Hi all,

 

I'm sure this is a common problem with Z's, where for what ever reason the idle will just suddenly increase when the car is fully warmed up. I just want some input on reasons you have found for this and what can be checked out using a Conzult/Datascan.

 

Boost leak - Boost Leak Detector

Faulty temp sensor

TPS voltage - Conzult

Closed Throttle switch (should be on at idle) - Conzult

Malfunctioning/sticky (IACV-)FICD valve - Conzult

Malfunctioning/sticky IACV regulator - Needs to be checked manually

Malfunctioning/sticky (IACV-)AAC valve - Conzult

 

Cheers

 

Vijay

TPS voltage

Closed Throttle switch (should be on at idle)

Yeah, I get this too. Revs rise to just over 2k.

How can the throttle switch be checked?

> How can the throttle switch be checked?

 

with a conzult

 

But you can reset it manually: disconnect the big grey plug coming from the TPS while the engine is idling, wait 5 secs. and connect it again.

Best is to reset it after you have verified the TPS voltage is approx. 0.44 volt at idle.

Cheers Eric. Can a faulty temp sensor be determined with a Conzult by seeing an irregular temperature?

A faulty sensor is only detected if it fails completely

A sensor giving false readings is a bit harder to diagnose.

 

best is to start with a cold engine and verify the coolant temp is the same (or very near) the fuel temp.

 

Try to find out at what temperature the idle starts to rise and go into the "main signals" menu and manually alter the coolant temperature to see if has any influence on the idle.

 

In general, the coolant temp on a fully warmed up Zed with a good functioning cooling system should stay at around 82Celcius

mines between 75c and 85c in really hot weather, does idle high tho

Cheers again Eric. Anything else that would cause a high idle?

 

Vijay

Yeah, thanks for the info! :)

>> Anything else that would cause a high idle?

 

malfunctioning/sticky (IACV-)FICD valve

malfunctioning/sticky IACV regulator

malfunctioning/sticky (IACV-)AAC valve

 

also check the connectors of these valves (FICD + AAC connectors are hard to reach though)

 

 

>> 75c and 85c in really hot weather

 

is this with AC on or off ?

 

with AC on, the coolant temp is normally higher then normal, depending on the ambient temp it can range from 85 to 95 on a really hot day.

Cheers Eric,

 

Can any of those bits be diagnosed with a Conzult?

 

Vijay

the FICD can be switched with the conzult and is normally only used by/for the aircon.

 

 

the AAC valve can also be operated in the main signals menu of the conzult

When the engine is warmed up, the valve should be open for 15% (idealy)

 

 

The regulator valve can not be switched with the conzult (or any other diagnostic program) and needs to be checked manually

 

once again, cheers Eric :)

anymore reasons anyone can think of?

 

Vijay