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Ted Ritter
Ted Ritter, Toyota Master Tech
Category: Toyota
Satisfied Customers: 4283
Experience:  Toyota Master Tech, ASE Certified
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I replaced my 2001 Sienna valve cover gasket, the back one,

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I replaced my 2001 Sienna valve cover gasket, the back one, and I had to take off a lot of parts, including the throttle body, which I left hooked up to all the hoses and gently moved it to the right during the job. While I was there, I sprayed some throttle body cleaner in both ends. Now, the idle in park is 1400-1500 and while I'm driving its about 900. How do I fix this? What should I look for? As far as I can tell, there are no vacuum leaks, but I'll take another look at the EGR valve which I messed with during the gasket replacement.

Hello and welcome,

Double check to make sure the throttle body gasket is installed. If it is disconnect the battery fro a minute and drive it around for a few minutes and see if the idle goes back to normal. Make sure the idle air control valve vacuum hose is connected, it's the one in the middle, the other two are for coolant and also check that the electrical connector is on.

Customer: replied 5 months ago.
Gasket installed. Disconnected Battery to reset ECU and drove it...same. The hose is definitely on and not split...I took off the connector and put it back on...where to from here?

Thanks for the reply,

Earlier you mentioned something about the egr valve, did o you ust remove and put it back on? A stuck egr valve won't cause the idle increase it would actually make the engine stall. A couple of other things to check but I have a quick question first: Does this engine have the twin throttle body? If so, take a look to make sure the both throttle plates close all the way then the other thing is that it's possible that for some reason the idle air control valve is partially stuck open or, and this is also very important, check the engine coolant temp sensor connector, check that the engine comes up to correct temperature the way it should at about 1/2 way on the gauge.

Customer: replied 5 months ago.
Found a broken hose commection on back of air filter housing...egr solenoid nipple broken off..can this be it?

Maybe, it's obviously not the way it's supposed to be, not sure by what you mean egr solenoid nipple, is it the egr vacuum switching valve? Can you upload a picture of this?

Customer: replied 5 months ago.
OK, spent $69 on the egr you predicted it didn't lower the idle rpm...twin throttle...I'll take it apart again and see if there is any sticking...going to take me, an amateur, a while.Temp works perfectly now, although the car sat for 9 months without anyone driving it due to a smashed windshield that I just replaced. For the first few miles of driving the temp gauge went all over the place and then settled with no more problems...can a bad thermostat cause high idle? A couple of years ago I replaced the radiator myself, so I know that the correct coolant and mix % is spot on.Getting frustrated, but appreciate the help.

That's not the egr valve solenoid, it's for emission control Evap system) If the thermostat is stuck open the engine will take a long time to get to operating temperature so yes it can cause the fast idle because the temp sensor is seeing it as such and sends the information to the computer which controls the idle air control valve. Eventually the engine should heat up even with no thermostat. If you remove the throttle body again then check the idle air control valve, remove it from the throttle body and check to see if it's stuck open.

I haven't yet asked this but is the check engine light staying on when driving?

Customer: replied 5 months ago. are a man with more patience than I..ha ha...No check engine light...the car actually drives great with the new plugs, air filter, egr valve and I stopped the oil coming out of the back valve cover.Alright, I'm determined to learn something here... I'll remove the throttle body...gonna take a while---but that is where it probably is gonna get fixed, although there is a small voice saying I should have swapped out the thermostat the time I changed the radiator...

Sounds good, let me know when you get the idle control valve off and send a picture of the inside of the valve. If you have any doubt about the thermostat go ahead and replace it. make sure both throttle plates close all the way

Ted Ritter and 2 other Toyota Specialists are ready to help you
Customer: replied 5 months ago.
Ted,It's solved. I first took the throttle body off and tried to remove the screws for the valve...not possible. So I sprayed everything again with throttle body cleaner and especially down the hole to the inside of the valve. Screwed it all back improvement. Instead of drilling out the screws and then probably having to replace the valve (it was looking like 140 to 160 dollars), I bought a used throttle body on eBay for 90 and put it in. Problem solved! Thanks for your insightful help.