Hi, I have a 89 civic wagon D15b1 with the DPFI throttle body. I have read as many postings on this as topic possible and no two are the same. Can anyone tell me with certitude the difference between mine and the b2. And would swapping to the b2 help increase my performance slightly. I had read the choke butterfly only opens halfway on my unit and all the way on the b2. Is this the only difference? Can I modify mine? Clearly, the the car will never have guts, But all I want is a little more off the line especially with the A/C on. That is when it is truly a dog. I am not looking to swap to MPFI right now (Daily Driver) just looking for more pep. Some techs say the cams are different on the b2, others say not. What gives? Thanks, Ricky

 

Ya the two are different but both suck in terms of performance. Just not enough fuel and air to make any power. MPFI is your best bet to increase power but your not interested at the moment. Until then just enjoy the AC while going slow and enjoying the sights. I am not trying to be a jerk but I had dpfi and swapped mpfi...huge difference!!

 

Th tandem valve plate and the intake v-plate mod make the intake noisier, but you won't feel any off the line performance like you are looking for.

 

i have a D15B1 as well. not much power. i took out the restrictor plate in the intake funnel, added a short ram intake, 4-1 header, installed E3 spark plugs, and replaced the injectors. throttle response at idle improved noticeably, struggled SLIGHTLY less than usual on the hills, but still sucks. and sadly that's about everything you can do to a DPFI that i know of. I'm doing an MPFI swap here in the next week or two in my hatch.

 

Thanks for your reply.I can;t believe the Japanese built such a dog. I would consider a MPFI swap, But I have read so many conflicting threads on Ecu change out. Is it a simple swap from the original Ecu to the b2 engine Ecu and MPFI hard parts. Or is it a wiring nightmare as suggested? Also, I understand the cams in the b2 have slightly more lift and duration than the b1. Can I just swap out the cam rocker assembly or is this a head removal? I have a low mileage wagon with no issues (oil burning) and it would be easier to change cams and get out. It seems that there is no consensus out there with all these smart people. Can anyone simplify this with a laser beam focus? Thanks, Rick

 

They didn't build a dog really, they built an engine for great economy.

The MPFI conversion is only a nightmare to people that make it a nightmare. If you take a little time upfront and understand the reasoning behind the steps taken, then it becomes really easy.
Some of the diagrams and write-ups people create contain way too much info and make it really confusing.

Change out the intake manifold and distributor.
Move two wires at the ECU because they now go to a different sensor in the distributor.
Add two wires at ECU to fire the additional 2 injectors.
Wire in the resistor pack to supply power to the new injectors.
Add 2 wires for a distributor sensor to handle the additional 2 injectors.
Extend the wires for the TPS an EACV so you can plug them in.
Reverse the outer wires in the TPS plug because DFPI version rotates the opposite direction than MPFI.
Plug in MPFI ECU and drive off into the sunset

 

Thanks 4drEF for your reply. A few years ago I owned an 89 prelude Si 5spd. It was a fast car and good on gas. This DPFI wagon I have is slow and not good on gas. I have resolved myself to do a MPFI swap in the future. Being that I have a auto trans, Is the Ecu I'm looking for have to be from a Si with AT? I would assume so, but not positive. The junkyards here in CA. have few Honda's, and usually picked clean. Is there any advantage in changing out the cam/rocker assembly from an Si? Also, will I have any smog issues if I do the swap? Thanks, Rick

 

pm6 are all manual. you would need to find a PS9 ECU

 

The smog issue that you I'll have is that you will potentially fail the visual inspection because you are not allowed to change out intake manifolds in CA.
If you did a full engine swap to a D16A6 then you can get it bar inspected and have a legal MPFI swap.

The biggest limiting factor is going to be your automatic trans. I would just leave the DPFI alone. No performance to be found with that slush box in there.