Hello everyone, this last time I have advanced in my project, which is giving me some problems related to engine power. therefore, I decided to consult the group in search of wisdom.

It is an A20A3 engine, (BT says the block) I am not sure if it comes from an accord or a prelude, the car where I installed it is a 1983 prelude. The ecu that I got from a 1986 prelude has the code 37820 PJ0 663. ( This ecu, if I am not mistaken, is different from that of the accord a20a3 motor, because it does not have the outputs for the EGR connection, according to the prelude manual 1985-1986).

I will explain the problem: when the car is stopped and I rev the engine, it does not exceed 6000 rpm, then when I go out on the street and accelerate it, it does not exceed 5000 revolutions and also backfires are heard.

With the help of a strobe lamp, I regulated the advance in the distributor, leaving 15 degrees BTDC (mark that is on the flywheel) and according to the guide in the service manual.

there is no code showing the ecu, there are no vacuum leaks.

I have noticed two things that make me wonder.

1. I don't have the vss signal connected, I don't know if it is related to the lack of power in these motors.

In the service manual of an accors with a20a3 motor, it shows on pin out of the ecu that pin B18 has voltage values ​​between 0V - 3V.
(I do not have the signal because the car cluster is not designed to connect to the ecu).

2. When I checked the timing of the motor, notice that the camshaft sprocket has a little free play, it is not exaggerated, but I feel when releasing the bolt and moving a little movement from one side to the other, and the same happens with the crankshaft sprocket.

With regard to the movement of the pinions, I made several measurements of keys with the intention of supplying the degrees that the pinions moved, but I still get the same result.

Is it because of the vss signal? Or by the ECU?

What does the vss signal do in an obd0 system of an A20A3 engine?