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Sat Jul 12, 2008 7:34 am

HELP,MY 90 VANAGON WILL NOT IDLE WHEN COLD.WILL START AND GO TO 1000 RMP AND SLOWLY DECREASE UNTIL IT QUITS.VAN HAS GOOD FUEL PRESSURE AND NEW AIR FLOW METER,ALSO NEW COOLANT TEMP.SENSOR
THE MOTOR RUNS AS IT SHOULD AFTER IT WARMS UP VAN HAS AUTOMATIC TRANSMISSION AND A/C

Sun Jul 13, 2008 8:49 am

Check that the throttle position switch is properly adjusted. Also check for vacuum leaks and clean the ground connections in your engine bay. These things are all free and could easily solve the problem. If these don't work replace the temp2 sensor. They often fail and are very inexpensive. If you still have problems, let us know.

Mon Jul 14, 2008 7:21 am

are the coolant temp sensor and temp sensor ll two different things?also what is the function of the spring on top of the throttle valve and what position should it be in.thanks for your help!

Mon Jul 14, 2008 7:55 am

Temp sensor and temp sensor II are different.

The temp sensor is on the thermostat housing facing the front of the van. It sends a signal to the coolant temperature gauge on the dashboard. If that's broken it won't affect the way your van runs.

Temp sensor II is on the thermostat housing facing the left (driver's side) of the van. Usually a blue plug attached to the sensor. This sends a signal to the computer that adjusts fuel injection. Make sure that the connection from the plug to the sensor is clean and tight. Or, just replace the sensor with a new one, because they don't last forever and they're cheap.

Throttle Position Switch is explained in this post:

http://www.thesamba.com/vw/forum/viewtopic.php?t=298058&highlight=tps

Very important to have it adjusted properly for a steady idle and good running. Although you may be able to adjust the TPS by listening for a "click" at closed throttle and wide open throttle, this is an inexact method. Better to use a digital multimeter as shown in the link above.

Along with the TPS and the temp II, the other most common poor running issue comes from a bad oxygen sensor. Your van's symptoms do not sound like an Oxy sensor problem, but for future reference: if the van hesitates and runs rich it may be a bad OXS or an OXS wire sheath that's grounded on the coaxial wire.