1mz high idle when clutch dipped.

[doogal44]

Hi all
I don't know if the car has always done this but only noticed it today.
When going along in 4th and 5th at about 50 mph or over if I let off the throttle and dip the clutch the revs will stay up around 2000-2500rpm?
Is this normal or do I have a problem?
At lower speeds and revs it behaves normally.
Could it be an airless or speed sensor causing it to do this?

Thanks for any help in advance.

Aaron

[rainen]

Thats a strange one. I'm no expert but the only time something like this has happened on my 1MZ it was the IACV stuck. But in that senario the revs stayed high no matter what gear or speed I was doing when I dipped the clutch. Solution was to pull the connector off the IACV for a short while and put back again. This sorted mine out. Only had it happen once.

[Paul Woods]

Isn't dipping the clutch and coasting at 50mph an abnormal thing to do though?

[doogal44]

I agree it not a normal thing to be doing but I noticed it was upping the revs when I was changing down to 4th from 5th so I started dipping the clutch at different speeds to see what was going on.

[Paul Woods]

Not something I have ever noticed to be honest, probably an auto ECU side effect, they do behave differently without the automatic gearbox inputs etc.

[doogal44]

Ok
So the car smells like it's running rich.
I hooked up torque and had a look at the data.
All seems to be running as it should apart from the o2 sensors.
I am getting "open loop due to insufficient temperature"
I also have no voltage readings for both o2 sensors.
I'm guessing this is my problem as the car doesn't know what it's doing.
I do not have any fault codes stored though.
Is this the coolant temp sensor that feeds this?
My coolant temp seems to be reading correct?

[Paul Woods]

When you first start up it should be in open loop until the engine warms a little, then the ECU turns on the O2 sensors and it will go into closed loop.

What temperature reading is being displayed from the EFI temp sensor?

[doogal44]

Hi Paul
I don't seem to be able to find efi temp.
The coolant temp at the time of looking was 86-90 C
If one sensor goes out does it keep it in open loop?
I will check the resistance of the sensors later to see if they are reading correct.
Any other ideas what I should check if the o2 sensors are OK?

[Paul Woods]

If you are seeing 86-90 in torque then that is fine, it should be in closed loop at those temps and the EFI temp sensor must be working.

If one sensor goes bad it will just put that one bank in open loop, so one bank will be running safe mode, not both.

Quick test, unplug one of the sensors, and using a multimeter test the four pins in the engine harness side for 12v ignition power, probably a black/red stripe wire (can't remember offhand), so turn ignition on and probe all four wires, one of them should be showing 12v.

[doogal44]

Thanks Paul I will check that.
If I'm not getting the 12 volts what will likely be the cause of this? Is there a fuse or relay I can check or will it be another input that the ecu is missing?
I definitely have neither bank working.