory PCV and intake.its still metered air as they are both behind the MAF. Does anyone see a problem with this setup?

Left side of the photo below


Well, the passenger side line must be a two way port. At idle it flows away from the TB and at partial throttle, it flows to the TB. If both are under vaccum, would it negatively affect the engine?

tacotacoma96

Well the 4runner decided to fix itself today.I took it to school today and it idled steady at 1400RPMs. After driving about 15 miles, It jumped back down to about 700RPMs, and been that way ever since. Guess the computer just had to relearn. Well all I can say is I hope this thread helped some other people out. Also thanks to everybody for all the info I needed to fix this problem thats been bugging me since I bought the 4runner.