Engine idle flip-flop?

I just had the clutch replaced on my 97 3.6 4x4 and when I got it back I started it up and for the first time ever it started quiet, at around 500 rpm idle. I'm used to getting fan blasted at 2000 rpms on cold startup. I thought maybe he tuned it down or something, but after warming up the car I noticed that it was idling in traffic between 1000-1500 rpms.

What is going on here? I talked to him and the only thing he touched topside was the battery that he disconnected. I thought maybe the ECU needed some time to get settled so I drove it around, ran it through about a dozen start/stop cycles, etc. No effect. This morning I had to actually give it gas to get it to start. I've never had issues with the idle valve sticking before, it seems kind of sudden and complete. The new clutch chatters quite a bit, I wonder if something vibrated loose.

Any ideas? I read somewhere that touching the positive and negative terminals together for 20 seconds after disconnecting them from the battery helps 'wipe' the ECU, but I'm hesitant to do this. Is it OK to try?

EDIT: Resetting the ECU didn't do it. I talked to my mechanic and he said the only thing he disconnected that might have to do with the idle were the O2 sensors. Can a bad connection there cause the weird and sudden issues I'm having? It's not throwing any engine lights at me.

 

The intake hoses look kind of worn, and most of them have a few cracks on the ends. Some of them you can twist almost freely on the nipple with little effort, but most are snug. Would it take a large leak to cause conditions like that, or could these loose hoses be the culprit?

 

my mechanic designates that you pay their annual salary !?

Obviously you don't pay him very well, if that's true.


The up/down idle is likely a dirty IAC (idle control valve)
Could be other issues as well...
But it's the right place to start.

If you pay any mechanic the going rate...
they could probably clean that up for you.

Sorry...
I hate when folks refer to someone as being theirs.
that describes someone as solely working for you.

My welder

My mechanic

My landscaper

My bitch

I weld for others... and at a low cost to them.
But the first person I hear that calls me their welder...
Will be looking for a new person to do their welding.

 

LOL. My bad. I meant to say the mechanic whose service I pay money for along with many other men and women! (though I probably shouldn't have). I found one of the tranny mounts mangled and unbolted on the forward end that he neglected to mention, that might account for some the excessive vibrating chatter I've been getting on the new clutch. I can also see some threaded holes along the very front end of the transmission (clutch case?) but have no idea what those could have been for. Is there a protection plate on the front of the transmission housing? I can peek between it and the engine and see the flywheel (I think?) in there. Is that normal?

 

I'll see if I can get to the valve soon. Engine used to have a bit of a whistle that I figured was a small vacuum leak but it went away, and probably not because the leak closed and sealed itself. Is there a chance it could be bad hose connections, or should I really start with that valve?

 

http://www.toyotapartsoverstock.com...key_make=1060&modelYear=2001&ukey_model=15455

 

Man I hope I can get those on without pulling the transmission again. Guy who did it for me claims they were gone already when he pulled it, but that seems unlikely. The little thread holes are a nice shiny brass color. I'm taking it to someone who has a better appreciation for finishing a job correctly on monday.

Just sprayed some carb cleaner on all the hose connections I thought were loose just to get the super-easy stuff out of the way first. No leaks there. Going to check that idle valve now. What's a good solution to clean it? I've got rubbing alcohol, carb cleaner spray, and some electrical cleaner from radioshack.

 

add a coupla' more to your stockpile !? Lol

I've used brake cleaner spray to clean a couple
that were mostly just dirty.
but others that have more carbon build up
will require a longer soaking.

Carbon build up can sometimes be stubborn to remove...
a good soaking, then scraping with a wood dowel helps.

don't scrape using metal scrapers...
scratches on or around the vane will ruin the IAC.

A new replacement is kinda pricey.

looky

https://youtu.be/RgpIg-WkwOY

 

Yup, the valve was completely black and required quite a bit of force to twist. Hosed it with brake cleaner and it loosened right up. Great tip! Thanks a lot for your help.

EDIT: After reassembly it's back to high idle at startup and a lower idle once warm, but overall the idle seems a bit higher than it should be (1100 RPMs at idle once warm, 2000 RPMs when cold). I think I might have rushed it driving and didn't give the ECU enough time to calibrate. I'll unplug the battery for a bit when I get it back from the shop tomorrow and let it idle properly, see if that tones it down.

 

there is a method for testing the IAC in the FSM
to be sure it's rated values meet specification.

Cleaning the IAC may not insure proper function
if the value specs. are below it's requirements.

But I might think to believe, you got a little hurried
when you were cleaning that...
and didn't clean it up well enough.

But I could be wrong...
and it could be the IAC is fubar'd beyond cleaning.

Did you scrape the carbon build-up off...
or simply spray it clean with the brake cleaner ?

Spraying the IAC with brake cleaner may remove the residual grit
and such... and free the vane to rotate more freely...
But if the carbon build-up still exists...
It may still not function as it should.


just sayin'

 

Yeah, IDK. I did get in there with a tooth brush and scraped off what I could. Looked pretty shiny by the time I was done with it. I had to take it straight to the shop to get a transmission mount bolt torched off of the exhaust to get it lined up and bolted on so I haven't had a chance to reset the ECU again.

I'm worried I might have put the little plastic piece in there wrong, but I don't think so. When I tightened the cap down I had it oscillating smoothly between completely open and completely closed. Would adjusting that do me any favors? Maybe set it so that completely open isn't quite completely open (or vise verse)?

This is the first time I've worked with a rotating solenoid. All the ones I've seen in the past were just piston pulling ones with springs to bring it back to default. Can it rotate it both ways? Or does it count on gravity or something to bring it back to default once disengaged?

I'd love a new valve, but I'm fresh out of arms and legs to sell for one.

 

Got it back and drove it a bit and the idle is still hanging out around 1100 on average. The valve feels like it's responsive, it just feels like the overall idle is higher than it should be. Interestingly, when I push the clutch the RPMs drop down to where they should be for about half a second before bouncing back up to 1100. It also cold-starts at around 1100 RPMs now as well, instead of cold starting around 2000 RPMs like it did initially. I feel like the computer should be calibrated enough by now that it has to be another issue.

When I was pulling the valve I saw that the throttle body had a bit of carbon gunk in it and on the butterfly flap so I cleaned them up a bit but didn't spend too much time. I wonder if the gunk was helping to form a seal around the flap and by not getting all of it I left a sliver of space in there. Is a sliver of space in the flap enough to cause +500 rpms and thin starts? What's a good way to eyeball that thing to make sure it's closing all the way? If I put my mouth on it and blow should I get full resistance?

I also wonder if any of the rubber hoses cracked from being pulled off and put back on. Guess I'll hose them down with carb cleaner and if I don't find any leaks I'll yank it back out and try round 2 of cleaning it. I wonder if I have to pull the MAF sensor to clean it, or if I can just spray some electrical cleaner into tube after disconnecting it.

 

Valve was even more gummed up than the first time I took it off. *facepalm*
Spent more time getting all the carbon out, also spritzed the MAF with maf cleaner and tried cleaning the throttle body some more.

I have a ring of light that I can see around the butterfly flap. After fiddling with it a bit I can get it to close all the way if I squeeze down on what looks like a small spring loaded diaphram that connects to a very small vacuum line running over top of the engine. The return spring for the throttle body has about half the force of that diaphram spring, and if I loosen the set screw a little I can get it to close all the way at idle. However, since I don't really know what that diaphragm is or what it's for, I left it where it was for now.

Still getting 1100 RPM idle. What is the purpose of that diaphragm? Can I loosen that set screw so that the butterfly arm doesn't rest on it?

 

EDIT: Pretty sure the high idle was caused by my cleaning the throttle body (kicking myself for that). Return spring wasn't quite closing the butterfly flap all the way without the gunk in there to seal it. If I squeeze it closed just a little bit by hand it idles down right where it should be. Going to try lubing it, and maybe just attach a little 'helper' spring if that doesn't work.

I found this little writeup that helped:
http://www.yotatech.com/f2/throttle-plate-linkage-will-not-close-unless-truck-off-242839/

 

My Sailor.

 

Helper spring worked but the dashpot couldn't keep up with the extra torque, plus I was fighting it on the gas pedal, and was a little worried about breaking it, so I took it off. Put in a new IACV, problem got a little worse.

Finally had the eureka moment this morning and realized that the throttle cable was just too tight (must have been adjusted to a dirty TB). I backed it off until the brackets closed completely, and now it idles perfectly.