Something cool about dual point injection!

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theB16tegguy

Senior Member
I don't know if any of you already know this but for those of you who don't... If you own a 88-91 dx civic or crx you've been missing out on something. Check it out,
open the top of your dual point cover
look down in the hole with the screen over it
now press the throttle cable all the way(as if you were flooring it.

notice anything weird about the butterfly plate??
yea.. it doesn't open all the way does it?
A HONDA mechanic showed me this and he said that there is a little piece that you have to bend and then it will open all the way. not sure exactly what.(I'll get pics soon)

Also theres a gasket where the throttle body connects to the manifold.
It is extremly restrictive!!! you have to buy a new gasket and cut it to the actual bore of the manifold. I think he said it was so restrictive he could'nt have droped a quarter in there! I'll be correcting this problem saturday and let you know how it goes

Boy was HONDA thinking economy or what.. restrictive gasket and butterfly?? no wonder my shit bogs all the time.

hope this helps DX owners.
 
Well for one it let's way more air in. Like 50% or so. I mean this is really restrictive. I'm correcting all this saturday and will get pics and feedback. The mechanics at honda who don't have si's do this and beat si's daily so I'm told.
 
yes way, I'll show you saturday. The butterfly only opens but like 75% and then the gasket is half the size of the throttle body. now that I think about it. It should be a pin that's in the way of the throttle.
 
If this works then I'll be the happiest person with DPFI. Finally, I can begin to hybrid the D16 intakes from the 99 EK DPFI. (One airbox that sits ontop of the intake)


I'll do this sunday. Thanks for the info


-> Steve
 
:werd: If this is the case, then I can get some more power out of my step bro's dpfi zc car. That would great, no wiring hassle to get power, just cutting gasket, and bending a pin.
 
:unsure: Parents threw a fast one on me today and I had to go to a party(family thing) they assured me that nothing like this will happen tommorow. so pics and procedure steps will be up tommorow. Sorry guys... I gotta move out of there. sorry again. It'll be up tommorrow.
 
Take pics of before and after. If the article is written good, B will probally post it in the article section.
 
hey man, we could be the dual-port bros! hahaha
thats some interesting stuff though keep us posted
My mini-me dual-port is only a few more hours of overtime away! yaha
 
There is a restrictor plate inside the DX throttle body that can be removed to allow for more airflow... is this what you're reffering to?

I've removed it from an 89 DX sedan once just to see what it would do & it killed the torque & didn't really do much for power that I could feel... it did have a tiny little vtec-like effect, where you could feel a slight "kick" at around 3500rpms, but I'm seriously talking a slight kick. I'd say for the loss of low end it wasn't worth removing.

This was performed on an entirely stock motor that I swapped into a car just to sell, so who knows if it could be more useful on a car with more modifications. I'm assuming that the plate was engineered to increase low end throttle response, & that is it's sole purpose.

mep
 
Ok so I took everything off of my CRX DPFI and There was nothing like the mechanic told me. Both butterflies opened up and the gasket was the same size as the bore of the intake manifold...... So then I called my buddy up to see if they maybe only did it on civic's.(he has an 89 sedan) his was exactly the same.(I'm thinking WTF!) So I've come to 1 to 3 conclusions.... either it's only on the civic standard, just the hatch, or it's just randomly put on certain DPFI manifolds. I need for those of you who have DPFI to do some investigating for me. First take off your DPFI top cover. Have someone floor the gas. look at both butterflies and see whether or not they open all the way vertical. Okay, now take off your throttle body(easy, four bolts) and see if there is a plastic gasket over another gasket that is smaller in diameter. This is what should have restricted the air flow. Thanks, I didn't mean to be a disapointment, but I now would like to know which cars honda did this on?? Was it random? or was it an aftermarket option? Help me figure this out! thanks and sorry for the bad news.
 
my firends 90 crx dx had a metal plate infront of, or behind(i cant remeber), the throttle body that he removed but the gasket was fine... oh and for reference there was no real noticeable power gains... seeing as the motor didnt make much to start with...
 
Since my old motor from my 91 dx was sitting in the garage, I decided to go in today and take a look. Sorry to dissapoint you theB16tegguy, but mine was exactly as you described your motor. The gasket was the same size, the butterflies opened vertical and nothing was like the mechanic told you. Oh well, it got my lazy butt into the garage for a nice day's work anyways :lol: .
 
well there on one of the dpfi manifolds because i watched the guy do it so i guess its only on the std civic hatch cause thats what he had
 
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