Daewoo Tacuma 2 Litre Petrol 2004 High idle in hot weather

[106er]

I am asking on behalf of a friend who has a Daewoo Tacuma 2 Litre Petrol 2004 model:-
During the hot weather last year and this year, on occasions but not regularly when the car is stationary at say traffic lights the idle speed increases to 2500 to 3000rpm and will not come down again until you either drive off or switch off.  The latter once restarted cures the problem for the rest of the journey.

At first I thought it was seat to pedal interface problems (the driver) as he has big feet but it also happens to his wife.

The car has been back to Daewoo 3 times under warranty - they conveniently found nothing obvious and are not willing to go any further as the computer says no problems.  And of course because it is intermittent, it never happens when the garage have it.

Please help?  Someone must have an idea.

I have read the threads about idle control valve but not convinced yet!

Many thanx in advance.

[RobOneStop]

I WOULD BE CONVINCED
is yours the 2 bolt one one the side of throttle body?
if yes then take off and clean first also give breather pipe and throttle body a good clean

[106er]

Does any one else have this problem?  Or is this a one off.  Now the weather is hotter the owner is having the same problem - He hasnt tried the suggested route yet as its under warranty and wants more info so he can take it to daewoo with some more info.

[tim bowkett]

106er, i would take it to a independant that spec in diagnostics, i have had faults with these and it has been down to the throttle position sensor needing tweaking,if memory seves i think i drilled out the metal inserts and adjusted till it was at its lowest reading, the one i did had been to dealers umpteen times, and after the £150 bill for a idle spped control valve that did not cure the fault, and being told it could be because the headgasket might be gone they bought it too me, now it did take me an hour to diagnose and rectify,but well worth the £30 plus vat 

[Dave H]

IDLE LEARN PROCEDURE (2.0L DOHC)

Whenever the battery cables, the Engine Control Module (ECM), or the fuse is disconnected or replaced, the following idle learn procedure must be performed:
Turn the ignition ON for 5 seconds.
Turn the ignition OFF for 10 seconds.
Turn the ignition ON for 5 seconds.
Start the engine in park/neutral.
Allow the engine to run until the engine coolant is above 85°C (185°F).
Turn the A/C ON for 10 seconds, if equipped.
Turn the A/C OFF for 10 seconds, if equipped.
If the vehicle is equipped with an automatic trans-axle, apply the parking brake. While pressing the brake pedal, place the transaxle in D (drive).
Turn the A/C ON for 10 seconds, if equipped.
Turn the A/C OFF for 10 seconds, if equipped.
Turn the ignition OFF. The idle learn procedure is complete.

IDLE AIR CONTROL SYSTEM CHECK(2.0L DOHC)


Circuit Description

The Engine Control Module (ECM) controls the engine idle speed with the Idle Air Control (IAC) valve. To increase the idle speed, the ECM pulls the IAC pintle away from its seat, allowing more air to pass by the throttle body. To decrease the idle speed, it extends the IAC valve pintle toward its seat, reducing bypass air flow. A scan tool will read the ECM commands to the IAC valve in counts. The higher counts indicate more air bypass (higher idle). The lower counts indicate less air is allowed to bypass (lower idle).

Diagnostic Aids

If the idle is too high, stop the engine. Fully extend the Idle Air Control (IAC) valve with a IAC driver. Start the engine. If the idle speed is above 800 rpm, locate and repair the vacuum leak. Also, check for a binding throttle plate or throttle linkage or an incorrect base idle setting.

Idle Air Control Valve Reset Procedure

Whenever the battery cable or the Engine Control Module (ECM) connector or the ECM fuse EF6 is disconnected or replaced, the following idle learn procedure must be performed:
Turn the ignition ON for 5 seconds.
Turn the ignition OFF for 10 seconds.
Turn the ignition ON for 5 seconds.
Start the engine in park/neutral.
Allow the engine to run until the engine coolant is above 85°C (185°F ).
Turn the A/C ON for 10 seconds, if equipped.
Turn the A/C OFF for 10 seconds, if equipped.
If the vehicle is equipped with an automatic trans-axle, apply the parking brake. While pressing the brake pedal, place the transaxle in D (drive).
Turn the A/C ON for 10 seconds, if equipped.
Turn the A/C OFF for 10 seconds, if equipped.
Turn the ignition OFF. The idle learn procedure is complete.

All courtesy of...http://chevy.mrmax.dp.ua/EN/documents/Tacuma-Rezzo/start_Tacuma-Rezzo.html


Regards
DaveH

[Robnorthwest]

These guys are spot on. I should know, I run a Leganza and that had the same problem. On the Tacuma, the IAC is bolted onto the inlet manifold and cleaning often improves (though won't totally cure) the situation. There is another method you could try, which can be found in the Daewoo section on this site. I have used this other method 4 or 5 times on different Daewoo's, with 100% success.