atreju

Dear all

I have a 1987 Chevy Caprice Brougham with the 305 Stock engine on it. The Engine is Carbureted with the electronic carburetor.

I have several issues and I am currently checking all electronic wirings and functions.

I noticed that the car still runs with the ECM disconnected. Is that normal? I thought the engine won't start and run because of the electronic ignition control (no vaacuum controlled distributor).

Is that normal that the engine starts and runs without ECM or is something really wrong with the cabling of the car?

Kind regards
Atreju

RBob

iTrader: (1)

It is normal for the engine to run without the ECM. The distributor is in bypass mode, same as during cranking or with the 4-wire connector open (to set timing).

There may or may not be advance built into the ICM. If there is can usually feel it when it kicks in.

RBob.

atreju

Thank you for the answer! That would explain the rough idle and jerking while driving with constant speed - I have changed almost everything on the car, it nearly the last thing.
I bought the car without ECM and did not think about that this one could be broken (I thought the car wouldnt run with a broken or missing ECM).

Is there a ECM Pinout for 1228079 ECM? So i can check Ground and Power distribution on the ECM Plug? Just to make sure the ECM has correct grounding and power.

Thank you very much for your answers!

Kind regards
Atreju

RBob

iTrader: (1)

Over on the DIY_PROM board:

https://www.thirdgen.org/forums/diy-...-diagrams.html

RBob.

atreju

Thank you for that - I measured all values and everything seems to be good. I hope the new ECM will resolve my issue.