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Other DIY's exist for these tasks, but this guide explains how to replace all three gaskets and clean everything at the same time - which you might as well do if you're going to invest the time to do any one of these tasks. This guide is very detailed: it discusses cleaning and replacing the gaskets in the idle air control valve, throttle body, and intake manifold. It also shows how to disassemble the throttle cable (for those of you with a 2003 or 2004 model).

My car is a 2003 Corolla with ~126,000 miles on it.

Items you need:
Intake gasket (Toyota part # 17171-22060)
Throttle body gasket (Toyota part # 22271-0D030)
Idle air control gasket (Toyota part #22215-7A680)
3/8 drive ratchet
3/8 drive 10mm socket
3/8 drive 12mm socket
3/8 drive extension (3 and 9 inch)
Regular phillips screwdriver
Needle-nose plyers (or similar for removing hose clamps)
2 adjustable wrenchs or 12mm spanners
Towels/rags/q-tips
Throttle body and air-intake cleaner


Let's get started:
These are the gaskets:

Secure the parking break and pop the hood

Remove engine cover (use 10mm socket). If your cover has never been removed, you may have plastic clips holding the cover on. I removed and replaced these with screw bolts years ago. This DIY by JasonA shows you how: http://www.toyotanation.com/forum/132-9th-generation-2003-2008/309425-diy-replacing-engine-cover-plastic-retainers.html


Remove the duct hose that connects the air box to the throttle body. To do this, you need to loosen the 10mm clamps and pull the duct hose off.

There are 3 breather hoses that connect to the throttle body. Remove them:
Hose #1


Hose #2 (connects to the PCV valve in the back of the engine)


Hose #3 (I did not completely remove this hose, I just disconnected it from the throttle body)

If your Corolla was made in 2003 or 2004, you need to remove the throttle cable.


Use 12mm spanners or wrenches to crack the nuts as shown. I only loosened the top nut so when I reinstalled the bottom nut would still be in place and make sure everything is still set correctly.

When you've loosened the top nut enough, slide the cable out

Remove the electronic connectors on the front and bottom of the throttle body


Remove the bolts from the top of the throttle body (use 10mm socket)

Remove the 4 bolts surrounding the throttle body (use 12mm socket). The top bolts are easy to round off, so be careful. I had to use a bolt extractor.

Remove the metal connector that bridges the gap between the intake manifold and the throttle body. One of the 4 bolts you removed in the previous step holds this part on. Remove the other bolt.


The throttle body should now be only connected to the car by 2 coolant lines (which connect to the back). Slide the throttle body off to get better access to these coolant lines.

Remove the coolant lines. Mine were stuck on pretty good. I used a flathead screwdriver to force them off. Small amounts of coolant will spill when you do this - it's best to have a towel to catch the spillage. Prop them in an upward position so that you don't loose more coolant, or put bolt screws in the tubes (or use similar object to plug it).



Remove the throttle body

Remove the 3 screws holding the idle air control valve (IACV) to the throttle body (careful, these screws are soft and strip easily)

Separate the IACV from the throttle body. You can see the old IACV gasket now.


The black section of the IACV can be removed to allow for a deeper clean. A specialized tool is needed to remove these screws (I've seen it on forums somewhere, but I can't seem to find the link). You can also drill the screws out or use a hacksaw to make an indent (and then use a flathead on the indent).

I replaced these with phillips screws

Remove the old gasket and clean the IACV with throttle body and air-intake cleaner. I used a lot of q-tips. If you remove the black section you can spin the sensor and clean it better. You can also clean the throttle body's butterfly valve at this time.

You can also remove the old throttle body gasket

Remove the intake manifold. To do this, remove the bolts and nuts on the front. There are 5 bolt screws and 2 nuts to remove. You will need a 9" extension for this. There are black clips connected to the intake manifold, but after removing the 2 nuts you can just spin them off to the side.



Slowly remove the intake manifold. As hardtopte72 states in his guide
"When removing take note of the hidden vacuum line behind the intake and remove it."
Take his advice. I've circled the location of the hidden vacuum line. I also circled one of the black clips after it has been unhooked.

Remove the old intake gasket

At this point, I took a significant amount of time to clean the engine (I rarely disassemble the car this much, and it allows easy access to clean the engine bay. I also cleaned the intake manifold and installed the new gaskets.



When you've cleaned everything and installed the new gaskets, it's time to reassemble the car. First, align the intake manifold to the front of the car and slide it back on. Connect the hidden vacuum line in the back. Then replace all the bolt screws and nuts holding the intake manifold on (there are 5 bolt screws, 2 nuts, a metal connector, and 2 black clips). Reconnect the IACV to the throttle body, and bolt it back onto the car (don't forget the other metal connector). Reconnect 2 coolant lines, 2 electrical connectors, and 3 hoses to the throttle body. Reconnect the duct tube to the air box and throttle body. Verify that everything is reconnected properly. Turn the car on and check for noticeable vacuum leaks. When you are confident that everything is reassembled properly, re-install the engine cover and admire your hard work. Be happy that your car will probably never throw a P0171 code.

 

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2005 Corolla CE
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Great DIY. Nearly exactly what I was going to do in my BIL's Corolla.

Only thing I will say is it really only applies to the 2003-2004 as the steps for TB removal, cleaning, and intake gasket replacement on a 2005-2008 are already in the existing DIY's.

I will add this to the sticky.

:thumbsup:
 

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2004 Corolla
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Great instructions, Shatter. Wish I'd have read this a week or two ago. I replaced the intake gasket and IACV but realized that I'd forgotten to purchase the throttle body gasket. Ended up swiping some gasket sealer on top of the old gasket. I did clean the throttle body with cleaner and a toothbrush but didn't even think to clean the IACV valve. Oh well, she runs better anyway and no more codes. I also replaced PCV valve, plugs, valve cover gasket, engine oil change and transmission drain.
 

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Just a couple of tips:

1> It is not necessary to remove the throttle body from the intake nor the IAC from the throttle body... unless you're completely anal about inspecting and cleaning these items.

If you want to do a quick gasket swap you can simply leave the throttle body (and its coolant hoses) attached and then just swing it out of the way. This gives you plenty of room to clean out the intake (and throttle body with it still installed to the intake) and to swap out the gasket and clean the gasket surface.

2> You really don't need to undo the throttle cable, and if you do want to remove it you can unbolt the bracket from the Throttle Body - this way you don't risk messing up its adjustment, however it's not exactly difficult to do it like in this write-up if you're careful.

3> There shouldn't be any real reason to replace the IAC gasket if you choose to remove it for cleaning - unless of course you somehow manage to damage it somehow. Those gaskets usually stay really thick and I've never had any issues with these sealing back up.

4> This would also be the perfect time to remove the Mass Air Flow sensor and give it a good cleaning as well!

My only complaint about the write up is the size of the pictures. You may want to consider resizing them a bit smaller so that they fit on the page.

Otherwise... EXCELLENT JOB!
 

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Shatterpulse, I've been waiting for something like this to come along. I believe I owe you a tasty beverage of your choice. Thanks for this, and glad you're an official part of the forum.
 

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Own a 2003 Toyota Corolla LE. Am a newbie, and a novice when it comes to mechanics.

The IAC Valve position sensor has two M4 screws (~1", 24.3 mm total length) that have soft, poorly formed star heads on them. These are supposedly not supposed to come off the IAC Valve body. I've seen some folks cut a horizontal line on the head first to take them off and reuse. They strip easily. No part number.

The 3 M5 phillips Throttle Body screws = Toyota Part #90079-10012 , .881" or 22.3 mm total length
The 2 M4 phillips throttle position sensor (?) screws = Toyota Part #900079-11057 , ~1/2" or 12.7 mm total length

I think the IAC Valve = Toyota Part#89452-20130 and runs between $100-$225
 

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2003 Toyota Matrix
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Own a 2003 Toyota Corolla LE. Am a newbie, and a novice when it comes to mechanics.

The IAC Valve position sensor has two M4 screws (~1", 24.3 mm total length) that have soft, poorly formed star heads on them. These are supposedly not supposed to come off the IAC Valve body. I've seen some folks cut a horizontal line on the head first to take them off and reuse. They strip easily. No part number.

The 3 M5 phillips Throttle Body screws = Toyota Part #90079-10012 , .881" or 22.3 mm total length
The 2 M4 phillips throttle position sensor (?) screws = Toyota Part #900079-11057 , ~1/2" or 12.7 mm total length

I think the IAC Valve = Toyota Part#89452-20130 and runs between $100-$225
These 2 M4 screws 24.mm or 12.7mm??
 

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Does the black section of the IACV NEED to be taken off? I have a five pointed screws there. Searched high and low for the bit but couldnt find it.

The toolkit mentioned ^^^^ also didnt have the required bit. Hacksaw/SST from Toyota seem to be the only way of removing them.
 

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Does the black section of the IACV NEED to be taken off? I have a five pointed screws there. Searched high and low for the bit but couldnt find it.

The toolkit mentioned ^^^^ also didnt have the required bit. Hacksaw/SST from Toyota seem to be the only way of removing them.
No. Additionally, removing the black portion may introduce a new problem if you don't align it correctly on reinstallation. There is no carbon on the electrical side. Since IACV cleaning is a fairly delicate process anyway, I would say to leave it in place and just clean the valve.

It was also nice to reaffirm my theory on duty cycle being used as a measure to detect IACV condition. Post cleaning, your car idled perfectly at 20% duty cycle, where as before it would buck and likely stall. Not bad for a $5 in throttle cleaner.

Also worth mentioning to those who do this repair. Don't forget to reinstall the IACV gasket before reinstalling the valve. It happens to the best of us if distracted.
 

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Isn't the IACV gasket quite important to prevent coolant from entering the intake and hydro-locking the engine?
 

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Isn't the IACV gasket quite important to prevent coolant from entering the intake and hydro-locking the engine?


We had cleaned the TB/IACV, zipped up the car and then saw two gaskets, the old one and new one. Hardtopte72 is only adding that you should double check the gasket before putting everything back.
 

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I got that, its just that i had read a post where someone improperly installed the IACV gasket and ended up ruining the engine via hydrolocking it with coolant. My question was whether that is possible
 

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I got that, its just that i had read a post where someone improperly installed the IACV gasket and ended up ruining the engine via hydrolocking it with coolant. My question was whether that is possible
It's possible to get some coolant into the engine through the valve if you left the gasket off, but most would probably leak out.

There is only one way to find out lol.
 
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