Jim Nowak

I'm in the process of getting my car back together after a rebuild. I've got a '79 928 2V with an Electromotive TEC II EFI engine management system, 85 5.0L 32 valve notched pistons, 944 heads, Devek Cams, Extrued honed Euro S intake and throttle body, 86 Euro injectiors/rails, and Jet Hot coated headers. Of course, I have already done all the other conversion pieces such as MAP, TPS, ETC, ETC.

There are a few issues that I need to sort. Is the CIS fuel pump compatible with the electronic injection or will I need to switch to a later model EFI fuel pump. I'm worried that the CIS pump will provide too much fuel pressure and overpower the injectors?

How do I hook up the tach to get a signal to the tachometer. In other words, what wire and where is it located in the bundle of wires on the passenger side of the engine compartment?

jpitman2

IIRC, pumps provide volume, the downwind system produces the back pressure, as long as the delivery rate is adequate. I ran my CIS car for several years with an S4 pump on it (based on the Bosch part-no) without issues, so I suspect the pump will not cause issues for you. I have been told that a CIS system using a non-CIS spec filter can be an issue duie to the higher CIS pressures, but have not seen/heard of a case of problems.
Wally will probably come in with the wire info, but there is a feed of distributor pulses to the fuel pump relay socket (to tell it to keep the pump running), on the very small pin, also IIRC. This might well be used as a tach feed. Or just locate the actual tach feed wire in the pod?
jp 83 Euro S AT 52k

Gary Knox

Jim,

Long time - no communications between us!! Do you still have the SEC? Did you know that Brent Von Behrens also joined the "SEC and 928" group in 2009? Hope all is well with you,

Gary Knox

Jim Nowak

Gary, I sold the SEC many years ago. I hope all has been well?

Jpitman2, thanks for the response. Where is that pin located?

Iwanna928

Jim I am jealous! That sounds awesome. Will you get it dyno'd? Sounds real strong, good luck with tieing it all together!

Stephen

Jim Nowak

I will get it dynoed but I need to find the tach input point from the engine bay. Anyone got the engine bay wiring diagrams for the '79?

jpitman2

If you pull the fuel pump relay (NOT a std one!) you should find one very thin/narrow pin (ie 2mm wide vs 6mm), which I believe is a signal from the distributor that rotation is occurring . Without this signal, the relay will not pull the pump in - prevents pump running and delivering gas if the engine isi stopped as in an accident. If you pick up the signal from that connector on the relay socket, it might give you enough to drive a tach. Dont quote me though as to it being 1 pulse per plug fire.
jp 83 Euro S AT 52k

Jim Nowak

Do you know what wire in the engine bay should be sending that signal?

jpitman2

I suspect you need a set of wiring diagrams for that data, unless Wally comes in, I would bet he knows which wire and connector on the bottom of the board is relevant. My wiring diags are at home. If you dont have any answers by tonight I will try to find the wire or socket code.
jp 83 Euro S AT 52k

Jim Nowak

Any luck finding the socket?

dr bob

Jim--

Tach signal from the ignition box comes into the CE panel at O7, on a solid green conductor from the ignition unit pin 16.

The pulsed signal from that unit is connected to the fuel pump relay pin 31b (relay is in position XVII) as noted by others, and is also shared with the AC compressor speed relay at pin 31b (relay is in position XI), out to the tachometer from the CE panel from G7 on a solid green conductor to the 3M connection point on the instrument cluster. It also comes out of the CE panel at Z4, but there is no wiring attached to that connector/pin per the wiring diagrams.

Jim Nowak

Thanks! I'll have to give that a try.

Jim Nowak

I wonder if our system needs some kind of signal booster? It doesn't seem to be recognizing the one from the Electromotive unit.