First of all, I've read what I could find on the DPFI > MPFI swap already. I couldn't find this info in there, so please forgive me if I missed it....

I'm trying to determine exactly how the DPFI > MPFI conversion will affect the performance and operating characteristics of the engine in my '88 DX. By that I mean that I need to know if the conversion changes where the engine seems to work most efficiently and/or make it's best torque. If anybody has any hard dyno numbers that would be great, but even seat of the pants impressions will move me in the right direction.

The reason I'm asking is because I'm building a mpg car, and I need to know this before I decide what transmission gearing to choose and wether or not to do the swap. I may eventually add a VX engine, so having the car converted to MPFI already would ease that process, but if it's going to hurt me in the meantime or if it means that I can't put in my hybrid trans, it might not be worthwhile....

 

Well I dont have dyno numbers not even really seat of the pants figures cause when I did the swap I went from an auto DX to a manual Si and not just an MPFI swap.

However there are a few things I can help with like it wont affect your hybrid tranny you will be able to still use that and yes it would be easier to go to the VX motor however there are complete conversion harnesses to go from obd0 DX to obd1 VX well Z6 but same difference just different type of vtec. I dont think it will hurt your MPG's but you might be better off going with an HF MPFI swap then since those were built for MPG's in the firsrt place.

But in all reality I think if you are planning a complete VX motor swap you would be better off just saving your money for that motor rather than the money and time to swap over to the MPFI THEN to the VX.

Hope that helps.

 

Well in theory it'll help, and the HF *made for econ* had EFI.

They only way I can see you keeping same or losing milage would be due to a more aggressive fuel curve on the ECU, that could be avoided by running an MPFI ecu from a HF.

 

I guess I should be a bit more descriptive...

Currently, my stock DX seems to get the best FE in the 3200-3500 rpm range, so I'm looking at adding a DX trans with an HF final drive. With my tires, that puts me at about 3200 in 4th gear (for normal highway driving) at 75, and about 2600 in 5th gear (for light load situations like downhill).

If the MPFI raises the rpm that th engine is most efficient at, then it will throw everything off and probably reduce my MPG.

Also, regarding the HF computer; since the HF isn't a 16V engine, I doubt that the fuel and spark curves would be correct or yield the same FE. I probably wouldn't risk it without testimonials from other people who have already gone down that road. From what I've heard, a non-vtec 92-95 DX ecu is a better choice in terms of finding maps that will match my existing engine.

 

I don't think it will really be that big of a difference. the mpfi swap isn't going to move the engines highest efficiency RPM more than +-500 rpm..

As far as computers go, you should just get a chipped pm6 and a wideband, and have someone tune it for max. efficiency. You may not find a lot of maps tuned for what you are looking for. Most modified maps I have seen atleast are for turbo and na cars who's goals are not fuel mileage.

Realistically, doing an mpfi swap on a DX probably needs a retune because the cam profile between what the PM6 was created for and what is actually in the DX are different. most people around here, me included, would just run the pm6 stock, but it is not optimal for fuel efficiency. The 92-95 sohc non-vtec ecu would be closer to what you need, but you could just copy the 92-95 map into the pm6 map and use it instead, which will be less drama from a wiring perspective.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sanimalp &raquo;</TD></TR><TR><TD CLASS="quote">.....you could just copy the 92-95 map into the pm6 map and use it instead, which will be less drama from a wiring perspective. </TD></TR></TABLE>

That has some potential as well. I'm pretty new to the Honda world though. What would it take to be able to tune the PM6? (Some aftermerket equipment and a laptop I assume, but a few specific recommendations would be nice). Also, where could I come up with the stock 92-95 maps? That's the kind of thing that I wouldn't expect to find just posted up online, but maybe I'm wrong....

 

here is a giant list of most of the maps, as well as the accompanying .bin code.. http://mycomputerninja.com/~jo....html

as for tuning the pm6, if you already have one and can solder, you can buy the parts for about $30 to allow you to reprogram the computer at will, and for about $200 you can buy what you need to set up a wideband and tune it. for more information on that, you can go to http://forum.pgmfi.org, or just read up here http://mycomputerninja.com/~jo....html, and also on H-T https://honda-tech.com/zeroforum/124



Modified by sanimalp at 1:11 PM 9/2/2008

 

Cool, thanks for all the info. My lunch break just ended, so I'll have to peruse the links later tonight.

I'm the least technical of a family of EE's, so I'm actually a step or two ahead of the average bear in terms of my electronic skills... plus I have good people to fall back on should I get into trouble. I'll check my spare ecu to see if it's a pm6 or not... If it is, then it sounds like I'm in the clear though. I know I can get all the hardware I need for the swap for just a few bucks, and my labor comes pretty cheap, so the conversion may be a worthwhile endeavor even if it doesn't work out as planned and I have to go back to to DPFI....

 

Hmph, so my spare ecu is a PM5... Before I spend a bunch of time researching, can I still hack it, and is it worth it, or should I just pick up a PM6 off ebay or somewhere else?

 

Pick up a PM6-A09 or something like that, i think they have a chip socket.

 

Right, I just found basically the same thing on the PGMFI forum. The PM5 can't really be chipped, so I'll just use it when I first drop my manual trans in (I picked it up for exactly that reason), then find a PM6 for when/if I do the MPFI swap.

Now I just need to do some extra reading and figure out if I want to tweak the stock maps for better MPG.... It's can be so hard to just leave things alone....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Radim &raquo;</TD></TR><TR><TD CLASS="quote">Pick up a PM6-A09 or something like that, i think they have a chip socket.</TD></TR></TABLE>
Hey, can anybody confirm this? I've been digging on and off and haven't found any info about wether the -A09 has a chip socket or not.... I'm decidedly lazy so if I can avoid all the extra soldering and find a unit with a socket already built in, I'd rather go that route.

Any ecu hackers out there care to lend a hand?

 

To my knowledge none of the honda ecus come WITH a socket they all have to have one put in. I think what it is is that the pm6 CAN be chipped where as other obd0 ecu's cant.

 

Sorry, i was a bit wrong on what i said but here is the truth.


The 90-91 Version (PM6-A09 & PM6-L09 are the US version codes) come from the 90-91 EX Civic and CRX Si have the external Eeprom and are easily chippable. -HMT

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Vinceg99 &raquo;</TD></TR><TR><TD CLASS="quote">To my knowledge none of the honda ecus come WITH a socket they all have to have one put in. I think what it is is that the pm6 CAN be chipped where as other obd0 ecu's cant.</TD></TR></TABLE>

that is correct. You will have to remove the existing chip on the pm6, and replace the chip with a socket that allows you to switch chips whenever you want easily.


Modified by sanimalp at 4:49 PM 9/2/2008

 

OK, thanks all. Now at least I won't be disappointed with what I get. Is it just the -A09 and -L09 ecus, or do all of the PM6 ecus going to have the external eprom?

 

Only those two, which is why they are worth more than the other PM6s.