When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Speedtoys, That is not good story with a happy ending. I was told the Computer has transistors that can burn out and control the ISV. Also that the TPS can fail to turn the idle out of the WOT mode. Buying that too. Will test the old one later today when I pull the Throttle body again. Will test the connections through the bracket by the Temp sensor II as well.
Just wondering if your idle goes up like mine as the car warms. Bought his one and hope it is the right one and two it solves my issue.
If she finds the idle issue I an the community would love to hear what the idle error was caused by. I'll be about $1500 worth of parts into finding my fast idle and the general clean up of the top. Mostly tired of tearing in apart trying stuff and then having it idle fast again time after time. The car does run smoother and my smoke tests are now showing 0 leaks. Even replaced the Vacuum control to the Gas tank vapor collector. Still have not installed the vacuum activated Fuel dampners and Fuel regulator but their on the list. So many inputs into the Idle speed it is worth changing the LH if one has a spare.
Cheers, Steve
Well the Vacuum leak I felt was causing my idle to go high as the car warmed up was the Idle Control Valve. Had about given up on Vacuum but as it turned out the leak was internal. Out of view of the smoke tester.
While I was working to clean up the Throttle body and the Airflow casting mounts I had the ICV out and should have tested it.
Center pin as ground and pin left 12 volts to open or close. Then switch the 12 volts to pin 3 for the opposite action. The pins will also read about 20 Ohms from pin to ground. My new Bosch Valve closed instantly but needed to get a tap to open. It worked fine when installed.
Just a good test to know. Thanks very much for the comments and suggestions.
Cheers, Steve
"how did you determine it was leaking" My experience with cars told me my faster idle as the car warmed up was most likely a vacuum leak. As a vacuum leak gets worse the car will increase idle until they stall. Secondly used the LED blinker test to set the idle mixture so the O2 sensor is happy. To do that I had to significantly richen the mixture from the stock setting for the MAF of 380 Ohms. When my O2 sensor was happy it was between 650 to 700 Ohms. I went through a detailed search for vacuum leaks and after the smoke test conformed it was tight it was unchanged in its faster and faster idle as it got hotter. The experts gave me a list of possibilities and some info how how the car adjusts the idle as the car goes form cold to hot and back to cold. Since I believed the core issue was a too lean car and the ICV if not working would cause that I bought one. Tested the new one and it worked pretty well wit ha 12 volt test. not much air could pass when closed and wide open when open. I also noticed that when you tap the valve without the motor holding the valve it opens as it vibrates. So, The normal failure position would be too lean. I was told the Computer board has contacts that can fail as well but I figured the ICV was the place to start. PorKen has a great topic showing how they look inside, how they work and why they fail. This part was scrapped in only two years of use by Porsche on the 928. Then I understand they switched to a solenoid type operated value. Much more reliable than a reversible motor to close and open a valve every time you drive the car. Finally The ICV was a consistently mentioned suspect by the group. This is my first modern fuel injected car I have done much work on. Learning a lot. One more likely source was the Temp senors. My tests of those showed mine seemed OK.
Anyway, On to the next phase of deferred maintenance. Replacing the rest of the Air flow sensors and switches just to make the car reliable as I can. Then Oil pan gasket motor mounts and the steering rack. The knowledge of the forum is fantastic. Sharing what I learned is the least I can do in return.
Cheers, Steve
01-01-2017, 05:40 PM
