CIS to EFI conversion?
 

Ok gents. So I am sick of trying to keep this CIS tuned. I bought the 79 from my buddy Rob aka(BoiseShark). He did a ton of work to the old girl to get it up and running but we are still having problems keeping it running consistently. One time you strt it up and it's rich as hell... And the next time she runs pretty good. He had installed a new WUR from 928 Int. Along with new Merc injectors ect.

My thoughts are to swap the whole system over to the EFI (Ljet, ****Jet, or what ever the technical term for it is). off of my 1980 parts car. I am sure it's been done before, but I am looking for some input as to if I should do it or not. Obviously I would rebuild or refurb all the donor parts before they are installed.

Thought? Is it really worth trying to get the CIS running well which may mean a new fuel distributor ect..which aren't cheap. Or just update the whole system...

Thanks in advance.
Ramon

I'll be interested in answers as well as I will swap an 82 motor into my 78. Do I keep the CIS or go Ljet?

IMO, fix the CIS. Sounds like you just need to get that Distrib rebuilt and test or replace the AAV with a known good. Not much to the whole system in parts. Your halfway there.

The system is very dependant on proper pressures, so a gauge and free of vac leaks are VERY important.

I rebuilt my FD...made a few mistakes....once proper, it lasts....look on eBay, or in Leo's threads, there is a guy who rebuilds them for like 160$....

FI Change Over -
 

Hey Spooled, It is not that the swap from CIS to LJet couldn't be done, there are lots of good used parts around. It is whether the time and money involved would be worth the effort. I have helped sort out several versions of the CIS system used on some of the early Porsche, Mercedes, Volvo, etc over the years and when they are set up and tuned properly ran with reasonable economy and good reliability.

I have always found that the key to trying and straighten out a CIS system is patience (which my wife says I have none). Then make sure the fuel pressure is correct, the fuel distributor is spotless internally and the warm up regulator is working properly. There are also several good write-ups covering how each component should perform and even how to modify the warm up regulator to make it externally adjustable. This allows you to fine tune the transition during the warm up cycle better.

I'm sure you already have one of the CIS pressure gauge set-ups. It is literally impossible to troubleshoot, verify and monitor what is happening on a fuel system internally without one of these things.

Keep Us Posted and Good Luck, Michael

What is the CIS communities thoughts on the constant de-tune that it experiences. We have an air/fuel digital gauge and it always runs rich, but we can get it running acceptable at about 11.5 -9 by leaning out the air/fuel screw about an 1/8 of a turn, but then the next day it's doing the same thing and blinking below 10 so we adjust the screw again and bring it up to 11's. I remember checking the pressures back in the day and they were right where they needed to be. I even have an inline pressure gauge to make sure it's staying where it needs. I don't remember now the upper and lower limits, but I know the needle has stayed in the same place.

Question: If we have all the parts to swap over to Ljet, why not do it? If I had a toilet that always flushed, I think I'd modify the wax ring so I could replace the one that keeps getting my floor wet.

Has anyone done it before with any benefits?

Cheers SmileWavy

lol, you were answering most of my question as I was typing it JK.

Ever be interested in an all expense paid tune trip to Idaho? We'd even through in some of your vices. ;)

You really should R&R the CIS system. When you get them going they are very reliable. Get the gauge and R&R it. EFI is good but it's not original to your car... Your car will be more desirable, too, if you ever go to sell it without the CIS.

I bought a Euro S years ago without an engine. Had an 84 parts car with a good engine. Put the l jet engine in a cis car. Greatest difficulty was changing the fuel lines. L jet runs several more lines front to back and some of the lines have to be cut to remove from an assembled car.

Running more fuel lines sounds like a real pain, that kind to makes my decision for now.

Just wondering what years 928 had CTS injection?

sorry CIS

US 78/79 and Euro 78/83 were CIS.

Hello, need a fuel pump, my 928 is a 1980 with CIS, so what pump should I get? It has a 12mm banjo. Thanks, Steve