MPFI swap? - Second Generation Forum

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MPFI swap?
Wednesday, August 03, 2005 1:09 PM
hey guys i have a 90 4 banger cavy as my winter beater and i was lookin at doing the MPFI swap but im jsut wondering if theres a how-to somewhere?or does anyone have a lsit of parts needed?i know i would need the head,exhaust manifold,MPFI manifold,TB,and perhaps a bigger fuel pump?,would i need anything else?also would gas mileage increase at all with this setup?also what years car i grab parts from?

FDP 62MM TB, FFP Performance Chip, FFP Underdrive Pully, WAI, Hi Flow Cat, 2.5" Catback, Functional Ram Air Hood, Centerforce Dual Friction Clutch

Re: MPFI swap?
Wednesday, August 03, 2005 4:13 PM
This is from CavGT:

> first off i found out that the 2.0 and 2.2's use the
> same head gaskets
> from 1987-1993 and the exhaust manifolds have the
> same bolt pattern from
> 87-96. so what that means is that you do have to
> get a cylinder head
> from a 92-93 MPFI 2.2 and the complete intake
> manifold as well. but
> since the cylinder head and exhaust all have the
> same bolt pattern as a
> 92-93 2.2 then this swap will work on 87-91 2.0/2.2
> cars. the reason
> you have to change out the cylinder head is that the
> MPFI head has
> provisions for the injectors but the older heads do
> not. because you
> would be getting a new/used cylinder head it is
> always a good idea to
> have it "warmed over" or just looked at while it is
> out. look at my
> site for info on head work for more info. when you
> get the cylinder
> head and intake make sure you also grab fuel lines,
> barb fittings that
> are designed to connect 2 fuel lines together(have
> to get these from an
> auto parts store), complete fuel rail assembly(if it
> has been taken off
> the intake), all sensors(snip and take the female
> side of the fuel
> injector harness that would otherwise stay with the
> donor car , more
> info on that later), fuel pump( i got mine from a 90
> 3.1 so i can do
> many upgrades in the future without having to swap
> pumps again), valve
> cover, intake hoses including airbox, throttle
> cable,and go ahead and
> take all the nuts and bolts that you can find.
> after you have all these parts together you will
> want to have plenty of
> time that you can perform the swap without having to
> be in a hurry.
> tear the top part of the motor apart, but first
> disconnect the battery.
> take off the alterantor, pulley tensioner, and
> disconnect the power
> steering pump but don't disconnect the lines just
> sit it to the side.
> also disconnect the radiator hoses and drain the
> fluid till it is below
> the level of the head by about 2 inches. take off
> the box that hoks to
> the right side of the motor that houses the
> thermostat and egr valve.
> from there go underneath the car and disconnect all
> the hoses and clamps
> that connect to the cylinder head and intake. it is
> easier if you can
> take the throttle body and intake manifold off in
> seperate pieces. at
> this point i cut my fuel lines leaving about 4
> inches of rubber hose
> past the master cylinder on each one. disonnect the
> exhaust manifold
> from the head as well. you don't have to remove the
> exhaust manifold
> from the car, but it does help if you do(i didn't
> but wish i did once or
> twice). the cylinder head was a pain to take off.
> i broke a 15mm
> socket and an extension trying to break the bolts
> free! but yours might
> be easier.
> once the cylinder head is off, you need to clean up
> the mating surface
> real good. it is also a good idea at this point to
> look real close at
> the motor. any carbon in the cylinders should be
> cleaned up, and i you
> have scored cylinder walls then it is time for a
> complete rebuild. but
> if everything is a ok then you can proceed with the
> install. installing
> everything is just he opposite of removal, your just
> putting differant
> parts on. now the sensors all use the same plugs so
> you don't have to
> worry about cutting and splicing accept for one set
> of wires. that is
> the injector wires. that is why i told you to get
> the female end of the
> injector harness. the color codes are the same on
> the wires so just
> snip, match up the colors and solder the new wire
> on. you will also
> have to find a new place to mount your IAT sensor.
> i extended the wire
> for the sensor and mounted it in the driver side
> fender well underneath
> the headlight assembly. now the fuel lines you get
> the barb fittings
> that you purchased and with hose clamps, join the ew
> hoses with the old
> ones. the big hose goes to the left side of the
> fuel rail and the small
> hose goes to the fuel pressure regulator. from this
> point you want to
> go ahead and start assembling everythng together.
> NOTE: don't be like
> me and try to reuse gaskets on the fuel lines. go
> ahead and purchase
> new gaskets for everything. it is also a good idea
> to replace the
> sensors and injectors(i didn't and that is probably
> one of the reasons
> why the car is running real rough).
> one of the last things i did was replace the fuel
> pump. a good word of
> advice here is to run the car until the fuel tank is
> completely empty.
> mine still had about 2 gallons in it which added
> about 12 pounds to the
> weight of the tank.
> now here are the down sides to doing this swap.
> since the TBI computer
> was not designed to power 4 injectors, you do run
> the risk of burning up
> the injector driver under low voltage
> conditions(i.e. real cold weather
> or a bad battery) and the car will run a little on
> the rich side. this
> is not a problem for me because i don't have to
> worry about emmisions
> testing and my Cav is not my primary mode of
> transportation. not only
> that but because of all the other mods i have done
> to my car, this
> should actually give me more power in the higher rpm
> area.
> on another note,(to protect my ass) i have not
> driven the car on the
> road as of yet so i can not give any guarentees of
> what this swap will
> or won't do with your particular setup. however on
> my setup with all of
> my mods i am expecting about a 20-30hp and 10-15ft
> lb increase over
> stock.

You need parts from a 92-93 car. And it's best to swap over harnesses/computers from the engine as well, but CavGT said he didn't and his car just runs a little rich.

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Re: MPFI swap?
Wednesday, August 03, 2005 8:08 PM
Having just done the swap myself, I agree a lot of the above information is good. The only thing I will add is that you can use a head from a 92-95. If you really felt like it, you could even cut the runners out of an 87-91 head for the injectors also.

My car runs rich at low RPMs too, but fuel mileage is up considerably. When I get some extra time I plan to look into swapping ECMs or whatever it'll take to make the car run "right". It has pretty good power though for a beater.

Re: MPFI swap?
Thursday, August 04, 2005 9:31 AM
Some more advice:

The resistance of one tbi injector is the same as the resistance of 4 high impedance pfi injectors. The ecm's injector driver will do just fine.

Modifying the stock mpfi fuel rpessure regulator to be adjustable, or replacing the stock part with an adjustable afpr would allow you to slightly lower fuel pressure and bring fuel delivery closer to correct.

If you find a 94 2.2 to get your donor parts from you'll notice that there are 3 wires at the injector harness connector instead of 2. I believe they are red, blue, and green. For this swap the blue and green wires can be connected together.

If you have an automatic transmission, you'll probably want to get the detent cable between the transmission and throttle body, too.

Believe it or not, you can use the head from the 96 and 97 cars, also. But the injector harness wiring is different.

When connecting the rubber lines, it's a good idea to use 2 hose clamps on each 1/2 of the connector. The increased pressure of the mpfi system (43 psi vs 12) should be treated with a little more caution.

Good luck.
Re: MPFI swap?
Thursday, August 04, 2005 4:47 PM
thanks guys
it is automatic and would u happen to ahve pics of this detent cable or describe waht it is?also can i just swap in the MPFI ECM or woulld i ahve to change wiring harnesses?

FDP 62MM TB, FFP Performance Chip, FFP Underdrive Pully, WAI, Hi Flow Cat, 2.5" Catback, Functional Ram Air Hood, Centerforce Dual Friction Clutch
Re: MPFI swap?
Friday, August 05, 2005 3:59 AM
I've thought about the mpfi ecm vs tbi. I think the fuel for the tbi might be closer, but it's probably a toss up. The mpfi ecm will be programmed for a slightly larger engine, which will also make it run rich. You will need to change or modify the wiring harness to use the newer ecm.

The "detent cable" is also known as a "kickdown cable." Connects from trans to throttle linkage.

Re: MPFI swap?
Tuesday, August 09, 2005 6:21 PM
<<sniff sniff>>>

I'm so proud!!

<<sniff sniff>>>

I never thought this info would still be going around after all these years(it was back in 97 or 98 when I originally did this and wrote the how-to). It makes me happy to see you guys coming up with ways to improve on this swap!! Thanx!!


91 Cav "GT"<-- R.I.P.
91 Cavalier Wagonstein - Turbocharged wagon goodness
You can take my rifle when you pry it from my cold dead hands.

Re: MPFI swap?
Wednesday, September 16, 2015 6:59 PM
im getting ready to do this on my 90. i can get parts off a 95. is that ok?
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