96 SC, Idles high when engine is operating temp.

[Thane]

When the weather is cold, the engine idles high always.
I read an article on the net. where black flakes can clog the
pasage to the throttle body.
Has anyone experienced this problem and fixed it?
Thane

[95-le/sc-all-trac]

I've experienced and am still experiencing the high idle problem,i tried popping the radiator drain twice to see if it would help it,but didn't really,i'm going to have to get the time and money to afford having it flushed completely and see if it helps any

[timsrv]

I've read a few posts here from people that had that same problem. In most cases draining, flushing, and replacing coolant cured it. Seems odd, but that's what they said. I've never experienced this problem in any of my Previas, so this is only second hand info. I always drain, flush, and replace coolant every 2 years anyhow, so maybe that has kept the idle speed gremlins away from mine. Tim

[Thane]

Tim
Is there a product on the market that you use to flush/dissolve any
contamination that may have accumulated within the throttle body.
If not, maybe someone has a home remedy that has worked for them.
Also I'm trying to establish if there is a link between the coolant sensor
on the throttle body and proper function of the egr valve.
Thane

[95-le/sc-all-trac]

I've read a few posts here from people that had that same problem. In most cases draining, flushing, and replacing coolant cured it. Seems odd, but that's what they said. I've never experienced this problem in any of my Previas, so this is only second hand info. I always drain, flush, and replace coolant every 2 years anyhow, so maybe that has kept the idle speed gremlins away from mine. Tim

the problem presents itself in supercharged previa's only from what i've heard,i was told on the naturally aspirated previa's some do high idle,but it's usually the throttle positioning sensor,it's already been replaced on my supercharged

[95previa]

Mine also suffers from this problem but it hasn't bothered me enough that I am motivated to do something about it. Besides, I need a reason to look forward to spring!

More info on yahoo previa board.

http://autos.groups.yahoo.com/group/previa/files/Black%20Flakes%20-%20High%20Idle

[95-le/sc-all-trac]

well i've decided to try and fix it tommorrow,so i'll let you know how it comes out,it's way to cold outside and dark now to even think about doing it

[Thane]

Well, I was going to start looking into it but now my heater fan quit
working. It doesn't even work on high and normaly when the resister
goes, you still have high range.
I can't believe this... first there was engine check light on in which case
I found out the egr or the ecm may be involved in that. Then when it got
cold out it started to idle high and now the darn heater fan quit.
Tomorow I'm going to fire up my old 89 pick-up (yes, it's a toyota) and
take it to work until I solve some of these egg problems.

Thane

[95previa]

Doesn't work on high...that's not good. The brushes might be gone. I have heard the brushes can be replaced for cheap, but haven't done it myself. I just ordered a resistor for my 89 p/u today .

[timsrv]

As far as the heater motor goes, open your hood and give the black air scoop a good bang with your fist (hit it near the top where it goes into the air box). If it starts running, then your motor brushes are worn out. You can usually get it to limp along by doing this for a few thousand more miles til you get a chance to change it out.

Also your high idle problems may be related to the Idle Speed Control Valve. You can check the the electrical portion of the ISC valve with an ohm meter. When you unplug the connector, you will see 3 terminals inside. Measure the resistance between the center post and the other 2 posts. You should see 18.8 - 22.8 ohms in both locations. If the resistance is not within this range, it is bad--Replace it.

If you haven't flushed coolant in the last couple years, now would be a good time to do it and it may help. I never use any kind of chemical products to flush, I just hook a garden hose up to a flushing kit tee, open the radiator drain valve, then adjust fresh water flow to match drain rate. Once I get the reservoir to maintain a constant level, I let it run for about 20 min or so. Then it's just drain and refill with new antifreeze. Here's a picture of where I put my tee. Tim

PS: All my Previas are naturally aspirated, so I may be way off base for those of you with supercharged versions. Tim

[timsrv]

Oh, just thought I'd mention it's nice to see a lively discussion in the Previa section. Up til now it's usually pretty dead here. Tim

[Thane]

Tim
You didn't mention it but while flushing the coolant system the engine
needs to be running to circulate through the engine completely, is
this correct?
Also, where did you get the tee junction that you installed?

Thane

[timsrv]

Oh yeah, engine running. You can get those flush kit tees a lot of places, but I think I got mine at Napa. Tim

[Thane]

Thanks Tim
I'm going to do this right after I get my heater fan running so I can
defrost my windsheild.

Thane