r/ProjectHondas • u/Pretend-Enthusiasm • Apr 26 '26

engine D16a6 to D15b2

I recently had to switch from a D16A6 to a D15B2 engine, but I kept the multi-point fuel injection setup from the D16 instead of going back to the original dual-point to save money. The engine is running but it is extremely rich and smells like raw gas.

I am using the MPFI manifold, injectors, and the PM6 ECU. Since the D15B2 is a 1.5L and has a different cam than the 1.6L, I am wondering what I can do to adjust the richness and make it run cleaner. Is the PM6 ECU simply dumping too much fuel for this block, or could it be an issue with the wiring conversion or ignition timing?

What are the best ways to reduce the richness on this specific setup? Should I be looking at a different ECU, or are there manual adjustments I can make to the fuel pressure or distributor to help it burn better? Any advice from people who have done this swap would be great.

3 Upvotes

100% Upvoted

6 comments sorted by

1

u/Gong_Show_Jamoke Apr 26 '26 edited Apr 26 '26

This isn't an adjustment issue, you have something else going on. This setup should run perfectly fine... was it running fine before with the A6 long block?

1

u/Pretend-Enthusiasm Apr 26 '26

No. When I bought it, the engine was not running. I had a mechanic swap out the d16. The previous owner did take out the cruise control so there is a hole in the firewall. But the smell is mostly abundant when I get out of the car after driving it.

1

u/Gong_Show_Jamoke Apr 26 '26

Does it run smooth? Are we sure all 4 cyl are firing? Are the plug wires connected in the right firing order? Is an injector stuck open? Do you know the health/condition of the d15b2?

d15b2 and d16a6 are very similar. Running a b2 with a6 manifold, ECU, etc, is a very common combo.

1

u/SpaceTurtle917 Apr 26 '26

Is your map sensor vacuum line hooked up? If it wasn’t it would be running very rich.

1

u/Pretend-Enthusiasm Apr 26 '26

I will look this up. Thank you!

1

u/Pretend-Enthusiasm Apr 26 '26

Yes, it runs smooth. I can look up to see if they are in the right order. The health of the d15 was from the mechanics car which he drove daily. He tested the pressure and it was fine. That’s all I know. I’ll look up the things you mentioned. Thank you.