912E L-jetronic HELP!

[csnitker]

Looking for some advice on trouble shooting the L-jetronic FI on my 912e...
Just completed a tune up, valve adjustment, plugs rotor and cap. Car idled fine before tune up, now when I start the car it idles normal at about 9000 rpms but as soon as I start to drive the idle raises and stays at about 1800 rpms. I can shut it down and restart it and idle is back to normal until I depress the accelerator. I have checked for vacuum leaks, tried adjusting idle and co2 settings with no luck, Any suggestions would be appreciated otherwise it looks like I need to find me a Porsche mechanic. Thanks

[WFBowen]

When the motor is in it's "high idle" state, can you disconnect the throttle cable at the throttle valve to see if it then drops? Are you sure none of your vacuum hoses (especially to the distributor) got switched around?
Here's a good troubleshooting guide for the 912E:
http://www.texas912.org/912E%20Tech%20Data/912E%20FI%20Technical%20Manual.pdf
Good luck,
Bill.

[MPucino]

I have the same problem with my e. starts and idles fine, but if I rev the engine up it stays at a high idle, like 2800 rpms. I have to lug it down to idle. And it idles fine until I crack the throttle. Did you find out the problem. I have checked the obvious ,throttle plate,vacuum leaks, tune up. Thanks Mike

[csnitker]

Had the same problem. When I purchased my E I noticed that the vacuum line to the anti back fire was disconnected and plugged. I reattached the hose to the anti back fire valve and I experienced the same issues you are experiencing. Disconnected it and it idles fine. Unfortunately if it is the back fire valves they are impossible to find. Disconnecting and plugging the lineman have consequences like back fires and damage to your AFM. Good luck.