The words idle, problem, Porsche and 944 seem to appear more times together on any forum than any other niggle to do with the car. The reason they appear so frequently is that there are a number of situations and/or combination of situations that can cause the idle speed of your 944 to behave erratically as the following clip of my own car shows.
You will find a lot of posts talk about the cause being vacuum leaks or something known as the 'Idle Control Valve' or 'ICV' as it is often abbreviated (the Porsche parts catalogue calls it the 'Idle Speed Adjuster'). What is not often clear is that the ICV only appears on the Oval Dash models of the 944. The difference in configuration between the Square Dash and Oval Dash models can be seen in the two diagrams below.
Square Dash configuration
Part 9 - Auxiliary Air Regulator (944 606 103 00)
Part 16 - Electric Air Valve (944 606 215 00)
Oval Dash configuration
You will find a lot of posts talk about the cause being vacuum leaks or something known as the 'Idle Control Valve' or 'ICV' as it is often abbreviated (the Porsche parts catalogue calls it the 'Idle Speed Adjuster'). What is not often clear is that the ICV only appears on the Oval Dash models of the 944. The difference in configuration between the Square Dash and Oval Dash models can be seen in the two diagrams below.
Square Dash configuration
Part 9 - Auxiliary Air Regulator (944 606 103 00)
Part 16 - Electric Air Valve (944 606 215 00)
Oval Dash configuration
Part 18 - Idle Speed Adjuster (930 606 161 00) ... aka ICV
I have no idea why Porsche changed the design but if you are an oval dash owner you may want to check out this post if you want to test your ICV. If you're a square dash owner then read on.
THE HOW TO
(Amateur mechanic job time approx. 30 mins)
Fortunately the fix for my 1984 square dash model didn't require checking for vacuum leaks. The problem was actually dirty electrical contacts on the Auxiliary Air Regulator and Water Temperature sensor on the radiator. This occurs due to the constant heating and moisture that the engine bay is subjected to.
Auxiliary Air Regulator
Water Temperature Sensor (located top corner of radiator on the air box side) - Top view
Water Temperature Sensor (located top corner of radiator on the air box side) - Bottom view
To clean the contacts simply pull the connectors off their plugs, spray the contacts with some electrical switch cleaner and before reattaching apply some switch grease to the contacts to prevent moisture from corroding them in future.
THE HOW TO
(Amateur mechanic job time approx. 30 mins)
Fortunately the fix for my 1984 square dash model didn't require checking for vacuum leaks. The problem was actually dirty electrical contacts on the Auxiliary Air Regulator and Water Temperature sensor on the radiator. This occurs due to the constant heating and moisture that the engine bay is subjected to.
Auxiliary Air Regulator
Water Temperature Sensor (located top corner of radiator on the air box side) - Top view
Water Temperature Sensor (located top corner of radiator on the air box side) - Bottom view
To clean the contacts simply pull the connectors off their plugs, spray the contacts with some electrical switch cleaner and before reattaching apply some switch grease to the contacts to prevent moisture from corroding them in future.
