Iac and low rpm problem - Toyota Nation Forum : Toyota Car and Truck Forums

Crlnd132 · 05-05-2011, 08:58 PM

hi. I have a low idle problem on my 5sfe. On cold start it idles at 300rpm, warm it idles at 200rpm. Removed iac and cleaned. It seems like the rotor can move freely, cant tell for sure but it seems to fully open. Reinstalled it but no change.
If i disconnect the iac socket, rpm does drop a little more. Weird thing is that if i remove the iac motor and move the rotor by hand with the engine running, rpms just climb to 700 which is still low.
Ect is oem new btw.
Also, throttle cable and kickdown cable nuts are set at the middle. I dnt know if thats the factory setup.
If iac is not the problem, what can be causing the low idle?

***fenixus*** · 05-05-2011, 09:22 PM

set the throttle cable and kick down cable so the line stopper is hidden (0mm clearance). if stopper sticks out then it's not good.

you may need to tighten the throttle cable a bit, nuts on my 5s-fe are more towards the driver side than in middle (factory setting was like that) though, tighter is towards passenger side however, so maybe your problem is somewhere else...

was the throttle plate adjustment screw ever messed with?

Crlnd132 · 05-05-2011, 10:09 PM

Couldnt tell. Bought it used. Does the throttle plate has to be fully closed at idle? I think i saw it fully closed.

***fenixus*** · 05-05-2011, 10:30 PM

yes.

***JohnGD*** · 05-05-2011, 10:40 PM

Quote:

Originally Posted by Crlnd132

Couldnt tell. Bought it used. Does the throttle plate has to be fully closed at idle? I think i saw it fully closed.

***JohnGD*** · 05-05-2011, 10:41 PM

Throttle plate should be fully closed at idle. So I think the IAC needs to be checked again.

See if the motor turns if you jumper battery voltage. Just don't jumper the wrong terminals. There may be a DIY on this test. The best way to clean the IAC is to disassemble the motor and the thermostat sides.

Did you do this:
5sfe IAC Removal (lots of pictures)

The rotor should spin freely like a top. And under the flat thermostat cover you can leave out the plastic cup that forces cold air idle up. If the previous owner messed with the thermostat spring and you leave the cup in there that could be a reason of forced low idle. So just bypass it.

Quote:

Originally Posted by Crlnd132

Couldnt tell. Bought it used. Does the throttle plate has to be fully closed at idle? I think i saw it fully closed.

Crlnd132 · 05-06-2011, 08:37 AM

Thanks. Ill dissasemble the iac again, remove the cup and energize the iac directly and let u know the results.
Right now im getting the 200rpms at idle. If it returns to the normal values, will it mess with mpg?

***fenixus*** · 05-06-2011, 01:32 PM

just a quick question ... does your engine actually run when idling at 200-300rpm or it dies when reaching that speed?

Crlnd132 · 05-06-2011, 05:46 PM

it actually runs at 200rpms. hasnt died since i have that problem. on a/c on, it almost reaches 0rpms at N or drive and the engine oil light begins to blink but never dies.

Crlnd132 · 05-06-2011, 06:07 PM

ok updates!
1. removed plastic cup from inside IAC and same horrid idle.
2. removed IAC connector and with engine off energized the IAC directly and sounds like it works
3. with engine on, energized directly IAC and idle climbs from almost 0 to 300.

Then i removed TPS connector and idle climbed to 750 in neutral. 450 in drive.

is TPS whats causing the low idle? can someone explain me what if the tps for? i drove a few miles with the tps disconnected and i dont feel any strange thing.

***fenixus*** · 05-06-2011, 06:15 PM

I think you've got it. the TPS could cause it very well!

Throttle Position Sensor, it tells the ECU the angle/position of the throttle plate. weird things can happen with this sensor bad.

Crlnd132 · 05-06-2011, 06:26 PM

thank you! can the tps be serviced, cleaned, adjusted?
can i live without the tps connected?

***fenixus*** · 05-06-2011, 06:40 PM

TPS affects gear shift points while driving, I wouldn't just leave it disconnected, it may render the car non-drivable or be dangerous on road.

you can try doing some cleaning on it, but I believe the problem is with worn out contact points in it, you may need a new one from dealer (cheapest online, .e.g. from TOYOPARTSMAN).

alternatively you could try a used junk yard sensor, it should do as well, but won't be perfect (because it's used and some wear and tear will be present).

I'm surprised your problem did not trigger TPS sensor or range CEL, e.g. P0120 or P0121

Crlnd132 · 05-06-2011, 08:24 PM

no CEL at all. ill reconnect it till i have the time to buy a new one.
thanks a lot for the help

***fenixus*** · 05-06-2011, 08:32 PM

no problem, good luck!

I have just noticed you are in Equador, and not in USA

likely getting it from dealer will be only option, unless you have access to cheap used parts from some junk yards, might be worth it to check if it solves/improves the trouble this way and then get a brand new one from dealer when needed.

this is the part part number:
89452-33010 Throttle Position Sensor for EFI
$140 MSRP