1600 exhaust - FI - question

[raygreenwood]

Well...there's rebuilding...and reproducing. Only the very very best harnesses are worthy of rebuilding. Those are few and far between for two reasons (a) sheer age at this point (b) the nature of the terminals. IIt was a very very bad design.

A few things to remember:

(1) The wire quality used in those days...though some of the best for its time, is nowhere near as good as what you can get now. For that reason, wiring length of certain paired functions like....say all four sets of injector wires and grounds, both wires of a two wire resistor based circuit like the intake air temp sensor..etc...had to be as equal length as possible. In a system this simple...with very clean wires these days...that is no longer true.
(2) The plugs for D-jet had issues. By this I mean the plastic part alone. They were nylon and got brittle with age and that caused cracking and fit issues.
(3) The terminals were standard female terminals...only miniature. You see several finishes appliedto them. Some of the originals were copper or berrylium copper with a tin finish....which eventually wore off or tarnished. Others were copper, others were brass. Getting the same connectivity was important. Keep one type of terminal.

Liek regular sized female terminals that you find in your fuse block....with age, repeated plugging and unplugging and heat....you notice occasionally that one of these female terminals must be unplugged...crimped slightly with a pliers....to get a tight fit. Same exact problem with the D-jet 2.5mm terminal. That....and the fact that the tin coating wears off of teh male pins in various components.

These things caused the vast majority of poor running an poor tunability with D-jet.

To make a usable and better harness from scratch, take a snippet of your wire down to an electronics house and ask them for one of teh same gauge and stranding. This is not so easy as it sounds. Tell them you want a hogh heat jacketing...as high as they can get and still be reasonable...and oxygen free if possible.

Why?...all oxygen free wire does is remove small quantities of iron that are present during normal copper wire manufacturing. It makes the resistance lowre at a very small almost immeasurable fraction. It will have no real difference in the measurable resistance of the system....resistance wise that is.
When measuring under load however...there is a difference. This is more in the realm of potential.

The only real reason to use oxygen free wire is that it will allow you to make all 23-25 wires in D-jet....the same gauge with no ill effects.
As Jeff bowlsby found out a few years back while researching harnesses...there are several disticnt wire variations in a D-jet harness. With teh quality of wire available at that point in time...having a variation in one location or another of wire gauge and current carrying potential was important. With oxygen free wire...it is not.

If you wanted to get anal....you could use silver based wire. More expensive measurably lower resistance...must be crimped and sealed even more religiously....and only a small benefit.

So carefully strip all of the insulation from your harness. Leave the plugs on....make sure the wire numbers are marked. Measure the length of all of the wires. Now you know how much to get. Use the gauge from an injector wire for all of the wire.

Get a decent crimper. Paladin tools make one called the 3000 or 3100. I think I have listed the die #'s in several posts...but if you cna't find them let me know i will post them again.

The crimper and dies will set you back about $75-100. Look at Frys electronics on line and you shoul be able to get the crimper frame for about $50.

Personally, I have found that with a small amount of triming with a dremel tool you can use L-jet plugs and terminals on the injectors, the intake air temp sensor...and the triggert points plug.

The L-jet dual cantilever terminal is vastly superior to D-jet terminals...and is the world standard still in use on almost all injection systems. They will set you back about $2-4 for each terminal. Find your plugs in the junkyard from anything from Saabs, Mercedes , BMW. VW audi etc. If you look hard you can find a three prong plug to fit your trigger point plate with a small amount of trimming.

I have not yet found one that fits the TPS....so I simply connected 5 L-jet terminals to their wires...covered them down to their tips with heat shrink...plugg them on...carrfully centerd them..and cast high temp epoxy into the space around them. I used a "C" shaped wire hook cast in at the ends for a handle to pull it out. Be sure to use mold reslease so you can pull it out.
This madea perfect plug. The heats shrink allows a slight amount of flex room for the spring on each terminal. It also makes them weather tight and has excellent strain relief. If your crimps are correct...you should never have to worry about replacing one of those terminals agin. I did the same on the MPS.

One thing that you should do...and this is tedious.....with a selection of dremel parts, picks etc...polish all of the male terminals in all of the components....down to the copper. You want to remove all of teh side rto side striations that was crimped into them. These ridges were necessary for the stock D-jet terminals ...but are a hindrance to L-jet terminals.

Get a few extra terminals. Take care to make sure you get the correct two or three wire terminals where more than one wire is paired on a terminal.

you will need to practice a few crimps to set teh crimper depth and crush hardness up. Get some green or red circuit varnish, various sizes of heat shrink tubing and a small heat gun.

You also want a small sharp stripper. Never crimp a wire into a terminal that has had any strands removed by teh stripper tool....or has gouges on any strands.

On y strip enough insulation to bare the wire for the length of the crimp barrel. You must have insulation where the outer prongs of the terminals are for the strain relief grasping pins. The dies from palladin have correct crushing parts for both strain relief and crimp barrel to do it all in one shot...if you placed the terminal in the tool properly.

They make a benchtop holder for the crimper tool...or you can mount it in a soft jawed vise. You can use it without this...but its much simpler to have a crimper holder...its like a third hand.

So....when the crimper is set properly...you can insert a terminal...hold it properly aligned with all of the parts of the die...close the jaws to the first click...and it holds the terminal about 1/5 crushed in exactly the right spot.
Strip the wire end...usualy to about 1/4 of strip....slip on 1" of heats shrink tube....do not twist teh wires. They msut be ferfectly straight. Trim the ends if necessary with a sharp scissors. Heat the bare wire to about 200F with a the heat gun...slip it into the terminal in the crimper until the insulation butts up against the main barrel. Close the crimper all the way until it springs back open.....brush on green circuit board varnish immediatltl...dry it....slide down the heat shrink tube to just cover the crimp barrel and varnish...shrink it...done.

The ECU end terminals are harder to do.
(a) because outside of a few enterprising souals (I myself have a full set of new unused ones) ...they are unobtanium at any price.

Never fear!

Take all of your old ones....and snip them off the harness with a sharp scissors...right at the crimp. I collect as many of these as I can get from Junkyards.

Heres what to do:
(1) Buy some hemostats so you can hold these rather fragile terminals without damaging them.
(2) Using the gray soft polishing wheels from dremel...at as low a speed as you can....with a steady hand...relaxed....polish/grind away...the barrel part that is crimped around the wire...and the strain relief.
(3) if you do this right.....what you will have is a "tang"....that was full length of the crimp and strain relief....about .045"-.050" wide and .010-.015" thick. This is tedious, It takes time. You will screw a few up. Get some spares from the junkyard. This tang...or spade....will be used to crimp a new barrel onto the terminal.
(4) When you are done with all of the terminals, clean them with alcohol, polish the contact ends by hand, squeeze them together to make sure they have tension on them...and are uniform from terminal to terminal. Spread the mounting tang out so you know it will catch in the plug.
(5) Go to radio shack. Look in their terminal drawers....look for the yellow butt connectors labled "telecom onnectors". When you get them home...make a tool out of a rod to push all of the metal parts out of the yellow vinyl covers . Its the metal connector inside you want. They are very precise.
(6) using a diamond burr and your hemostats to hold each connector widen the hole in one end to have a slip fit for your wires. Polish the fork terminalsjust the little bit it requires to have a snug slip fit into the other end.
(7) Using one of your dies...insert the fork terminals into one end of each metal telecom butt connector....and crimp it hard..then seal it with green varnish. On the other end...repeat the same with the wires. Slide on the heat shrink tube...and shrink it. You now have terminal crimps for the EcU end....that surpass factory quality.

There is a lot more little detail you can get into on this.....like jaketing...other techniques I have used....but this will get you started. Ray

[JSMskater]

I want to make one from scratch, and I have a NOS "FI repair kit" that has brand new plastic plugs for the ECU, as well as the little terminals that go inside, but they are already pre-crimped onto strands of wire.

as for the other terminals How hard is it to swtich them over to the L-jet style? more exactly, what must I dremel off for them to fit?

[raygreenwood]

If you have the repair kit for the ECU end...that is excellent. Not quite as good as crimping new terminals onto brand new wire.....but as good or better than what came from the factory. When you connect the repair kit ECU connector, make sure that all of the new terminal end wires are exactly the same length. Use teh telecome butt connectors, varnish and a very good crimper just like I described and you will have no trouble.

If you look at an L-jet connector....turn it toward you and look at the female connectors inside. What you see within this plug is an extended rectangular piece inside that holds the two terminals...that reaches into the injector spigot to plug onto the male terminals. The Flange or shield around the outside is simply the latching mechanism that allows the plug body to lock onto the injector.

There are numerous small variations in L-jet plugs. For the most part I find that cutting that outer shield wall back to just about 1.5-2.0 mm above the gasket that is inside of the plug.....is all that is needed. The L-jet plug...internally....is basically the same size as teh inside of a D-jet injector plug area. Its just shaped a little differently. The pin spacing is the same. By trimming the outer shield down you can just push the L-jet plug into the D-jet injector until the gasket seats. Done.
For the most part, these feit very very tightly. Ray