4age high engine idle

[ssspacely]

In my case one of the lines didn't quite seem to be getting hot. I would have assumed the iacv itself was clogged if it wasn't brand new. Then I got to thinking... not much coolant came out when I disconnected the lines to swap iacv's. Normally those lines should flow a lot of coolant if disconnected. On that engine I just ended up installing an iacv delete plate since I didn't feel like trying to clear the lines. That fixed my idle issues... aside from cold starts...

Very interesting. If I remember correctly, when I disconnected the lines from the IACV there was not a lot of fluid either. Things are making some sense. I have an IR thermometer somewhere. That is also a good test.

[ssspacely]

I capped the port from the IACV on the inside of throttle body and the idle came down to normal.

While this ^^^^ test appears to accurately pinpoint the source of your high idle, it is necessary
to clarify a few things before going further down this line of diagnosis....

1. When the engine is warmed up and the ISCV port is blocked, the engine idles @ what rpm ??
2. When the engine is cold and the ISCV port is blocked, will the engine start ??
3. If the cold engine starts with the port blocked, it idles @ what rpm ??
4. If the cold engine starts and idles, as it warms up the rpm rises to what rpm ??
5. Does the idle speed ever drop down as the engine is warming up ??
6. Does the idle speed change when the A/C clicks ON ??
7. Does the idle speed change when you turn the lights ON or step on the brakes ??
8. Have you checked the ignition timing with the ISCV port blocked (diagnostic port not jumped) ??

Contrary to popular opinion, there are no evil demons inside your engine that play tricks on you.
Idle speed is essentially controlled by the amount of air that gets into the engine, ignition timing
and temperature. There are of course many different things that can mess with your idle, but if
your statement quoted above is accurate, you have eliminated 95% of them.

Cheers... jondee86

Ok all. I finally had time to mess with the car today. I did a lot of the tests that jondee asked but couldn't answer before. So I tried to start the engine with the IACV port blocked and the engine cold. It really didn't want to start and it was about 50 degrees outside. I had to hold the throttle open a little. I also played with the idle screw. Eventually i got it to idle at around 800rpm.

When the engine warmed up thoroughly, the idle increased by about 300rpms to around 1100rpm. I had to adjust the idle screw again to get it back to 800rpm. I let the engine idle for a good 30 to 40 minutes as I checked the timing. The timing was off and I tried to adjust. I don't think it is timed properly but I will come back to that.

With the engine thoroughly warm, I touched all of the hoses in the cooling system. The hoses to the iacv were not very hot. The 2 inch radiator hose on the top of the radiator was good and hot and the radiator itself was hot. The bottom hose to the radiator was not so hot either. ThoUgh I would imagine that after idling for that amount of time the lower rad hose would be hot. I am questioning the thermostat or if there is some gunk plugging the system and reducing coolant flow. The engine never overheats but why would those hoses be cold? I pulled the two hoses off of the iacv and found that rad fluid would drain from one but not the other. The one towards the front of the car would drain fluid easily but the hose on the back of the iacv would not drain well. Good indication of a plug in the line somewhere?

After doing all the tests I pulled the plug blocking the iacv port in the throttle body. I started the car and the engine idle jumped from 800 to around 2500rpm. So.... Low flow to the brand new iacv? Plugged with gunk? The thermostat is new by the way.

So I also tried to set ignition timing. Never actually done that before. It seemed to be way off. I adjusted it to the 10 deg BTDC with the plug shorted in diagnostic mode. I was able to plug the port and get the idle to 800rpm and try to set timing. With the service plug shorted to diagnostic mode, i also noticed the error code 11 blinking. This error code is either the "ac switch on or the idle switch off" according to the FSM. The ac switch was in fact off so it must be the idle switch on. Does this idle switch correspond to the idle switch that yoshi was talking about in his other posts? Does this mean I now have to adjust the TPS?

So I know it has to do with the iacv. The timing and the TPS. Any tips on how to adjust the TPS? I have a FSM and read the section on how to do that but I didn't quite follow.

Thanks everyone for your help. It's encouraging that I might actually get this thing fixed.

[jondee86]

4AGE 16V - How to adjust the TPS - DIY by Matrix Garage

Cheers... jondee86

[ssspacely]

Ok. Flushing the cooling system. I can get water to flow through the IACV hose connection toward the front of the car but I can't get fluid to run through the hose connection towards the rear of the car. I took out the thermostat and still no flow.

So should I get easy flow through here? Does this mean it's plugged or is the water pump preventing flow through that hose connection. I feel like I'm so close.

[ssspacely]

Has anyone seen a clogged heater core or the cabin temperature valve cause a high idle? I am at a loss.

[ssspacely]

Definitely no flow of coolant through the iacv. I checked the hoses that run a cross the engine beneathe the intake manifold. They were clear. I can get flow through one of them pipes leading to the iacv using a garden hose but the other pipe does not flow easily. I have not been able to check the hoses behind the engine near the firewall. Hard to get to. Frustrating to say the least

[yoshimitsuspeed]

At least you found the problem. Just gotta find the cause. Start digging in hehe.

[ssspacely]

At least you found the problem. Just gotta find the cause. Start digging in hehe.

Found a smoking gun. After digging further I found an old post from Jondee with this picture

The out 2 is called the cylinder head rear plate. I took it off and found that mine has two vaccum actuated valves. One is broke as you can see here.

The vacuum line was then looped like this [img]http://images.tapatalk-cdn.com/15/04/21/0c4bb0bce20bbc3b5dd04c20bd29cb55.jpg[/img]

Looks like the only thing it can be. I ordered the part and waiting for delivery. Very excited to possibly have the car run normally. Can someone explain what those vacuum valves do? How they work? Thanks for the help.

[yoshimitsuspeed]

Those only switch vacuum on and off to things like the charcoal cannister. Can't think of what a second one would be for but you should be able to find details in the FSM.
They wouldn't block flow to anything.

[ssspacely]

Those only switch vacuum on and off to things like the charcoal cannister. Can't think of what a second one would be for but you should be able to find details in the FSM.
They wouldn't block flow to anything.

That's what I thought. The valves don't actually control coolant flow.

So you don't think it would affect the idle? I have checked all the coolant lines and nothing is blocked. Could something be blocked in the head not allowing flow of of the back of the head. The out 2 in the diagram

I was really hoping the broken vacuum switch was the issue.

[yoshimitsuspeed]

If the coolant was bled very well to begin with and if coolant was flowing properly through the rest of the system then a blockage somewhere would be my guess. I would tend to suspect much more likely in one of the lines outside the motor. If anything was blocked in the motor (which is less likely to begin with) the motor would not flow well and would have likely overheated.
I would expect the blockage to be somewhere in that throttlebody coolant circuit. It's very likely the blockage could be in the IACV it's self as there will be some sharp turns and restrictions in there.

[ssspacely]

If the coolant was bled very well to begin with and if coolant was flowing properly through the rest of the system then a blockage somewhere would be my guess. I would tend to suspect much more likely in one of the lines outside the motor. If anything was blocked in the motor (which is less likely to begin with) the motor would not flow well and would have likely overheated.
I would expect the blockage to be somewhere in that throttlebody coolant circuit. It's very likely the blockage could be in the IACV it's self as there will be some sharp turns and restrictions in there.

Brand new IACV and I pulled all of the coolant lines to check for a blockage. Nothing was blocking the coolant lines. The heater core blows hot air so I assume there was good flow through there.

I am stumped. The only thing I found was that broken vacuum valve.

[yoshimitsuspeed]

If the coolant was bled very well to begin with and if coolant was flowing properly through the rest of the system then a blockage somewhere would be my guess. I would tend to suspect much more likely in one of the lines outside the motor. If anything was blocked in the motor (which is less likely to begin with) the motor would not flow well and would have likely overheated.
I would expect the blockage to be somewhere in that throttlebody coolant circuit. It's very likely the blockage could be in the IACV it's self as there will be some sharp turns and restrictions in there.

Brand new IACV and I pulled all of the coolant lines to check for a blockage. Nothing was blocking the coolant lines. The heater core blows hot air so I assume there was good flow through there.

I am stumped. The only thing I found was that broken vacuum valve.

I would bolt everything back up and hook everything back up except one of the hoses on the IACV.
Then take a garden hose and stick it in the fill neck and blast it with water. Watch the disconnected line at the IACV and make sure both the IACV and the unhooked hose both have good flow out of them.
If they don't both have good flow I would try to figure out why not. At least that should point you in the right direction of which end of the line is restricted.
If it does have good flow I would hook it all back up and bleed the system really well and try again.

[ssspacely]

If the coolant was bled very well to begin with and if coolant was flowing properly through the rest of the system then a blockage somewhere would be my guess. I would tend to suspect much more likely in one of the lines outside the motor. If anything was blocked in the motor (which is less likely to begin with) the motor would not flow well and would have likely overheated.
I would expect the blockage to be somewhere in that throttlebody coolant circuit. It's very likely the blockage could be in the IACV it's self as there will be some sharp turns and restrictions in there.

Brand new IACV and I pulled all of the coolant lines to check for a blockage. Nothing was blocking the coolant lines. The heater core blows hot air so I assume there was good flow through there.

I am stumped. The only thing I found was that broken vacuum valve.

I would bolt everything back up and hook everything back up except one of the hoses on the IACV.
Then take a garden hose and stick it in the fill neck and blast it with water. Watch the disconnected line at the IACV and make sure both the IACV and the unhooked hose both have good flow out of them.
If they don't both have good flow I would try to figure out why not. At least that should point you in the right direction of which end of the line is restricted.
If it does have good flow I would hook it all back up and bleed the system really well and try again.

You mean stick the garden hose in the fill neck of the radiator? So with one of the hoses to the IACV disconnected I should see flow easily out of the hose and the stem from the IACV, correct?

Should I take the thermostat out as well?

[allencr]

Just touch it!
Do its hoses feel warm or do they not feel warm?
Warm = flow OK.
Cold = NFG

[ssspacely]

Just touch it!
Do its hoses feel warm or do they not feel warm?
Warm = flow OK.
Cold = NFG

The IACV feels cold to the touch when the car is running. I can't figure out why there is no flow through it. All the metal lines and hoses are clear. No blockage.

[yoshimitsuspeed]

You mean stick the garden hose in the fill neck of the radiator? So with one of the hoses to the IACV disconnected I should see flow easily out of the hose and the stem from the IACV, correct?

Should I take the thermostat out as well?

Yes exactly.
The heater and IACV should both bypass the tstat so it shouldn't matter.

[ssspacely]

You mean stick the garden hose in the fill neck of the radiator? So with one of the hoses to the IACV disconnected I should see flow easily out of the hose and the stem from the IACV, correct?

Should I take the thermostat out as well?

Yes exactly.
The heater and IACV should both bypass the tstat so it shouldn't matter.

Going to take off the iacv to make sure there is nothing blocking it. For some reason there is no flow through it and all the lines to the valve are clear. Put the hose right to the valve stem and I can't get any water to go through. This is the most frustrating troubleshooting I have ever experienced

[ssspacely]

Iacv off. Nothing is clogging it. I tried sticking it in 180 degree water to see if the valve closes. I don't know what to look for. I can still blow air through all the ports.

What am I missing?

[ssspacely]

Alright. The two hoses that lead to the iacv are disconnected. I can easily get flow through the hose on the right but the one port on the left does not allow flow through it. In the picture the rubber hose is disconnected. It's the metal stem that leads to the hard coolant pipes that run on the outside of the block beneath the intake manifold. My question is should I easily get flow through both hoses when the car is cold? Is flow through the back hose controlled at all by the thermostat?

[yoshimitsuspeed]

I am mostly positive that circuit should bypass the tstat and should flow properly when cold. Not 100% positive though. Either way I would say you have found your most likely culprit and should chase that side of the circuit till you figure out what is blocking flow.

[allencr]

Blow......

[ssspacely]

I am mostly positive that circuit should bypass the tstat and should flow properly when cold. Not 100% positive though. Either way I would say you have found your most likely culprit and should chase that side of the circuit till you figure out what is blocking flow.

Even with the thermostat out I don't get flow through the one hose. From this diagram, it's the hose that is leading to the IACV or to the throttle body. I have pulled all of the hoses off and blew air through them all. I must have missed something. I have checked all the hoses all the way to where they go into the firewall to the heater. If there was a block in the heater, would it prevent flow? I have heat so I really don't think it is the problem. I can't believe how difficult this is to locate.

[jondee86]

This is a brand new USDM set of water tubes...



And this is an old set of JDM water tubes...



Side by side comparison...



The fat pipe is the heater return to the suction side of the water pump,
so this is where the water goes when it leaves the AAV. The skinny pipe
connects to the heater outlet pipe at the back of the head, and this is
where the water for heating the AAV comes from. As you can see, it is
not a very complcated setup, so checking to see where the blockage is
should be quite straight forward

Oh, and at the rear of the head you should have one of these....



You need to check that the little side tube that sends water to the AAV is
not blocked. That would be a good place for a knob of sealeant to get wedged.

Cheers... jondee86

[ssspacely]

This is a brand new USDM set of water tubes...



And this is an old set of JDM water tubes...



Side by side comparison...



The fat pipe is the heater return to the suction side of the water pump,
so this is where the water goes when it leaves the AAV. The skinny pipe
connects to the heater outlet pipe at the back of the head, and this is
where the water for heating the AAV comes from. As you can see, it is
not a very complcated setup, so checking to see where the blockage is
should be quite straight forward

Oh, and at the rear of the head you should have one of these....



You need to check that the little side tube that sends water to the AAV is
not blocked. That would be a good place for a knob of sealeant to get wedged.

Cheers... jondee86

Well. Even though I feel like an idiot, it is fixed! The car finally idled normally. The problem was the small metal tube leaving the iacv was blocked by rust and junk. I cleaned it out well and all seemed to work.

Thanks to everyone who helped troubleshoot this problem. You guys were on point with the diagnosis. The first time I checked the pipes, I was rushing and didn't take the time I needed. It was a good learning experience.

Now I have to figure out how I broke the reverse lights.

[ssspacely]

Feels like a brand new car. Just wanted to share the experience. Here it is.