I have a 1990 automatic tranny 'vert that's an engine and etc donor for a swap, I will be using a 5 speed tranny.

In the interest of keeping my initial costs down, plans are to use the stock wiring harness and ECU. A buddy of mine used a 1986 13B with the stock EGI system ECU in a VW Beetle, for some reason the engine would not run unless he used the stock instrument cluster. I can certainly use the stock cluster if I have to, but I'd prefer not to.

So, does the stock ECU need to see something from the cluster for the engine to run (I'm guessing it would be tach or speed signal or maybe both) and if so is there a workaround?

 

my 88 runs without the cluster hooked up.

 

my 87 TII also ran fine when it was disconnected for a few days during modding

 

Interesting. I'm going to unplug it and see what happens.

My bud had to leave the cluster connected, he just stuck it under the passenger seat and zip tied it in place.

 

If your bud used an S4 cluster with an S5 ecu, engine and harness, that was his mistake. There is a difference between series in regards to the check engine light and how the codes are read. There was also a mid year change from low to high impedance injectors in 87 along with changes in the wiring harness and ecu. The S5 also went to an electronically controlled MOP which is tied into the ecu. If you match the engine year with the ecu and harness, you should be good. If you can't, then I suggest going with a MegaSquirt standalone ecu and harness

The MS is the cheapest standalone on the market and has several advantages besides pricing. It's perfect for us DIY guys, it replaces the brittle 20+ year old wiring, allows for fine tuning and any mods you want to install and the software code is open source with great support. An assembled unit will run around 500 with harness, minus needed sensors, about 1/3 the price of a Haltech

There is a MegaSquirt sub-forum here on the Club or you can read up on it in the main MS forum.

http://www.msefi.com/index.php

 

It's a complete and running car and the engine, harness and ECU will be used in the recipient car as a set. My plans are to start with the stock ECU etc for the swap but I'll be using aftermarket instruments. I also plan to remove as much of the stock engine harness as possible for weight and simplicity reasons but that won't happen until the swapped car starts and runs.

I will probably go TII at a later date and at that point I'll probably go Megasquirt, mostly for ease of tunability.