The title is a little misleading. I'm replacing the ECU,along with the TPI, fuel pump, exhaust system, heads, and cam.

I've been eyeballing C4's for years. I actually bought a junk 92 that ran back around COVID. It was going to be a vette kart. When I got into it, it had issues with the opti-spark and at least one head gasket. So, I sold it for what I had in it.

Last summer I bought this 85. It's a manual car with a richmond 6 speed installed. I brought it home and started to learn what needed to be fixed on it. A short incomplete list:
Starter not engaging properly intermittently
AC system / and heater fan inop
Windshield wiper system inop
Cruise control system inop



I removed and replaced the starter about 10 times until I finally figured out that some of the parts weren't properly tightened or were broken and were effecting the crank cycle. Replaced parts and tightened properly made all the difference. Removed the starter interrupt switch on the clutch too.

Cruise control and the AC / fan system were linked due to vacuum. Hooked all that back up and boom. They both work. AC still needs charged.

Wiper motor is saved for another day.

While driving the car, I'd get numerous check engine lights that I had to hunt down and troubleshoot. The FSM and this website have saved my bacon numerous times. Faults have included: MAF sensor, Knock Sensor, EGR. If the MAF sensor fault illuminated, the car would go into a limp mode. I quickly figured out that all these faults are easily cleared by turning the car off and the turning it back on. I tried working through these faults to figure out a solution to each. As I learned about each, I found out that these are some of the typical issues with this year/era C4. I started looking at what it would take to reprogram the ECU to remove these issues.
After weighing all the options to this issue, I decided to install an EFI system made by Aces EFI. I bought the Aces EFI Wild Card II system. It includes the intake, throttle body, sensors, injectors, harness, ecu, power distribution module (complicated fuse block), and more.
I'm going to document the work in this thread. Current state of things:






I've learned quite a bit as I take this thing apart. One thing I was surprised to learn was that the engine is a replacement. I had made all my plans, calculations, and purchases off the ASSumption that the motor was the original 1985 L98 with 9-1 compression, 5cc dish forged pistons, 2 bolt main caps. The motor is the targetmaster crate motor with 8-1 compression. The pistons have huge 16cc dishes in them. So, I've had to do some refiguring on the compression. More on that later.

Current goal is to install the ECU, harness, and integrate parts of the old harness still required to run the vehicle.