I want to get rid of the ESA system on my 87 D100 and replace it with a two barrel and vacuum advance distributor.I would like to get rid of the charcoal canister also.My question is:is all I have to do is replace these parts and unplug the ESA computer or is it connected to the ECU somehow? Will I have to do anything to the air pump or is it not controlled by the ESA computer.What else is involved in this conversion?

slaubaugh@aol.com

The ESA and ECU are currently combined in the same "black box" on your truck. The air pump is mechanical and belt driven, however the air swithching valve is connected to the ESA computer and send the air from the air pump "upstream" wiht cold engine and "downstream" with warm engine. My air pump got lost when I had to replace the water pump.

The ESA computer has many inputs (temp sensors, curb idle ground switch, vacuum transducer, don't remember what all else). Also many outputs to control ignition timing, lockup torque converter, EGR system, Air pump switch valve, maybe more. On a California truck you can add the O2 sensor and feedback carburetor system.

The ESA computer does have some unique advance curves built into it. For one, with a cold engine it ADVANCES the timing upon DECREASING manifold vacuum. Exactly the opposite of a conventional vacuum advance pod. This greatly enhances cold engine driveability.

If you disconnect the ESA computer and use a conventional distrubutor you will have to build your own wire harness for the ECU. Most of the other stuff will be inoperative with out the ESA comptuer.

I"ve been thinking about doing the same as you but I have an auto transmission with lockup torque converter that is controlled by the ESA computer. I've not came up with a plan to keep the lockup torque converter operating automaticaly.

I like to keep the charcoal canister hooked up and working. It catches all the gasoline vapors from the fuel tank and carburetor and routes them into the engine to be burned when it is running. Saves us from having to breath all those hydrocarbon vapors.

The info I presented is not real specific. The factory service manual does a good job of explaining much of the ESA system and what it does. Also I found a book by OTC (Owatana Tool Company) that went into very explicit detail about the ESA system. It was one of their books about electronic engine systems. Unfortunatley I don't have access to that book anymore, I found it at a vo-tech auto shop and the school has since shut down the auto program.


cfield@ll.net