1979 320i High Idle

[Jaberzz]

Hey guys, I just recently purchased a 1979 320i and am trying to get some assistance on getting it running well. The car runs but as soon as you start it up, it idles right up to 2000 RPM. Moving the idle adjustment screw doesn’t change anything. I have a theory on why it is idling high and I was wondering if anyone here would agree or let me know to start elsewhere.

When I rev the engine even a little bit, I hear a whistle noise and from reading this forum, I gather it is from the fuel injectors caused by the kjetronic being adjusted to run too rich. I believe the reason it was adjusted rich was because of a vacuum leak.

Am I making sense or is what I’m saying way off? This is the first car I am really going to work on, besides smaller stuff on my E46.

Thanks!

[Somjuan]

Does it slow down after a few seconds?

[Jaberzz]

Does it slow down after a few seconds?

I ran it for about a minute and it did not change at all.

[dreiermann]

When I had that, it was a combination of the previous owner having some of the vacuum lines wrong, and the throttle cable/throttle stop was not installed correctly. Make sure that the throttle cable is slack during idle before you adjust anything else.

[Jaberzz]

Before we adjusted anything with the Kjet, we found a vacuum leak and after fixing that, it dropped the idle to around 1000 RPM. We than tried to fix that whistle noise, which we thought was a fuel injector being caused by too rich a mixture, so we ended up turning the mixture screw CCW almost two turns because the whistle never went away. Someone came and helped up and discovered that it wasn't actually a whistle noise coming from the injector and was instead a slight vacuum leak. So we went to start the car again and nothing. We took the spark plugs out and discovered they were drenched in fuel, so we assume it was because we changed the mixture screw too much, so as of now I believe the car will run after we get the fuel mixture readjusted. Do you have any tips on getting that done? Its grossly misadjusted right now.

Thank You

[epmedia]

There are so many possibilities happening. Before tinkering with the fuel mix, you need to first ensure the 3 pieces of fuel hose on the suction side of the external fuel pump are not the original 'cloth braided' type - because if they are, they're sucking air bubbles. All 3 pieces connect to the metal 'Y' fitting at the suction side of the external fuel pump. May want to also check the long suction hose connection under the back seat, under the access cover.

Also change the fuel filter if you have no idea how old it is. I recommend draining the filter into a clean container to get an idea of what's inside the fuel tank(s).

[Jaberzz]

There are so many possibilities happening. Before tinkering with the fuel mix, you need to first ensure the 3 pieces of fuel hose on the suction side of the external fuel pump are not the original 'cloth braided' type - because if they are, they're sucking air bubbles. All 3 pieces connect to the metal 'Y' fitting at the suction side of the external fuel pump. May want to also check the long suction hose connection under the back seat, under the access cover.

Also change the fuel filter if you have no idea how old it is. I recommend draining the filter into a clean container to get an idea of what's inside the fuel tank(s).

The car was running at 1000 RPM after fixing a vacuum leak. We than thought we heard a whistling fuel injector so we tried leaning out the mixture. We than figured out it wasn’t an injector whistling but instead another vacuum leak, which we fixed, but now we are stuck with a badly misadjusted mixture. What is the best way to reset it to something the car will run on?

When it was running, the car was running quite well and the only issue it was having was that whistle we thought was the injector.

I will check the lines and the fuel filter as well, thank you!