How do you adjust idle on 1975 1.8L l-jetronic Options

[steveneashcraft]

Assuming that everything is right. Where is the idle adjustment on a 1975 Porsche 914 with a 1.8L engine with l-jetronic. Car is absolutely stock.

[Cap'n Krusty]

The "hold the idle steady" comment scares me. Here we go, brief version. To set the timing, remove AND PLUG the 2 vacuum lines at the distributor. The idle speed should rise substantially. Don't have any? Stop right here and get the right distributor. Turn the air bleed screw in until the idle is at 800 RPM. Remove the cover of the timing mark observation hole and shine the timing light in there. Look for the mark, which is red. If you don't see it aligned with the "V", make it do so. If the car runs at all well, it's gonna be close enough that only a minor adjustment should be necessary. Tighten the 10mm locking nut on the distributor clamp, and recheck the timing again. Readjust as necessary (clamping it down frequently moves the distributor slightly). Unplug and reattach the hoses, and turn the air bleed screw OUT (CCW) until the idle speed is again at 800 (or 850) RPM. You're done. If you used ANY other method to adjust the timing on your L-jet equipped engine, you did it wrong.

Have a nice day .............. The Cap'n

[steveneashcraft]

The "hold the idle steady" comment scares me. Here we go, brief version. To set the timing, remove AND PLUG the 2 vacuum lines at the distributor. The idle speed should rise substantially. Don't have any? Stop right here and get the right distributor. Turn the air bleed screw in until the idle is at 800 RPM. Remove the cover of the timing mark observation hole and shine the timing light in there. Look for the mark, which is red. If you don't see it aligned with the "V", make it do so. If the car runs at all well, it's gonna be close enough that only a minor adjustment should be necessary. Tighten the 10mm locking nut on the distributor clamp, and recheck the timing again. Readjust as necessary (clamping it down frequently moves the distributor slightly). Unplug and reattach the hoses, and turn the air bleed screw OUT (CCW) until the idle speed is again at 800 (or 850) RPM. You're done. If you used ANY other method to adjust the timing on your L-jet equipped engine, you did it wrong.

Have a nice day .............. The Cap'n

I usually don't respond to comments that don't have anything to do with my post but I can't resist. I need to know how to set the idle on a 1.8L L-Jetronic. I know how to set and check the timing. I can't get the car to idle without having someone or something pull on the throttle cable. (i.e. someone hold the idle above the rpms needed to not stall). It seems like the easiest way to do this is to have someone sit in the car and watch the tach, listen to the engine, and hold a steady 900 rpm. Vacuum lines were set up to check the timing. It was correct.

If you know a better way to check the timing on a car that runs fine but dies from a low idle condtion please let me know.
If you don't give it any throttle after the car starts the car stalls. I know I could check the static timing but since at a constant 900 rpm the timing is spot on I don't think I need to.

Car starts when it is cold. Car starts when it is warm. It just doesn't idle.

The mystery is still "HOW DO YOU SET THE IDLE ON A PORSCHE 914 1.8L (1975 California car).
If the car won't idle and when you pull the 'The big fat screw on the throttle body' and can see the top of the butterfly valve what should you do next. Since 'The big fat screw on the throttle body' on my 1.8 doesn't have anything that I can see to adjust the idle I need some advice from someone who knows if there should be something under the 'The big fat screw on the throttle body'. At least one very helpful forum contributor checked his 1.8L throttle body in his basement and said there was nothing under the screw except a view of the top of the butterfly valve. I thought it was a rod but after checking my throttle body I have determined the helpful forum contributor was right. Thanks for some useful info.

So a few questions:
1) What should be under the air bypass screw on throttle body on a 1.8L L-Jectronic? On a 2.0L D-Jetronic there is a needle valve, spring, and needle seat under this screw.
2) If the answer to 1 is "nothing but a view of the top of the butterfly valve" then how do you adjust the idle?


Sorry this is so long but I'm a newbie to this forum and hope to find someone who can answer my question about how to adjust the idle on my car assuming that everything is correct except for the idle. Even if the timing on my 914 was wrong it would be great if I could just get an answer to "How do you adjust the idle".

Hope I haven't offended anyone. Thanks and have a nice day.

[Dave_Darling]

1) What should be under the air bypass screw on throttle body on a 1.8L L-Jectronic? On a 2.0L D-Jetronic there is a needle valve, spring, and needle seat under this screw.

There is no needle valve under the screw on a 2.0 throttle body. The screw itself is a valve; the end of the screw blocks a hole that goes through the throttle body from "upstream" of the throttle plate to "downstream". This hole bleeds air through it; the amount depends on how far in the screw is or how far out it is backed.

The 1.8 air bleed screw is the same way. The end of the screw plugs a hole that is going through the throttle body. Screw it in all the way and very little air goes through. Unscrew it and more air goes through, raising the idle.

--DD