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DPFI to MPFI Conversion

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wiring harness

Postby RedRyder » Wed May 04, 2005 5:56 pm

anybody wants a harness for any car whether its dx duel point go to this website for all you need. just search any search engine for "rywire" He does good work and is cheap.
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DPFI to MPFI Conversion

Postby 91_hatch » Tue Jan 10, 2006 2:08 am

i am in the process of doing a dpfi to mpfi on my 91 hatch and im still confused on the wiring, but i found a 20 page how-to on fourthgenhatch.com. it shows you how to do it all without converting the wiring harness, you can use the dx harness, but you have to switch around some pins at the ECU plugs, it saves some cutting and taping and you have to run some extra wires, but its the best desciption of the swap ive found on the web and sounds like the easiest.
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MPFI: notes on wiring instructions

Postby ElbertR » Tue Mar 14, 2006 12:46 pm

Just completed the MPFI swap on my 91 STD HB.

Have some comments on the instructions found in the first post of this thread and many other simular instructions found on the web.

- If your new MPFI manifold has a FITV (fast idle thermal valve) and you want to hook this up, you CANNOT use the pin from the B2 ECU connector and use it for something else. B2 is the ECU wire for the FITV. My advise is to get a couple of 88-91 Civic/CRX ECU connectors from a junk yard and take the extra pins you need out of these connectors.

- None of the MPFI instructions I found on the web mention anything about this difference in wiring between a DPFI and MPFI car: the Purge cut-off solenoid valve is wired differently!

This valve sits on the firewall and has 2 wires going into it.

DPFI: Green (-) and Black/Yellow (+). Black/Yellow is wired to the main relay and fuse nr. 14. Green is a direct connection to the ECU.

MPFI: Green (+) and Black (-). Green is a direct connection to the ECU and Black is a ground wire.

If you don't change the wiring for this valve you have 2 wires with +12V hooked up to the valve which will result in an ECU error code with 20 flashes.

To fix it simply cut the yellow/black wire about 3-4 inches from the valve and take the wire from the valve and ground the it to the firewall. There is a hole in the firewall right by the valve where you can screw a bolt in to hold the wire.

Finding the reason for the ECU error 20 and this difference in wiring took me quite some time. Hope this information will save you from the same fate.
1991 STD CIVIC HB: D15B1 with MPFI Swap and 5-Speed DX Tranny, Power locks with Remote, Power Windows, Power Mirrors, Remote trunk popper, JDM arm rest and middle console. Hatch Swap: Put on a DX hatch with wiper & washer (both working)
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DPFI to MPFI Conversion

Postby clubphatpower » Sun May 21, 2006 11:31 pm

what if you have the 91 si and all the wireing but you have and engine with the dpfi on it can you just install the mpfi and not do any wireing..

heres the story I have a 91 si with mpfi and I blow the motor and i have a chance to get a fully rebuilt motor out of a 89 civic dx with dpfi and wish to swap engines and just need info on it..

I also read that I can install the cam out of the 91 si into the 89 motor.. can that happen too.. thanks all and ps i can find the info on the search thers lots of info on if I'm doing the dpfi swap but i already have the mpfi setup I just wha to swap engings thats all but i need to know this info so that i can buy the car.. thanks and have a great day
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DPFI to MPFI Conversion

Postby ElbertR » Mon May 22, 2006 12:29 am

"clubphatpower" wrote:what if you have the 91 si and all the wireing but you have and engine with the dpfi on it can you just install the mpfi and not do any wireing..

heres the story I have a 91 si with mpfi and I blow the motor and i have a chance to get a fully rebuilt motor out of a 89 civic dx with dpfi and wish to swap engines and just need info on it..

I also read that I can install the cam out of the 91 si into the 89 motor.. can that happen too.. thanks all and ps i can find the info on the search thers lots of info on if I'm doing the dpfi swap but i already have the mpfi setup I just wha to swap engings thats all but i need to know this info so that i can buy the car.. thanks and have a great day


Just strip the DPFI parts of your new engine, put on the MPFI parts from your old engine (Intake, trottle body, fuel rail with injectors and the distributor) and you are good to go. This would be the best way to go, otherwise you would have to rewire your car for DPFI. Nobody will recommend that.

I would buy a new gasket for the MPFI intake from any autoparts store.

Yes you can swap the cam from your SI to the DX engine.
1991 STD CIVIC HB: D15B1 with MPFI Swap and 5-Speed DX Tranny, Power locks with Remote, Power Windows, Power Mirrors, Remote trunk popper, JDM arm rest and middle console. Hatch Swap: Put on a DX hatch with wiper & washer (both working)
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DPFI to MPFI Conversion

Postby clubphatpower » Mon May 22, 2006 1:27 am

thank you Im going to get the car now and swap everything over.. :lol:



"ElbertR" wrote:
"clubphatpower" wrote:what if you have the 91 si and all the wireing but you have and engine with the dpfi on it can you just install the mpfi and not do any wireing..

heres the story I have a 91 si with mpfi and I blow the motor and i have a chance to get a fully rebuilt motor out of a 89 civic dx with dpfi and wish to swap engines and just need info on it..

I also read that I can install the cam out of the 91 si into the 89 motor.. can that happen too.. thanks all and ps i can find the info on the search thers lots of info on if I'm doing the dpfi swap but i already have the mpfi setup I just wha to swap engings thats all but i need to know this info so that i can buy the car.. thanks and have a great day


Just strip the DPFI parts of your new engine, put on the MPFI parts from your old engine (Intake, trottle body, fuel rail with injectors and the distributor) and you are good to go. This would be the best way to go, otherwise you would have to rewire your car for DPFI. Nobody will recommend that.

I would buy a new gasket for the MPFI intake from any autoparts store.

Yes you can swap the cam from your SI to the DX engine.
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DPFI to MPFI Conversion

Postby superme » Sun Jul 09, 2006 1:48 am

would converting DPFI into a MPFI give you much more performance? im not switching my engine, and ive heard you can convert to MPFI without any parts, just rewiring, is this true?
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DPFI to MPFI Conversion

Postby chezuki » Sun Jul 09, 2006 1:51 am

MPFI is definately better performance. As for your second question, Have you even read this thread that you are posting in?
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DPFI to MPFI Conversion

Postby Parnelly » Sun Jul 09, 2006 1:33 pm

LOL. So true. Read this thread then ask yourself that second question.
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DPFI to MPFI Conversion

Postby Empty_Spiral513 » Sat Dec 16, 2006 6:33 am

I got a MPFI manifold from my friends 90 SI when he wrecked it, its got everything with it. I was thinking about putting it on my hatch until i have the money for my swap. Should i just put it on and connect all the vaccume lines and such, and then follow the instructions to wire the 2 extra injectors in the ECU? will that work properly?
"there aint nothing your gona do to make that rice burner look good"
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DPFI to MPFI Conversion

Postby ElbertR » Sun Dec 17, 2006 12:38 am

"Empty_Spiral513" wrote:I got a MPFI manifold from my friends 90 SI when he wrecked it, its got everything with it. I was thinking about putting it on my hatch until i have the money for my swap. Should i just put it on and connect all the vaccume lines and such, and then follow the instructions to wire the 2 extra injectors in the ECU? will that work properly?


Good idea to do the MPFI swap before a engine swap.

You will need a few extra parts besides the manifold (trottle body, fuel rail with injectors, distributor, injector resistor, mpfi ECU) but your friends SI should have all the parts.

Remember there are 4 extra wires to run to the engine bay. 2 for the extra injectors and 2 extra for the CPS in the SI distributor.
1991 STD CIVIC HB: D15B1 with MPFI Swap and 5-Speed DX Tranny, Power locks with Remote, Power Windows, Power Mirrors, Remote trunk popper, JDM arm rest and middle console. Hatch Swap: Put on a DX hatch with wiper & washer (both working)
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DPFI to MPFI Conversion

Postby gumby » Tue Feb 27, 2007 11:42 pm

so to swap a b16 in to a dx you would have to do this then what? to you need to get a obd0 to obd1 harness or what?
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DPFI to MPFI Conversion

Postby siR in progress » Tue Feb 27, 2007 11:46 pm

if your engine is OBD1 then you have to because our cars is OBD-0 or Pre-OBD as some people say
rywire has good harnesses for it its all that dude does out of his house
the conversion really isnt all that taxing
the harness is really straight forward and easy
siR anyone?
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DPFI to MPFI Conversion

Postby gumby » Wed Feb 28, 2007 11:24 pm

thanks :D
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DPFI to MPFI Conversion

Postby el_jelly » Sat Mar 31, 2007 12:49 am

Although this has been for a while another topic emerged on the dpfi-mpfi conversion: http://www.civic4g.com/forum/viewtopic.php?t=7390

and

another one: http://www.civic4g.com/forum/viewtopic.php?t=9737

:wink:
Last edited by el_jelly on Tue Mar 24, 2009 7:06 am, edited 1 time in total.
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Where most of the questions are already answered > Engine swap guide, FAQs and Index thread
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