Car Question

[JLMannin]

Well, actually a minivan question.

I have a 2002 Toyota Sienna minivan with ~130,000 miles on it. Off and on, on an at first very infrequent basis but now much more so, I am having a low idling problem. Usually, this happens on a a restart when the engine is still warm and seems to happen most on cool, damp days. When I start the van, the engine turns over just fine, but instead of idling at the normal speed of a bit under 1000 rpm, it idles very low, say 200 rpm or less. If I give it a little gas, it will stay running - if not, it will die. No idiot lights, and upon restart, it turns over fine but still idles low.

When this problem first started, if I did two foot driving for literally a few hundred feet (say, driving out of a gas station parking lot), it would be idling just fine. On subsequent hot restarts that same day, there was a very good chance this would not happen again. Fast forward to recent - it has done the low idle thing a couple of times on cold starts, and remained idling low for extended periods of time (several minutes).

Other than idling low on an infrequent and and unpredictable basis, there are no other running issues - it runs smooth, no strange noises, no idiot lights, no check engine lights. I have made a service appointment next week to have it looked at, and I thought I would ask this community of experts for their opinions on what the cause may be.

Thanks in advance.

[Gnam]

I know nothing, but found this:


dirty throttle body. you will want to clean the throttle body with a throttle body or carb cleaner with the engine off and the throttle held open,making sure to also clean the idle air control passage.

http://www.auto-facts.org/engine-stalling.html

[Andrew Longman]

I gotta agree with gnam. Sounds like an oxygen sensor or something except that you have no check engine light. Run a few cans of gumout through the tank and spray down the throttle body with some solvent. At least that will rule out gunk as a cause, which at your mileage is a likely cause.

After that the quickest route is to get some computer fault codes, which is easiest done at the dealer. :irked:

[Sean Malone]

In todays cars, poor performance issues can usually be traced to a sensor, (MAP, oxygen etc). One of the dealer scams is that just because your 'check engine' idiot light isn't on doesn't mean that codes aren't being stored. Also, depending on the sophistication of any third party scan tool it may or may not display all of the codes that are available to the dealer. Dealer pulls a code for a sensor, and charges you $800 for a $35 part and you never know.
Your local autopart store will check your codes free of charge but they might not have a decent scanner to read the ones that aren't being shown.
If you are the do it yourselfer, then I'd check codes before taking it in. It saved me $100's of dollars on my truck recently.

[TRDfan]

I have a 00 Sienna with about 115k, but haven't experienced what you are talking about.

I'm guessing Gnam is right on with throttle body needing cleaning. I had mine done about a year ago before leaving the dealership - just to be on the safe side.

I was going to recommend a visit to siennaclub.org - great resource, but it
appears that they are down.

Tundrasolutions.com also has a Sienna forum, might be worth a visit.

Plugs, timing belt done ??

[hickorywoodmark]

Was there a resolution to this problem? I think I have the same one. Did anything suggested here work? Thanks in advance.

[devilmaster]

Was there a resolution to this problem? I think I have the same one. Did anything suggested here work? Thanks in advance.

Welcome to OC hwm, give it a couple days, mannin hasn't been here since the 8th....

[manic mechanic]

Cleaning the throttle body may help, but there could be a deeper problem.

If this system uses an IAC solenoid, it may very well be the culprit. ;)

Trust a pro.

manic

[chop456]

Cleaning the throttle body may help, but there could be a deeper problem.

If this system uses an IAC solenoid, it may very well be the culprit. ;)

Trust a pro.

manic

Seconded. And that's Idle Air Control for those not hip to such things. :gomer:

That stupid part has failed in 2 of my cars. Unlike Chrysler, Mitsubishi was able to locate it in a place that didn't take spider monkey hands to remove/replace.

[JLMannin]

I'll have to check my maintenance records to make sure, but I think it may have been the AIC solenoid.

[gjc2]

It could be a something as simple as a vacuum leak. Listen for a “hissing” sound.

[hickorywoodmark]

JL, Have a chance to check those maintenance records? I took the Sienna to the dealership yesterday, and after an hour of diagnostic work (they didn't want to just try the suggestions I gave them from this thread), they told me the problem is with a catalytic converter (at least with 1 of the 3 converters that apparently exist in the car), but they couldn't tell me which one. They recommend I bring it back for more diag work to narrow it down more. Was told converters run at ~$1500 each.

[JLMannin]

JL, Have a chance to check those maintenance records? I took the Sienna to the dealership yesterday, and after an hour of diagnostic work (they didn't want to just try the suggestions I gave them from this thread), they told me the problem is with a catalytic converter (at least with 1 of the 3 converters that apparently exist in the car), but they couldn't tell me which one. They recommend I bring it back for more diag work to narrow it down more. Was told converters run at ~$1500 each.

The idle fluctuation was due to the idle air control valve sticking, causing the idle to fluctuate. Note that this only happened on warm starts.

Funny you mention the catalytic converter. I just had mine replaced due to P0420, low catalyst effenciency. I had the dealer reset the code. Two months later, It came back on. I took my minivan to a Firestone Autocare near me instead of the Toyota dealer. They replaced the catalytic converter for <$600.

[Methanolandbrats]

The idle fluctuation was due to the idle air control valve sticking, causing the idle to fluctuate. Note that this only happened on warm starts.

Funny you mention the catalytic converter. I just had mine replaced due to P0420, low catalyst effenciency. I had the dealer reset the code. Two months later, It came back on. I took my minivan to a Firestone Autocare near me instead of the Toyota dealer. They replaced the catalytic converter for <$600.

If you don't have vehicle inspections in your area, you can fix the cat with a length of pipe and a BFH. :gomer:

[chop456]

^ That's what I was going to suggest, too. Rebar works well, also. :laugh:

Once all the chunks are blown out, you're good. :thumbup: