Idle Speed Air control Valve-BAD...I think

[jasonvibe]

3 mos. ago.I did a complete cleaning of this as described here and the Matrix OC site. I also lubed the end bearings as these should not be left "dry" after the cleaning. The shaft spun freely. Plus I replaced the o-ring and gasket. My idle was very good 720rpm no load. But 30 days later I had to readjust it on the black part. This I believe is simply an electromagnet. FYI-Turning it clockwise increases idle. Now again this week the idle was low and NOW the adjustment is "maxxed out". it's idling 700rpm no load. That's alll I can get. But 3 mos. ago I could get it to 1000rpm if I wanted...but spec. is 650-750. 750 is the best I had found for smoothness no load which results in ~700 in gear. I suspect the electromagnet has started going bad.I do see the whole assy. avbailable for $200 @ AdvanceAuto. FYI- I also did an OBDC "scan" w/my very good scan tool(tells me everything) and found nothing "out of spec". Lastly- the intake gaskets were replaced last year along w/checking valve clearances. It takes the gas instantly - no hesitation. So intake leaks from these are not the issue.Anyone else have their ISAC being electrically bad?

[jasonvibe]

WELL, i finally replaced the ISAC valve(idle speed air control). 1st one they sold me was bad...2 weeks after install it idled worse than ever. Yes, I disconnected the battery to reset the engine computer. UGH!. The second one is now slightly better than my original in some ways. I did notice that if the air is high in humidity aka raining, the car idles perfect no matter what I set the inside fan speed at. FYI- the higher the fan speed the worse my car would idle. I am wondering if the MAF sensor is slowly going bad and not seeing correct air flow. YES, I cleaned the MAF sensor as described on the wonderful sight. Anyone with ideas or experiences like mine.

[star_deceiver]

It almost sounds like something electrical is quite corroded and the high humidity/moisture bridges the gap and cleans up the connection. You may want to check your battery terminals, grounds, alternator connections, fuses, MAF connector, ect. A bad fuel pump, breather system could also be acting up.

[jasonvibe]

It almost sounds like something electrical is quite corroded and the high humidity/moisture bridges the gap and cleans up the connection. You may want to check your battery terminals, grounds, alternator connections, fuses, MAF connector, ect. A bad fuel pump, breather system could also be acting up.

I have been having this low rough idle problem close to a year+ now. It's especially bad when the heater fan is on.I even replaced the fan after the "resistor" burned out the 2nd time. All you list has been checked inclufding the fuel pump pressure. I have also put in a new battery. I am an electronic tech. I know how moisture can affect voltages, etc. I will say I have not checked every ground connection in the engine bay. That is a simple thing I will do too. Thanks

[plausipo]

Anyone with ideas or experiences like mine.

I have the same rough idling problem with 04 base. During idling, it seems like the car is trying to go as low RPM as possible (down to 5xx RPM) and then realized that it's going too low and rev up again (up to 7xx). The cycle continues (I used an OBDII with an Android app on phone to monitor). I did clean MAF, valve in throttle body, change spark plugs, with no avail.

[plausipo]

Found something here: Bad Intake Manifold Gasket - compromising vacuum
The problem "During idling, it seems like the car is trying to go as low RPM as possible (down to 5xx RPM) and then realized that it's going too low and rev up again (up to 7xx). The cycle continues"
The Possible Fix: http://matrixowners.com/index.php?/topi ... p__1254417
#1: It's not its thickness that's a problem. It's what it's made out of. It cracks and contracts in cold weather, and stops sealing properly.
#2: It's like $11.
#3: It's easy peasy to replace. But don't listen to that TSB. the TSB wants you to drain the coolant first. You'd have to be on drugs. Just disconnect the T/B and move it aside. No need to open the cooling system at all.
Full instruction here: (remember to clear the fuel trim values by disconnecting battery (–) for 90 second after these procedures)
http://www.toyotanation.com/forum/132-9 ... ost3829971

[jasonvibe]

in my oroginal post . I did replace the intake gasket. Yes the new orange o-ring gasket is better than the BLACK type. I have since posted other possibilities that I I am checking out. Well, the past year I did buy an ISAC valve. Which only help me slightly. Simply....wasted my $$ as I cannot return it. This better describes what's happening. The issue I am having I should have described as a decreasing idle with a significant lag getting to idle when coming to a stop. new OR old ISACV it's the same , I have cleaned the MAF and suspect this could be "weak". As in humid weather...aka dense, water logged airr air the car idles much better...like new. BUT NOW I REALIZE... it's when I drive it at night and the lights "kick" the idle up some. Yes, the ECU compensates for electrical load....somewhat

[plausipo]

in my oroginal post . I did replace the intake gasket. ...

Yes sir, noticed it afterwards. I changed intake manifold gasket (not really worn after ~140,000km, 1ZZFE year 04), cleaned throttle body before and after valve, MAF and disconnect battery (>2 min) today... nope, doesn't resolve my rough idling either (stop, gear in D, foot brake on). Did "feel" the car run smoother, and RPM goes low as 6xx not 5xx. Also one thing I noticed, after the plastic manifold where the air goes in, the metal "manifold" is really dirty and full of oil. Any concern in there? Makes me wonder, why cleaned the parts in front if the air has to arrived into that dirty compartment before mixing in with fuel? Another strange thing is, the car does not ever need oil refill (I do change oil 2x a year). Maybe next time I shall change PCV and really try to clean inside the metal manifold. See if I can find any cleaning instruction before doing that.

[jasonvibe]

metal manifold...I think you mean the throttle body. The PCV I was also consideing. FYI- this can be tested. It's a oneway valve allowing vacuum only into the manifold. It's on the cam cover towards the firewall. Removing the hose and putting pressure on it should show whether it's "leaking". But mechanics have told me it's not likely to be the issue because it 's suppose to be open as long as the engine is running. Basically it's a pressure relief valve for crankcase pressure helped by the intake vacuum. But if it's stuck closed...then you'd have a problem. I put a vacuum tester on mine...no problem. Or you can put a clean hose on and "suck"...it should be easy.

[plausipo]

metal manifold..

Oily and black inside

[jasonvibe]

oh...THAT's THE ACTUAL INTAKE valve area.AKA the head. All cars have this OIL issue. Which is caused by the car's PCV systems...it's normal...to a degree. Yes brown oilyness. Or simply brownish. typicaly nothing to worry about. Can be cleaned w/laquer thinner or brake cleaner. The idle is supose to be 650-750. Should not be lower than 650...even in "D" I have a PC program to connect to the OBD port to watch this. Lowest mine goes approx 620 ~ 625...that's about where the "vibes" start. hah..vibes. It happens when the car is supposedly fully warmed up. But I think the oil is still cold and it takes another 10 mins of driving for this to be better. But in hot weather it does it too. Even after warmed up. Or having the fan on high in "D". I've had the car since new. I know this is not correct. I did many things. Such as check the "valves" clearances. Most people do not do this. It's in the owners manual @60k. I checked mine @70k miles. All were @ clearance center of specifications. Something that should not be skipped.

[plausipo]

1) cleaned MAF 2) Cleaned Throttle body 3) Replaced manifold gasket 4) Replaced spark plugs 5) Checked vacuum leak around manifold and TB 6) Checked hose 7) Added 1/2 bottle STP each in 2 consecutive fill-up trying to clean up fuel line ... NO CHANGE!
8) Replaced PCV valve, without resetting ECU, the car idles much rougher than before for the first day, then return to "normal"

Seems nothing more I can do except those that you'd already done.

Now I just shift to "N" while waiting for the red light to turn. Peace and quiet.
You can't change the world (no, not even your own car), but you can change yourself.

[jasonvibe]

I did all of what you did except the PCV replacement. But I made sure all the hoses ends were clamped w/better clamps. The PCV one is a joke. This leaves the power brake hose and emissions hose next to the throttle body. So, I put a new clamp on the power brake hose. NOW, I am going to cap the emissions hose fitting at the manifold. If the car runs better...then the "vacuum valve solenoid" near the strut tower or something in the emissions system is leaking vacuum going. This connects to the charcoal canister under the fuel tank Note: this "valve soleniod" does not operate all the time. At least that's what I think. But on hot days I think it does to equalize the pressure in the fuel tank. Manifold gasket. Did you get the Toyota orange one ? Also I have learned the idle cannot be changed manually by a mechanic with simple tools. As the ECU makes the final idle.."as best as it can". Lastly, mine idles best in rainy weather. OR when the headlights are on at night. The ECU must kick up the idle w/lights on. Could my MAF be weak and does not notice proper air flow till the humidity is high? Since most stores do not take returns on electronic items. Wish I could do a swap test with someone. LASTLY FOR YOU.. DID you clean the ISAC valve(idle valve)??? It's the bearings that do get sticky sometimes, along with "carbon" build up from the PCV valve design. The valve should be removed for best cleaning w/brake cleaner or carb cleaner and the bearings oiled w/synthetic oil.