That damned burp / 1300RPM constant

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Lug1

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That damned burp / 1300 RPM constant idle

Hi everyone,

I did some work on my Throttle Body and had to remove the coolant hose coming into it.
Ever since putting everything back, I get 1100-1300RPM.

Everything is fastened back well, new IAC gasket, new TB gasket.

I'm suspecting it's air in the cooling system:
Ran the engine with radiator cap off, heater on, squeezed upper rad' hose, some bubbles came up and out, added coolant, for about 8 minutes.

Still, same RPM result.

There was one instance before pulling to the highway where I actually had <1000 RPM while idle, but after pulling into the driveway following that drive and shifting to N - well - same RPM.

More burp needed ? am I missing something else ?
Please help :)
Thank you.
 
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Check all of your vacuum hoses. Make sure they're all tight and without cracks or leaks. Sounds like a vacuum leak.
 
I don't understand how anything with the coolant can cause an idling issue. I've now done the valve cover gasket replacement on two 3rd Gens and know the coolant hose you're referring to under the throttle body. Disconnected that hose on both repairs and lost some coolant each time. No idling problems after reassembly. I've also changed coolant on many vehicles and never had what you're describing.

What exactly did you do with the throttle body? I have read threads that people experienced high idles after cleaning the throttle body. It might be that the IAC isn't closing all the way. Maybe take the air tube off and take another look in there to see if it's moving smooth and not hanging up. I also read people cleared up the high idle problem by disconnecting their battery, letting it sit for 30 minutes, and then reattaching the battery which resets the ECU because for some reason it gets out of whack after cleaning.
 
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wake_rider said:
Check all of your vacuum hoses. Make sure they're all tight and without cracks or leaks. Sounds like a vacuum leak.
Click to expand...

Yes, I went and did that a few times - all hoses are tight. I replaced an intake hose part that was a bit cracked and was sure that was my problem - no go. Other than that - all hoses I can see or touched in the way are in good order.

mtbtim said:
I don't understand how anything with the coolant can cause an idling issue. I've now done the valve cover gasket replacement on two 3rd Gens and know the coolant hose you're referring to under the throttle body. Disconnected that hose on both repairs and lost some coolant each time. No idling problems after reassembly. I've also changed coolant on many vehicles and never had what you're describing.

What exactly did you do with the throttle body? I have read threads that people experienced high idles after cleaning the throttle body. It might be that the IAC isn't closing all the way. Maybe take the air tube off and take another look in there to see if it's moving smooth and not hanging up. I also read people cleared up the high idle problem by disconnecting their battery, letting it sit for 30 minutes, and then reattaching the battery which resets the ECU because for some reason it gets out of whack after cleaning.
Click to expand...

I took the TB off for clean up, cleaned up with TB cleaner. Replaced the IAC gasket and put back well tightened.

About the coolant - I've learned that if there's air trapped in the coolant it might play with high idle, I don't know the exact explanation of how, but again - at the time it made sense.
 
Lug1 said:
Yes, I went and did that a few times - all hoses are tight. I replaced an intake hose part that was a bit cracked and was sure that was my problem - no go. Other than that - all hoses I can see or touched in the way are in good order.



I took the TB off for clean up, cleaned up with TB cleaner. Replaced the IAC gasket and put back well tightened.

About the coolant - I've learned that if there's air trapped in the coolant it might play with high idle, I don't know the exact explanation of how, but again - at the time it made sense.
Click to expand...

Another thought is the throttle positioning sensor is out of whack but that's quite often associated with throwing a code. I would first see if the throttle plate is sticking a little and not closing all the way. If that's not it, it's probably something to do with the IAC.

This looks like an excellent write-up regarding the IAC I found that might help you out.
http://www.toyota-4runner.org/3rd-g...ottle-body-adjustment-including-iac-pics.html
 
when you cleaned the throttle body, did you take the ICV off. I assume you did because you said you put on a new gasket.

when the ICV was off, did you clean it out also, and when you did, well when I did mine, before putting back on the throttle body, I plugged it in, turned the ignition on and off a few times to make it click back and forth, cleaned it again, repeat the on and off
then reassembled everything

vacuum leaks etc are good causes too

and you can have a "Tired TPS" as well. I just did a thread on that, A funky TPS and throwing no codes, but I don't think the TPS is your issue right now
 
I'm going to have another look at vacuum lines.

Edit:
After another look - all lines seem fine.

I'm not sure if I'm starting to imagine things - but the upper intake plenum seems to heat up more than it used to.
Not sure if that means anything. Or it's just due to the higher idle.
 
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Make sure you also check the intake elbow that attaches directly to the throttle body. I had to replace mine due to it cracking from age. I didn't see it until I did a teardown to replace the valve cover gaskets.
 
Since you cleaned the throttle body, had the ICV off and changed gaskets, there is an easy explanation for this, and it is very common to have high idle problems after this type of cleaning.

The throttle body does not have the restrictions it previously had. When you cleaned it, you cleaned out all the grime and dirt that was blocking airflow. So where the computer has learned to set things from numerous other cold starts and hot starts is now out of whack and it needs to relearn these settings.

This process of relearning will take place over the next few hundred miles, but I also think you can force it to relearn by disconnecting the battery for a while like someone else has recommended.
 
88toy4x4 said:
Make sure you also check the intake elbow that attaches directly to the throttle body. I had to replace mine due to it cracking from age. I didn't see it until I did a teardown to replace the valve cover gaskets.
Click to expand...

Yes, I had a torn elbow in the intake hose line, found a good one in a local salvage for $5 (new goes for $50), the deal of the century. :lookout:


Andy in Pa said:
Since you cleaned the throttle body, had the ICV off and changed gaskets, there is an easy explanation for this, and it is very common to have high idle problems after this type of cleaning.

The throttle body does not have the restrictions it previously had. When you cleaned it, you cleaned out all the grime and dirt that was blocking airflow. So where the computer has learned to set things from numerous other cold starts and hot starts is now out of whack and it needs to relearn these settings.

This process of relearning will take place over the next few hundred miles, but I also think you can force it to relearn by disconnecting the battery for a while like someone else has recommended.
Click to expand...

I did think about this. Yes, I had the battery + removed for 40 minutes, but no change has occurred at idle speed.

At this point, I'm driving around. I'm not going to do anything new in there unless I have a new idea.
 
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I guess there are many things which could affect idle speed, but for sure engine temperature will be one of them, perhaps try swapping a sensor if you have a spare.
 
Same type situation happened to me. Replaced IAC mostly fixed then replaced ETC and all the way fixed. Never got a code for either.
 
Unplug the IAC and start. See if idle changes. If it still throws the p0505 it might be the ECU or a wire in between the IAC and ECU.
 
sawguy said:
Unplug the IAC and start. See if idle changes. If it still throws the p0505 it might be the ECU or a wire in between the IAC and ECU.
Click to expand...

I cleared the code for now.

If the code comes back, should I unplug the IAC while the code is on and then start the engine ?
 
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