2001 tacoma 4wd idle speed control issue.

removed the throttle body to replace idle control valve. put the new one in and have little change in rpm. starts cold at 1600+, warm at 1400+. 1000 rpm in gear at complete stop. in the old days it would be vacuum leaks. soapy water shows no leaks. 3.4 liter with 300,000 miles. i'm the only driver/owner. check engine scanner calls out idle control system

 

Is there a CEL? Throttle position sensor?

 

there is. seemed to move ok when i had the throttle body off. thanks

 

Id get the cel code and go from there...theres a lot of parts it "could" be

 

went through this with my 99 4runner 5vzfe

old worn TPS does this

get new OEM TPS, reset battery, I bet prob goes away

OEM TPS only, aftermarkets are shitty shitty shitty [I know I got hosed]

 

Just because your getting the PO505 code does not mean it is the Idle Control Valve but the complete circuit .

Poor connection Damaged harness ECM

 

They must have been pretty dumb in the old days. Soapy water detects leaks in a PRESSURE line, not a VACUUM line.
You might still have a vacuum leak. Remove each line and check for cracks, holes, etc.

 

thanks for the advise

 

soapy water will still cause bubbles surrounding the hairline cracks/leaks.

 

That doesn't make sense. I use soapy water quite often to check for leaks in my on-board-air system which are pressure lines.
Wouldn't the bubbles appear in the interior ( where you couldn't see them ) rather than the exterior of the vacuum line?

 

I honestly never really looked into it, nor used it before, it's just one of the processes i heard you can do.

im looking into it right now, it seems youre right. there wont be any bubbles around the vacuum leaking areas.

but! there will be a drastic change in sound when that soapy water actually gets sucked in by the vacuum!

ever hear that sucking sound with water going down a drain? it will sound like that.

im sure that's what the OP was talking about with the water method.

 

my dad and grandfather who have been dead for 40 plus years used soapy water to check for leaks, both pressured and vacuum , still works for me
.

 

but what effect or sign of a vacuum leak do you see when using soapy water?

 

Could just be a worn throttle body... Happened to me

 

I usually use carb cleaner to find vacuum leaks, results in a rpm surge when it gets sucked in.

 

yup

 

change in sound and seeing soap bubbles react to the vacuum leak