Howdy All,
How do I “LOWER” the “High Idle Speed” on my 1998 4Runner with 5VZE engine…???

I recently “ PORTED” the Heads & Intake system on my 1998--5VZE engine.
I cleaned up the entire Intake system all the way from the Valves Ports back to the Throttle Body; removing all the Casting Flash and B/S left behind by Toyota.




I re-assembled everything today and the engine “FIRED_UP” ~~~>>> right off…everything is Golden except for a "High Idle Issue."

Before I started all this, my 1998 4Runner always had a “High Idle.”
When it was COLD the engine would race up to 1,500 RPM, then drop down to 900 RPM after it warmed up. I always tossed it into gear as soon as it fired up. It has an automatic transmission.

NOW…today…after getting the Top End back together…it fires up fine, drives clean and strong…BUT now it races up to “2,000 RPM when COLD” and drops down to 1,500 after it warms up…!!!

I’ve check to insure all my throttle control cables are adjusted correctly.
I can see the throttle Butterfly Shaft is closing all the way.
I Backed-Off what looks like an Idle Adjuster Set Screw with Locking Nut.

Nothing is helping to “LOWER” the High Idle Speed
Can anyone shed any light on my High Idle Issue…???
Many Thanks,
Rex M...

I recently did a road trip with this 4Runner burning up over 1,000 miles.
The truck runs great…giving me 80 miles per hour @ 2,500 rpm all day long.

 

After thinking about my engine last night I plan to head out to my work shop and check for Vacuum Leaks...
I have "NO" Engine Light issues so the ECU seems to be happy.
I'm hoping I have a leaky gasket some where.
I attempted to add some pictures but I never seem able to get them top post...???
I'll keep trying...to learn this site better...thanks

 

Well if you had the engine apart... and if you diconnected the Battery for an extended period of time the computer is now having to go through a drive cycle to re-learn the engine. It prob does have a vacuum leak some where trace it down before the truck completes its drive cycle and throws the MIL back on. Depending on the Vechile a drive cycle can take anywhere from 2 hours-2 weeks-a month. Since you said you have a "work shop" look around and see if theres a vac leak and or check various sensors and acctuators like tps,Iac,ect.

 

Have you tried cleaning your IAC valve? It is located on the bottom of the throttle body. I had some of the very same issues that you are describing after cleaning my own throttle body and intake. Cleaning the IAC remedied those gremlins.

 

Many Thanks...
My workshop is a converted "Horse Barn"...I'm not a high tech wrench, just learning as I go. I've done seven rebuilds in the last year with all 7 still running fine so far. I enjoy working on the rigs. I will dig into the IAC after reading up on this valve.
Again...THANK YOU for taking the time to reply to my problem(s)
Rex M

 

No problem. I wish I had a barn to work in! Right now it's either the apt. parking lot or drive 2 hours back home to the garage. Yay college! haha
Also, here is the link to a great write-up I used when cleaning my IAC. Hope it helps!https://www.yotatech.com/forums/f123/re-3-4l...ac-pics-92286/

 

I hear ya man...I went back to school a few years back and it was a hassle but well worth it in the long run.

I went out and checked my engine for vacuum leaks and found a major one!

My goal was to “Port” the Heads and clean up the air intake passageways. I picked up a Basket Motor for $100, which gave me all the extra parts I needed. (I also rebuilt the Bottom End of the Basket Motor with new Bearing & Rings. I plan to use this Short Block for my “Supercharger Motor” when I get the $$$ bucks up.)

After cleaning up the spare Air Intake Chamber Assembly and bolting it onto my 5VZE motor still sitting in the 4Runner I noticed an 1/8 vacuum nipples coming out of the Air Chamber which had a short section of rubber hose with a Tee splitter in the end. My original motor air chamber did NOT have this Tee splitter. It was getting late and I was getting tired…I didn’t think anything about it and failed to plug off the unused side of the Tee. This left me with a full 1/8-inch open “vacuum leak” which messed up my Low Speed Idle… Big-Time…!!!

After removing the Tee and running a new vacuum hose my am happy to say my engine is running GREAT with a nice, smooth, “Low Idle.”
Problem Solved…!
HAPPY TRAILS & THANKS
Rex M.

PS: I'm still having problems Posting Pictures to this web site...can you help me with that or tell me where to go to read up on Posting Pictures. I tried "Resizing the Pictures before posting them but they still are not coming throught...???
Best of Luck with the classes~~~>>> Stay Strong...!!!
Picture test #3:
C:\Documents and Settings\Owner\Desktop\3.4 Engine #3 Rebuild\3.4 Porting Pics
this is a picture of the 1/8 hose I took of the orginal motor

 

Picture test #4

 

You can use the "attachments" button (little paper clip) to make thumbnails like the one I have here or you are going to have to use photobucket or another photo sharing site to get an html address to put into the "insert image" button. And make sure your image is small enough to fit

 

Glad to hear you found the solution!