kjurkic

Howdy all from the great white north.

I have managed to get my recently purchased '80 928 back home through the nastiest spring weather the west coast of BC has had in a looong time. I keep hearing about this "global warming" BS, but we certainly aren't seeing any of that here.

I have been searching the forums for some ideas about getting my 928 into the 21st in re to engine management, and I would like to get some hard info on what pieces I need to have on hand so I don't leave the beauty stranded for months.

I want to use the MegaSquirt system to manage the FI, then perhaps to manage spark.

From some other posts, I gather that I should replace the existing fuel rails with ones from a newer (82 up?) shark, so that I can use standard injectors, rather than the rare L - FI's. Is this accurate? Will just the rails be needed, or do I need a stack of bits & pieces?

Apparently there is some debate over whether to use the MAP sensor built in to MS, or some modified AFM or MAF setup. Is there a good reason to NOT use the built-in MAP? It seems this would simplify the whole install, especially of some forced induction is added later.

I guess to simplify, what is the complete minimum list of parts to move from L-jetronic to Megasquirt?

regards all

Ken

BC

You ditch the Barn Door, so you will make new intake pipes for there. You buy a loom with the MS, and they usually use GM sensors. They have different threads, and its a different size. You would probably use Ford's EDIS or something non-porsche like that.

Its not easy to make the later rails work. Maybe get those billet rails and have them machined to work.

Obviously the toothed-wheel issue is a big one and you will need to figure that out.

Use the MAP. It works fine on hundreds of cars for MS.

kjurkic

I saw a post re: toothed wheel; I figured I would likely have to get a trigger system mounted on a front crank pulley - it seems there was no clear way of using existing components for this.

I guess I haven't been reading enough posts yet - barn door? Is that the air filter housing?

thx
Ken

BC

Your L-Jet air meter is called a Barn Door for its archaic simplicity.
You would ditch it for the MAP sensor, which stands, as you know for Mass air PRESSURE, which means you will also install (where there was none before) an AIT, Air INTAKE Temp. I put it on the front vac line on the spider.

MS now can read most wheels. If you can find an 86 flywheel, it has 60-2 teeth. That way you can install the sensor where it usually goes at the top if the bell housing.

Lizard928

MAP = Manifold Absolute Pressure

86 flywheel has a 100-1 toothed ring, 87+ have 60-2

BC

You are correct.

BC

I don't know why I said that. I think MS can handle the 100-1 now.

PorKen

Doesn't matter. The '80 doesn't have a spot for the reference sensor, anyway.

BC

Yes, but it can be drilled at the specific location needed.

kjurkic

So, if am understanding this correctly, I would need to change the flywheel on my '80 for the inductive timing pickup? Seems that it would be easier/cheaper to get one mounted up front on crank pulley...

Parts list so far:
custom fuel rails w/adapters for Porsche delivery lines
8 or more injectors stolen from unattended V8 ford(s)
Either:
1. 87 up flywheel <OR>
2. 100:1 or 60:2 (or some var.) crank pulley trigger system
MS kit or MSII kit
various GM sensors needed by MS
Econo size tylenol

anything else?

thanks
Ken

BC

For what we need, the MSI or MSII will work very well. Resolution is supposed to be higher on MSII? Lizard?

I DON'T think it is easier to mount the timing wheel on the front. There just isn't much room, and I stared at that area for WEEKS before I came up with my ingenious idea to mount it on the smooth flywheel of the 84 cars. It works great and looks like stock.

Lizard928

the MSII has a faster brain with alot more resolution, both will work.

as to the timing/pickup ring, if you do not have the hole in the block for the sensor right now, then mount one on the crank pulley at the front. However if you do this, get a 36-1 toothed ring from a ford, this way you can run EDIS instead of your stock ign setup and have fully controlled ign as well.

I dont see why you couldnt use the stock injectors as well.

if you wish to just have the MS control fuel then all you need to do is make an adapter from the L jet DME brain, to the MS brain, no need for a new harness, as well most of the stock sensors should work with either MS or MSII.

I have a MSII V3.0 sitting here at home, just waiting to install.

BC

With MSII and the VBs, can't you circumvent the EDIS?

kjurkic

hmmm.....stock sensors and no wiring harness hacks....that sounds much better for a first-time shot at updates.

I should point out that there is no dyno anywhere close to where I live, so all setup would need to been done strictly with O2 & seat-o'-pants meter.

I could always change over the rails/injectors later. It was my understanding that this is desirable as the L-injectors are hard to find/expensive; is that correct?

Sorry for the ignorance: VB? for ignition?

so now to date I have choices:

1 - just get MSII, and make adapter to Porsche brain connector; use stock sensors. Learn to tinker with this before going farther.

2 - Jump in head first with custom rails/new injectors/pickup ring/GM sensors. Better for long-term optimization + spark control. perhaps even Sequential FI?

3 - I recall reading somewhere about adapting modern GM SEFI system; has anyone here done that? How complicated compared to MS?

Sorry about all the q's - I don't mind the work of tinkering, but I hate pausing a project while I track down some overlooked but essential part. I want to get a box full of all the parts I need for this BEFORE I disconnect a single wire.

Lizard - do you plan your install soon?

thanks for all the info

Ken

BC

I think using the old stuff coud lead to wiring difficulty due to age and brittleness.