Guide to MPI Conversion?

[fr335tyl3r]

Hey all,

Been looking through posts and instead of blowing all my money on a massive VR4 conversion I might try to do some smaller stuff myself and learn a lot about engines and cars in the process. So basically what should I look at to do an MPI conversion cause from the sounds of things this would be a good thing to get started on for future expansion (and i was going to change the ECU over anyway).

I have an ECU in mind already that can control multi coil injection so dont worry about ECU suggestions for now. Just basically what parts should I be looking at and what is the hit up in terms of price?

What benefits can be had from putting on an XF throttle body rather than a standard L300 which sounds like an easier fit?

Thanks in Advance

[SpidersWeb]

The XF throttle body is just much larger, and can flow more, but you'd need some custom work to fit the thing.

Best MPI setup I've seen is by using the Sonata manifold, as its more similar in design to the VR4 model except it fits the SOHC head, and the throttle body points to the front of the car - so no more crossover pipe from your intercooler.

There was a poll done a long time ago on here, with Sonata vs L300, and it had pictures and information on both. Could be worth a gander.

[Chris 83JA]

I'm in the middle of one now.
So far I've bought an L300 manifold, complete with fuel rail, pressure regulator, tps, throttle body for $200 from a light commercial wrecker.
I found 4 good condition 2nd hand EVO3 510cc injectors for $290.
Have yet to get an O2 sensor and air temp sensor, though these aren't required.
Other than that there's a little bit of mucking around to make various things fit, but not much at all from what I gather. I'll be documenting the whole process and will make a quick 'idiots guide to the mpi conversion', which deeks can maybe put up on the site.

How soon are you going to do it? It'll be a few weeks until I can get mine in and make up the guide.

[fr335tyl3r]

I'm just working out costs really at the moment...i am going to do it but need to take care of rust and rego before i worry about makin it go fast :D

but yeh, the guide sounds great...suits me perfectly ;)


p.s. im only an idiot when it comes to cars :D

[Chris 83JA]

I'm an idiot too, that's why i'm making the guide.
The only way you learn is by pulling things apart, breaking them more than you mean to, then eventually getting it all back together again.

[fr335tyl3r]

The XF throttle body is just much larger, and can flow more, but you'd need some custom work to fit the thing.
.

What sort of custom work is involved? What sort of extra cost would I be looking at? I think im heading towards a 2.4Sonata TB with an L300 dizzy and intake manifold at the moment unless someone can point me in the direction of something both cost effective and better in performance :D

[CussCuss]

im not sure anyone with 2.5" piping or smaller should be considering an xf falcon tb, the L300 one is 2.5" wich flows plenty.

At the moment i have a complete l300 manifold ($200), ecu, but no injectors (well i do have l300 ones) so they are next.

Things that i can see that need doing
- New banjo fitting for the fuel supply
- Mucking around with the injector wires (i only have 1/2 of the plug)

and probably a couple of other things but i havnt looked fully into it

[Cookiemonster]

Internal diameter of the L300 throttle body is 50mm (1.96")

[Chris 83JA]

Things that i can see that need doing
- New banjo fitting for the fuel supply
- Mucking around with the injector wires (i only have 1/2 of the plug)

and probably a couple of other things but i havnt looked fully into it

accelerator bracket
heater hoses
crossover pipe (if no intercooler, or cooler piping)


anyone know what the l300 injectors flow at? :D

[CussCuss]

50mm? didnt look like it came in that much, i measuread at the inlet pipe, might have to fint an xf tb and adapt.
hrm crap have to redo hoses again.

[Barney]

I run a XF throttle body with 2.5 inch intercooler piping.

One thing I have found with such a large Throttle body, very little depression on the accelerator is needed to get the engine to rev. The problem with this is when trying to drive out of a corner the car comes on boost hard with very little depression on the accelerator. This makes it hard during driving events to get the power down with out getting it sideawys. This is not a problem on the road however

ASHLY

[fr335tyl3r]

Ultimate noob question:

What do you mean when you refer to a coil pack? or coil packs? The guy that is making my ECU for me and monitoring system suggested that I go for a coilpack setup that is similar to what my uni racing team uses (same ECU) and it will be fired in wasted spark configuration.

He sed new dual outlet coils will knock me back around $75 a piece and ill need two of them. Anyone care to give me explanation as to what this goes? He said with the coil packs I wouldnt need a dizzy just an igniter of some type? Lol im so confused.

[Chryzla]

i dunno, i dont have a ECU, but i have a multispark Cranecams ignition system?

just means the lower the revs the more time the sparkplug sparks to make sure it burns all the fuel.

[SpidersWeb]

Ok here we go:

Standard Starion Ignition:

One Coil
The distributor decides which spark plug to fire. Timing adjustment is controlled by the vac advance/retard unit.

Dual Posted Coils x 2
An ignitor/ECU tells the coils to fire directly, and it fires two spark plugs at a time. This is called 'wasted spark'. So one coil per pair of spark plugs. This does allow the ECU to advance or retard ignition timing (instead of using a distributor and vac advance unit).
The only thing your L300 distributor does now, is work as a pickup for the ECU.

Sequential Multi-Coil or Direct Fire
Same as above, but with two more coils, which means no wasted spark. The coils are normally smaller, because they only need to fire one spark plug per engine cycle each.

Coil pack=coils in a group, that your spark plug leads plug directly in to

Feel free to correct any errors guys, but thats what I picked up when I was doing my little ECU/Ignition research a while ago.

You do not need a distributor if you have a cam angle sensor with base and pickup signals. You dont. So you need an L300 dizzy to make these signals (thats the whole point of the L300 dizzy - the optical pickup).

Also an ignitor is just a box that tells the coils to fire when it gets a signal from the ECU. I dont quite get this, Im chosing Microtech because it has the ignitors built in to the ignition drives (apparently), but I guess you could use your existing ignitor, (the gold box behind the battery) and one more.

[Fuel]

Ok here we go:

Standard Starion Ignition:

One Coil
The distributor decides which two spark plugs to fire, and yes spark plugs do fire when not needed (e.g. when cylinder 3 is firing, cylinder 1 (I think) gets a spark also). This is known as wasted spark.

Dual Posted Coils x 2
An ignitor/ECU tells the coils to fire directly, and it fires two spark plugs at a time. So one coil per pair of spark plugs. This is also 'wasted spark', but allows the ECU to advance or retard ignition timing (instead of using a distributor and vac advance unit).
The only thing your L300 distributor does now, is work as a pickup for the ECU.

Sequential Multi-Coil or Direct Fire
Same as above, but with two more coils, which means no wasted spark. The coils are normally smaller, because they only need to fire one spark plug per engine cycle each.

Coil pack=coils in a group, that your spark plug leads plug directly in to

Feel free to correct any errors guys, but thats what I picked up when I was doing my little ECU/Ignition research a while ago.

You do not need a distributor if you have a cam angle sensor with base and pickup signals. You dont. So you need an L300 dizzy to make these signals (thats the whole point of the L300 dizzy - the optical pickup).

Also an ignitor is just a box that tells the coils to fire when it gets a signal from the ECU. I dont quite get this, Im chosing Microtech because it has the ignitors built in to the ignition drives (apparently), but I guess you could use your existing ignitor, (the gold box behind the battery) and one more.

Can you please describe in detail, how one distributor and one coil can fire two spark plugs at the same time.