o ring fix solved high idle

Joined
Nov 28, 2006
Messages
593
Location
Leesport, PA
So I went ahead and tried the o ring fix on my iac valve to cure very high rpm's on startup. It would rev up to 1800+ rpm and slowly drop to normal in about 4 minutes. I had read that the fix works for some, but not for others, and I have an idea why.
I initally tried to remove the valve with the TB still on, but immediately stripped the lower screw. I then sourced two bolts to replace the screws, and removed the TB to get at the stripped screw. A vise grip solved it, and I am glad to have bolts in there instead of soft headed phillips head screws.
Anyway, I pulled the valve off and disassembled it per the article here: http://web.archive.org/web/20010627164802/www.safari4x4.com.au/80scool/tech/fast_idle/fast_idle.html
I noticed when I put the two o rings on the shaft, and reassembled the valve, that the spring wouldn't seat right on the o rings and would try to push over them. Upon inspection I noticed the spring is supposed to be seated back farther than where the o rings sit in the below picture.


Once I stretched the o rings and seated them where the red arrow shows, the spring sits where it is supposed to and the o rings effectively space the spring out. This has solved my high idle, it now revs to about 1200 for a second, and quickly drops to about 900 for a minute or so, then to around 700. I can now actually get in and drive without waiting for 4 plus minutes for the idle to lessen. The startup rattle is also gone. I think that a lot of people were placing the o rings where the picture in the article shows, instead of further back on the shaft.
 

MaddBaggins

Remember the KnightRider!
Joined
Feb 22, 2005
Messages
3,548
Location
The Old Pueblo
Did that more than 2 years ago. Been working great. I went from 1600-1700 startup RPM down to 1200 at startup with one oring. I tried 2 orings and it went down to something like 700-800 and I wasn't comfortable with that so I went back to 1 oring.
 
Joined
Aug 8, 2003
Messages
9,024
Cool. Planning to do this one. O rings taped to my tool box since, um - Fall of '06 or so...

Thanks for the input!


DougM
 
Joined
Nov 28, 2006
Messages
593
Location
Leesport, PA
it is a very worthwhile fix in my opinion. The high idle and 4 minute wait until I could put the rig in drive was getting really old. I forgot to mention that the three screws that hold the valve together can be a bugger. They are loc tited in from the factory. Make sure to get a proper sized screwdriver and have the valve in a vise for stability. I still managed to mangle one of the screws, and had to put it back on with a vise grip and a good dab of loc tite.
 

MaddBaggins

Remember the KnightRider!
Joined
Feb 22, 2005
Messages
3,548
Location
The Old Pueblo
I recall having some trouble with the screws also. I had to use a hacksaw blade to cut a slot in the head of one so I could use a large flat head screwdriver to remove it.
 
Joined
May 10, 2006
Messages
558
Location
6005 ft. Smoky Mtns. Idaho
So I went ahead and tried the o ring fix on my iac valve to cure very high rpm's on startup. It would rev up to 1800+ rpm and slowly drop to normal in about 4 minutes. I had read that the fix works for some, but not for others, and I have an idea why.
I initally tried to remove the valve with the TB still on, but immediately stripped the lower screw. I then sourced two bolts to replace the screws, and removed the TB to get at the stripped screw. A vise grip solved it, and I am glad to have bolts in there instead of soft headed phillips head screws.
Anyway, I pulled the valve off and disassembled it per the article here: http://web.archive.org/web/20010627164802/www.safari4x4.com.au/80scool/tech/fast_idle/fast_idle.html
I noticed when I put the two o rings on the shaft, and reassembled the valve, that the spring wouldn't seat right on the o rings and would try to push over them. Upon inspection I noticed the spring is supposed to be seated back farther than where the o rings sit in the below picture.


Once I stretched the o rings and seated them where the red arrow shows, the spring sits where it is supposed to and the o rings effectively space the spring out. This has solved my high idle, it now revs to about 1200 for a second, and quickly drops to about 900 for a minute or so, then to around 700. I can now actually get in and drive without waiting for 4 plus minutes for the idle to lessen. The startup rattle is also gone. I think that a lot of people were placing the o rings where the picture in the article shows, instead of further back on the shaft.
Aha, so that's where the O rings are supposed to seat...say, do you remember what size, and thread pitch, the bolts you sourced were. It would be so easy to remove the IAC with hex bolts holding it in.
 
Joined
Nov 28, 2006
Messages
593
Location
Leesport, PA
Unfortunately I don't know the correct size. I stopped at a specialty fastener store, popped open the hood, and took out the top screw. Had the parts guy bring me up two bolts of the same size. The top screw is really easy to get at, so you should be able to match it in size by stopping at a fastener store.
 

MaddBaggins

Remember the KnightRider!
Joined
Feb 22, 2005
Messages
3,548
Location
The Old Pueblo
I watched mine this a.m. to refresh my memory.
With one oring, mine starts up at 1200 for a couple seconds, then drops to just a hair under 1000 until its all warmed up. After that, it's sits around 500-600 stopped at a red light in drive.
 
Joined
Jan 25, 2008
Messages
1,608
Location
Opelika, AL
The article states to "Be sure that the three small phillips head screws are secure. A drop of loctite is good insurance. Should one (or more) come loose, it/they can be ingested by engine with catastrophic results." I'm not seeing it. How could these screws get inside the engine? The valve would suck them in?

I'm having this problem and it worried me when I first got my cruiser. I posted up and I was told this high idle is normal as you or the article have also stated. It looks simple enough but the thought of loctite and little screws has me a little nervous. I wonder how much a new ISC would cost?
 
Joined
Nov 28, 2006
Messages
593
Location
Leesport, PA
It would seem hard to me for a loose screw to getr sucked in via the small valve hole, and travel the length of the throttle body and into the engine. Might be possible though. Put a drop of red loctite on each screw, and tighten them all down with a good bit of force. As long as they all seat flat and are tight, I don't personally see them going anyhwere.
 
Joined
Jan 25, 2008
Messages
1,608
Location
Opelika, AL
Somebody brought up the question of where do you get these O-rings. Aren't they already on there and you just need to move them?

I read the article again and see that you must get these O-rings and they are not already on there.
 
Joined
Feb 9, 2008
Messages
200
Location
Northern CA
The article states to "Be sure that the three small phillips head screws are secure. A drop of loctite is good insurance. Should one (or more) come loose, it/they can be ingested by engine with catastrophic results." I'm not seeing it. How could these screws get inside the engine? The valve would suck them in?

I'm having this problem and it worried me when I first got my cruiser. I posted up and I was told this high idle is normal as you or the article have also stated. It looks simple enough but the thought of loctite and little screws has me a little nervous. I wonder how much a new ISC would cost?

How much? I was at the Toyota dealer looking for O rings to no avail. But, now I know the ISC is about $500.
 
Joined
Jul 12, 2007
Messages
2,105
Location
Gilbert, AZ
Did mine tonight. One o-ring brought the idle down from 1800 rpm to around 1200 rpm. I tried two o-rings but that brought the idle down to around 500 rpm, which I felt was too low. Perhaps a thin washer and an o-ring would get it back to normal.
 
Joined
Nov 28, 2006
Messages
593
Location
Leesport, PA
what year is your 80? And, are you certain you placed the o rings all the way back on the shaft as shown in the picture above?
 
Joined
Mar 17, 2008
Messages
463
Location
Orlando
Website
www.ishamonline.com
the truck is a 1994- and yep i pushed the o-rings up as specified in this thread- drove it today at lunch and sat in the parking lot 5 minutes while it "warmed up"...
 
Joined
Jan 25, 2008
Messages
1,608
Location
Opelika, AL
I have high start up RPMs but my idle is about 500-600 RPMs after engine is hot. Will the O-rings lower my RPMs after the engine is hot too? I hope not.
 

Users who are viewing this thread

Top Bottom