So I was gettin all of my stuff together for my MPFI on my 89 DX sedan. for the hell of it, I went ahead and tried the pm6 while keeping everything else stock. I hit fuel cutoff at 3k. Is this normal when replacing a pm5 with a pm6 and not changing out the other MPFI components (dizzy, intake mani) to have the fuel cutoff at 3k or did I buy a bad ECU

 

the reason why you are at fuel cut off at 3k without the necessary mpfi components but just a dpfi with a mpfi pm6 ecu is because the ecu needs communication with the extra sensors that are added in the swap. THose sensors are in the distributor which your dpfi dizzy doesnt have, crank position sensor for example. THerefore the ecu doesnt get the signal and the result is the same as if you had all the components for mpfi, but the dizzy and/or sensors inside it failed, resulting in the ecu essentially <U>going into limp mode</U>. THis term is used to refer to a very low fuel cutoff/revlimiter(3000-3500 rpm usually) that is engaged when the ecu doesnt have proper communication with one or more of the required sensors.

That should answer it for ya

 

I was thinking it had to do with the original DPFI components with an ECU setup for MPFI. Thanks much for the help man.

 

Wrong ECU for the motor. of course it's not going to work...

 

For a cheap fix, just find a d16z6 89-91 CRX head, or even a d16y8 head out of a 92-95 Civic and get that VTEC wired up. Both heads are direct swaps onto any D-series deck. I'm doing a similar build, and it aint failed yet. Just use that pm6 ECU, and find the dizzy , and IM and your golden. Oh yeah can't forget the corresponding engine wiring harness and VTEC solenoid. All these should mostly come together, except for the wiring harness.

 

Sorry, not trying to do a mini-me. Just want MPFI on my DD d16y7. Plus the MPFI will already be wired up for my future B-series swap. Thanks for the help