Help with L-Jetronic

[E9Paradise]

I have a 74 coupe with a L-Jetronic FI system from a 76 3.0csi (Bavaria). The FI was recently professionally installed (on the stock motor). It runs great except for the following things.

1. When cold I turn the key to start, the starter engages, the engine begins to fire up but the starter keeps running. I turn it off immediately and try again. The engine fires up and the starter motor doesn't stay running. This happens everytime it's a cold start.

2. Once it's running it idles badly for about a minute then it smooths out and runs at a high idle.

3. When the engine is running cool (a cool day, not overworking the motor) the idle is high, like 1400-1500 rpm. If the temp gauge climbs at all and the engine is running warmer the idle comes down 2-300 rpm. If it's a hot day and I just came up a hill and stopped the idle gets really low and sometimes the engine dies.

Any L-Jetronic gurus around?
Thanks,
John

 

[MichaelP]

The FirstFives E12 page is the go-to source for L-jet. Here's one of their tech pages about the auxillary air valve that seems to get at your problem. You'll need to determine which aux air valve you have in there.

If that doesn't help, scope out the rest of the FirstFives tech faqs or drop a note on their forum. They're a friendly bunch:
http://www.firstfives.org/

 

[E9Paradise]

Michael,

Thanks for the great info. I'll head over to the firstfives site tonight!

John

 

[Tierfreund]

Then high idle is most likely the aux air valve, as stated by pp or the water pipes running coolant to it

The starter issues of course are unrelated.
The starter mechanism may be sticky so it doesn´t properly disengage. Stickyness might be worked loose by first start and/ or heat so it only happens on first cold start. I´d pull the starter, dissasemble the engaging mechanism, clean and grease everything and put it back together and in.

 

[E9Paradise]

That sounds like a good course of action, Tierfreund. I think you are correct about the starter, it has been sounding different too. I have checked the condition of the battery and it is good.

Thanks again John

 

[Honolulu]

yo, waitaminnit

pulling the starter for anything is bad enough on a carbed car, let along one that has the injection manifold hanging overy everything. Save yourself some time....

Before you pull the starter, short the pair of terminals at the solenoid to activate first only the solenoid. (sorry I can't tell you which pair just now). You should hear the starter pinion activate and release. If it does not sound like it is cleanly and completely working, only then would I attempt to remove it.

De-soldering is required to separate the starter from the solenoid IIRC.

I would not want to R&R the starter, only to find it's something else. It's real difficult to get at, and you will want to assess the problem before charging into it hell-for-leather. That said, I suspect I'd be heading in the same direction but only AFTER assessment. I've never had solenoid or pinior release problems in all the 18-odd high-mileage bimmers I've had. But you could...

 

[E9Paradise]

Good point Honolulu. I'll do some diagnosing before tearing into it. It's just the weirdest thing, the way it hangs on that first time and then it's fine. I was thinking there was some FI related relay that might be connected in the solenoid circuit.

Thanks for the tip. John

 

[Tierfreund]

Sorry, never pulled a starter on an M30. The last starter I pulled was on a VW Golf and that was easy. I didn´t know it´s a pita on the E9 (I find most other things on our old BMBusses are quite easy to work on)

So, I didn´t want to send anyone on an unneccessary yourney to greasy masochism. The idea of donig some proper diagnostics first of course should be much applauded.

Good point.