Jeff’s PEFI Wiring Harness, Your input please… Options

[JeffBowlsby]

PEFI (programmable electronic fuel injection) is here to stay and will become a necessity in the future to keep our 914s on the road and I want to be part of that revolution. (IMG:http://www.914world.com/bbs2/html/emoticons/burnout.gif)

Studying the different available PEFI systems and 914/4 engine layouts, they are all very similar in terms of their electrical and harness requirements. So I have been working with other club members (EE’s!) who shall remain nameless for the moment, to develop a universal 914 fuel injection wiring harness specific for the 914/4 or type 4 engine, that can be easily adaptable to most of not all aftermarket programmable electronic fuel injection (PEFI) systems. I have attached a couple of diagrams of our ideas and would appreciate anyone’s feedback, because this harness is for all 914/4 owners and I want it to serve our needs to the fullest. If its not a good solution that will serve most peoples needs, then I won’t make them.

The concept of this harness is clear: Create a PEFI harness that is simple, and adaptable to all or most aftermarket PEFI systems, built of high quality parts and workmanship for durability, and be reasonably priced. I realize it won’t meet everyone’s needs, but it should be a good solution for most. My intent is that it be Plug N Play and take the R&D, pain and expense out of building a harness that most dread. Buying this harness gives you reliability and gets you on the road much faster than having to build your own harness. I know some of the PEFI systems have harnesses available, but they are not the best solutions, they are not complete, and they are not made for the 914, although they can be a good start. My PEFI harness features include:

FI systems – A fuel-only PEFI system would be nearly Plug N Play, which I think most 914 owners will want when their MPS dies, most do not want to fuss with complex systems, but this harness will work for those who do. If someone would package an ECU with preloaded maps for specific engines, the install would be nearly painless. I bet the time to install a simple system could be accomplished in an afternoon if coordinated. If ignition control is needed, then my PEFI harness with additional wires, has the expandability to accommodate your needs.

2-piece harness with a weatherproof main disconnect in the engine bay – This allows the production of a standard engine harness configuration which will universally fit all type 4 engines, 1.7, 1.8 and 2.0L. The ECU harness segment can be made to the length you require, so the FI box can be located in the cabin or anywhere you select. The main disconnect allows the harness to penetrate the firewall and become mounted to the chassis, and also allows easy engine drops. Wires on one end of the ECU harness are long (is 18 inches enough?) and not terminated, so you can hook them up to whatever FI equipment in whatever arrangement you want.

Auxiliary wires – The PEFI harness connects all the standard 914/4 engine mounted FI sensors and fuel injectors to the ECU controls – TS1, TS2, TPS, and Tach. It connects to power and the fuel pump relay at the stock relay plate and to grounds in the stock engine case location. It is convenient to use the stock D-Jet AAR, controlled through the ignition harness, but if you want a fast idle solenoid or even a stepper motor you can have it. The standard harness includes 4 undesignated auxiliary wires for your use which might serve a fast idle solenoid, stepper motor or ignition trigger. If 4 extra auxiliary wires internal to the harness are not enough (it will be for most people), then I can provide as many as you like for an additional charge using a different main disconnect configuration.

TPS – At additional cost, I will provide a new TPS potentiometer with a disconnect and casing, or you can send me your TPS and I will install the disconnect and casing.

Connection hardware - D-Jet hardware is standard (new boots!) so you can reuse the stock FI components. Optional L-Jet connectors can be installed for a small cost increase. The harness can be configured for FI power resistors, or not, depending on your needs.

WBO2 cable – Use the cable from the WBO2 manufacturer and run it separately from the FI harness to keep things easy and protect the WBO2 warranty.

High Quality - The PEFI harness cable is fully cased to protect the internal wiring from chafing, fluid contamination and heat damage. All new, high quality parts and workmanship are used in its construction, this harness does not use any old parts and there is no core charge, although I might buy your D-Jet harness for my D-Jet harness customers. The Tach wire includes a shielded ground.

Price – What might all this cost? I honestly don’t know yet, but considering the parts cost purchased in bulk quantities, and the amount time required to make them, I think I can make them available in the $400-450 range or thereabouts. Is this price range reasonable? If not, where does the price need to be for you to buy one?

So talk to me my esteemed colleagues…and thanks in advance. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) My intention is to bring these on line in the next few weeks if possible.

[Jeff Nelson]

I think that ignition control is an important part of an overall strategy. That does not mean that DIS is a requirement however. As soon as the distributor is eliminated for timing then you've got to drop the motor to mount the crank position sensor and magnets for a HALL-based system or a toothed wheel for VR. On top of that there is fabrication needed to mount the sensor and wheel. This is more than many are willing to do if they just want to replace their OEM system with a modern, programmable system.

A distributor still works quite well for distributing the high voltage for the spark plugs. For most applications a multiple coil setup is not justified. If the distributor is mechanically ok then the timing signal (Tach) should be fine. If the OEM distributor is worn out then just about anything that fits is viable. No vacuum needed, no mechanical advance. The dizzy used in the later Vanagons appears to be a good choice. These use a HALL sensor and are already locked.

The big hurdles in doing a PEFI retrofit are researching options, gathering parts, wiring, fabrication and programming. For someone looking to minimize the down time for replacement of the OEM system, eliminating the wiring, fabrication and programming would go a long way. It is true that each system would ideally be programmed (tuned) for each application. This was not the case for the OEM setup however. That is, except for very limited adustments, you don't have to tune it for each application. If you have the correct complement of parts it just works. For a close to stock engine there should to be a set of ECU parameters that will work as well as the original system. A WB O2 is not needed in every case. On the other hand, until someone does the work and makes it available everyone gets to program their chosen ECU.

I'll describe my situation because I think it is fairly typical. My engine is a recently rebuilt 2L. It is stock except for a Webcam #73 camshaft. It runs pretty good but the stock D-jet doesn't handle the cam real well at idle. I've got a good MPS and a spare. My harness is original and getting a little crunchy. I'd like to get my engine running well with the non-stock (but mild) cam and generally upgrade the wiring. ECU control of ignition is desirable as well. Megasquirt is attractive because of low cost and a large user base with an active newsgroup. As I look at various 914 installations, they are all different. I've had to pick and choose what I'm going to use for my installation. There is some satisfaction in doing this but if someone gave me a specific list of parts and a configuration I likely would have used it. I think having a specific configuration would suit many of us. The harness that Jeff proposes eliminates some of the messier aspects e.g., where to place relays. His proposal addresses the basic requirements and is still adaptable to specific needs. I want one!