CHT Wiring to DME on 84 3.2

[Capt J.D.]

Hello Folks, this is my first post so please take it a bit easy if I'm not versed in all procedures.
Anyway, I have an 84 Carrera Coupe 3.2 that has just given up the ghost so to speak. Parked it and next morning a NO GO. Engine cranks beautifully, so have and still am going through the many checklists available on this forum.
I have ordered the three sensors ( speed, reference, and CHT) I have the original CHT single wire so will change that out. However, upon removing the DME side of the CHT wiring I came upon a spliced in (resistor?) Can someone tell me why this thing may have been spliced in there? And when changing out sensor side of CHT with new two wire unit should I remove this (thing)?
The white background in the pics is a piece of cardboard because I have a black on black engine room.
Thanks.

[gregwils]

I'll give you a suggestion, but mostly a free bump. It's anyone's guess why he put a resistor in line. If the car isn't running, I would be inclined to go back to a stock config (no resistor) with a two wire CHT. Hopefully, you'll get more specific advice from others.

There are a number of people on the board with tons of expertise in this area, I can't remember all of them. If they don't respond ischmitz or Grady Clay are certainly two that could give you some direction, but there are lots and lots more.

[Capt J.D.]

Thanks for the reply Greg. I appreciate the advice. My thought is that the single wire CHT may have at one time caused a problem and perhaps they thought that they may have messed up that part of the DME circut, so to perhaps bypass that, they put the resistor inline? I know, it is a wild thought but why would anyone want to mess up a perfectly good wiring system to the DME? Bear in mind that I am in no way, any sort of electronic person, but logical thought is one of my attributes..LOL

[dad911]

It's hard to tell from the pic, but it looks like only one side of the resister is connected? If so, it's not in the circuit, and doing nothing.

[Joe Bob]

Back to the no start. Move the seat forward, put hand on the DME relay, turn on ignition. You should have a click. No click is either a bad relay or no power to the DME.

[Capt J.D.]

dad911 - both wires of the resistor are wired into the same line heading to the DME. (the red/blk). the brown wire, I assume "ground" is intact.
To ALL:
Thus far I have done the following tests:
a) replaced DME Relay - it does click. Second click is discernable. (Original 1984 relay was still in use).
b) replaced ignition coil. proper voltage and readings from terminals. Original coil readings were a little low.
c) replaced rotor. Distributor cap on order to go with new rotor. (Bosch)
d) jumpered fuse to fuel pump in trunk. Fuel pump runs.
e) ICV valve vibrates when ignition is turned on
f) replaced red fuel relay in trunk
g) cleaned fuse contacts in trunk and replaced older looking fuses. (with proper ratings)
h) cleaned all grounds on body.
i) checked and cleaned ground from what appears to be the transmission to the body gound under vehicle. (this appears to be not what is normally seen( two separate small ground wires) so will add a proper ground strap from trans/eng to proper point on tub.
j) cleaned DME wire harness and tested various pins for proper ohms. Pins 25 & 26 are not reading correctly,so have ordered the ref and speed sensor.
k) main battery is good.
l) have never had any start problems before.
Hope this helps anyone who may have some ideas on the no spark no start issue.
Thanks guys.

[Capt J.D.]

Forgot a step.. I did try the spark test with a plug and ground. NO spark

[Tippy]

I feel for you. These Motronic cars without OBD are impossible to figure out.

I'm still trying to figure out mine after months of different tests and throwing money away on good parts.

[Tippy]

Ah, maybe step "J" will get you going.

GL!

[Capt J.D.]

Originally Posted by Tippy

I feel for you. These Motronic cars without OBD are impossible to figure out.

I'm still trying to figure out mine after months of different tests and throwing money away on good parts.

I sort of look as not so much as throwing money away, but investing in "inventory".. LOL.
When all is said and done; and I finally get the vehicle running, I will then reverse the installation of new parts and thus find out what is " used Inventory" and what caused the problem... in theory.
In the meantime, I just hope that our host can keep a supply of good reasonably priced parts.
I have also ordered the Bentley Manual to add to my reference library.

[Tippy]

Yeah, I got 3 good used parts myself on inventory....

[Capt J.D.]

It seems as if I have found a possible answer regarding that resistor.
Various "searches" led to a post regarding "tricking the DME to believe that the CHT was OK". It appears to be the only logical answer. I will be replacing my single wire CHT and the other two sensors as soon as I can get them and the time to do it.
Thanks for the suggestions.