Any help that can be provided is greatly appreciated!

Here are the details:

05 scion XB auto trans. with AEM aftermarket intake system

Was experiencing problems with car shifting at correct times - replaced transmission vehicle speed sensor, which corrected the problem of shifting. At the same time since everything was 1/2 apart, removed the throttle body since it was all gunked up and cleaned everything off. Since then, the car has has a high idle problem that won't go away (idles between 1,200-2000 rpm in park/neutral, about 1,000 in gear, and sparaticly high when driving). Also, the car is due for emissions and has a check enging light, so it won't pass - it is a P0505 (problem with idle system).

I have tried numerous things to try and correct the problem - replaced idle air control valve, PCV valve, throttle position sensor, looked for vac leaks, checked wiring, you name it. I'm down to my last two ideas which are to install a new throttle body gasket (incase the old one is causing a leak somewhere I can't see), and then finally try a new MAF (which I was trying to avoid due to the cost). I'm hesitant to believe the MAF would cause high idle - I'd think it would be more rough or poor idle if there was a MAF problem.

I've been trying to find out as much info, as I can, but keep coming to dead ends. I came across some vague information about recalibrating the throttle position sensor when removed & installed (does this seem accurate or right), but didn't see any way to do that. Also was wondering - the trans speed sensor was a different part number than orig- could that affect idle (I am doubtful though, as the car is shifting fine at all other times while driving). Could it be that everything is OK, but it is the computer, or it needs to be flashed by the dealer?

Again, I'm coming to the end of the road with what options I have left & any input of past experiences would be greatly appreciated! Really trying to not have to go to the dealer so I don't drop a ton of $.

Thanks!!

 

That definitely sounds like a vacuum leak and since you messed with the throttle body that's probably where it's at. Those gaskets tend to not like being reused...buy a can of carburetor cleaner or starter fluid and spray it around where the throttle body mates to the intake manifold and see if it messes with the idle. If it does then you've got a leak.

Regards,
-Duo

 

I have a scion xb 2005 automatic (110,000 miles).

Recently I have often noticed that after driving a while, the idle speed is way too high - around 2000. I usually notice this at a traffic light - the car tries to pull me forward. i have also noticed that this more likely happens in cold weather (which happens a lot here for half the year, as I am in Canada).

If I put the car in Park, when i notice this issue, the RPM is about 2000-2400. Normally at startup the RPM is about 800.

I have also noticed that if i hit the accelerator pedal when this happens, it usually reverts to a lower RPM - but not always. Yesterday after doing that it decided to idle at 4000! I had to shut off the car and restart it.

I recently had a master mechanic replace the throttle pressure sensor, but it had no effect.

My only mod is a remote starter that was on the car when i bought it second hand.

Since my symptoms are similar to yours I thought I'd post and see if you ever found a resolution to your problem.

Thanks

 

Just a few ideas.
Do you have a carpet under your feet that is pushing the throttle pedal down?? Toss carpet
Is the throttle cable sticking sporadically and holding the throttle plate open?? Lubricate or replace cable
Does the throttle plate move cleanly when you press on the cable under the hood and go all the way back to the throttle stop?? Throttle body may need to be cleaned.
Might be corroded electrical connectors?? Disconnect, spray with WD40 and reconnect a few times.

 

Rich alluded to something, "engine ONLY idles at speed allowed by intake air!" Pure physics, in order to rev at any engine speed, you need X-amount of power generated to spin it that fast. More power requires more air (and matching amount of petrol).

So... find where that extra air is going in. Especially common when intake is taken apart and put back together. ALWAYS replace old gaskets with new ones. Pay attention to locating dowels and don't get parts angled and hung up on dowels. Always tighten bolts incrementally in criss-cross fashion, etc. etc.

 

I know this is old but did you ever figure out the problem?