Hello everyone, I am currently on my 3rd ECU and have no clue what is causing my ecu to go bad. There is no CEL or any lights. The MIL will go off after 2 seconds.

First ECU(Bought the car like this) - no start, no spark, CEL - P0700, P0758, P1753, P1758, P1794
Second ECU - Start - ran for a couple of hours - then no spark (replace NEW DIZZY still no spark)
Third ECU - Start - ran for approx 20 mins - then started to misfire and flooded engine with fuel - injectors were getting constant ground
Fourth ECU - Start and Run only on idle

Some of the items that have been checked
- Replaced Distributor
- Replaced Sparkplug + NGK WIres
- Tried 3 different Main Relay
- Tested alternator - Passed

Ive tested some other small items but has anyone ever ran into this issue? What other test should I do?

 

Poor grounding issue. (main grounds,ECU grounds)

Poor battery or charging system issues.

The above are common culprits in repeat ECU failures.

 

I am using a good and new battery, alternator has been tested good and reading 13.9v. With car running the battery is constant at 14.2 volts.

All ground have been checked(VC, Thermostat, and Transmission)

If I am correct, the only ground for the ECU would be at the Thermostat housing?

 

How were the grounds checked? Were they volt drop checked?
What is the alternator diode readings?
What is the ohmic reading of the negative battery cable?

I dont know how many grounds the ECM has. You need to look at a wiring diagram.

Where were the ECUs sourced from?

 

Took off each bolt and cleaned surface with wire brush then checked the continuity from each ground location to the battery. I have not done a volt drop check for each of the connection.
Alternator have not been diode checked and will perform that later on.
I cant remember exactly what the ohmic reading for the negative battery cable but I will double check later on as well.

What do you mean where the ECU sourced from? Like where I bought them? I bought 2 off eBay, one from my buddy and one from a local guy.