HELP!My914s dying

Randy Hursh · 07-19-2000, 05:00 PM

my72 914 runs great when cold but when it gets up to temp it dies at idle.rpm seems low when cold can this be adjusted with fi like a carb ?also notice an occasional backfire on decompression. any help would be appreciated. this is my first 914 and is greek to me.

Germain · 07-19-2000, 06:02 PM

Ah, yer first 914, welcome to the world of Dr. Porsche's fuel injection

Okay, first you can adjust the idle with the throttle screw, located on the drivers side. It should be a flat blade, just turn to adjust it.

When the engine gets warm, the cold start valve and the aux air regulator stop "working", it may be that once warm, the idle is not set high enough to keep it running.

Also, the throttle position switch doesn't start working until the car is cold, or some of the sensors. As a fact with most cars, very few sensors do anything when the engine is cold. Basically the car dumps a butt load of air and fuel into the engine and is happy. Now of course some sensors do do work, but not all.

What I would recomend, is to look up the k-jet F.I. artical written by... (I'm sorry I don't remember, and I don't have my bookmarks on this computer). Search these messages for k-jet (kjet), and a message posted by me. You will find a link to the site, go there and read it in you spare time. Very good artical on this stuff

.

Good luck, and once you have it solved, you can help me with mine

John Rogers · 07-19-2000, 06:05 PM

Find the FI trouble shooting article in the tech session on this site and become familiar with all the parts and procedures. Sounds like the warm idle is too low and when the warmup valve shuts off the extra air it passes when the engine is cold the engine dies. There is an air adjustment on the front-left side of the throttle body that lets air past the throttle plate at idle and you unscrew it to speed up the idle. Good luck.

JP Noonan · 07-19-2000, 08:16 PM

...just to by a ninny. It is a "D-Jetronic" not a "K-Jectronic" the K-jet is used on some 911's it is also known as C.I.S. or Constant injection System.

I think the throttle screw is a good place to start. Then read the plugs (you mentioned a backfire in the intake) you may also have a leaking cold start injector (also known as the fifth injector or cold start valve) which is makeing things way too rich when warm.

Aslo, check the idle mixture knob on the brain. It is a grey knob (the only one on the brain) I think Clock Wise richens and CCW leans. Try it both ways (the tech article gets more indepth) if the engine speeds up then the mixture is leaning out. If it slows down it is getting richer, if it "hunts" (cycles up and down) then it is too lean.

Another thing that affects idle is the timing. Check the Dwell and THEN the timing. Heck if the car is new to you spend $40-$50 and tune it up. Plugs, points, cap, rotor, timing dwell, fuel filter, air filter, fix all the vacuum leaks, and most certainly CAREFULLY INSPECT ALL THE FUEL LINES. Unlike carberated cars the fuel hoses in the engine compartment of the 914 are at 30-40 psi. A small leak sprays gas all over the hot engine. Not good.

here they are
the D-Jet article

http://www.914fan.net/djet.html

and the main site

http://www.914fan.net/

[This message has been edited by JP Noonan (edited 07-19-2000).]

Germain · 07-20-2000, 04:55 AM

hehe, guess I've been working on my friends 911 too much

Sorry about the confusion. It is a DJet, and now that I'm at work, here is the artical written buy Kjell Nelin. This will help alot.
http://www.914fan.net/djet.html