Q's about using N/A distributor with Turbo motor and ECU

[Guest bastaad525]

Was trying to find some details on this but didn't have any luck. I'm just curious about the details and how to's for this setup. I'm having some odd ignition timing problems that are proving very difficult to track down, and am thinking I should take control of the ignition advance away from the ECU completely. I'm also 99% sure I'm going to be switching to Megasquirt soon, so I'm thinking that would be a good time to switch over to an N/A mechanical advance distributor

 

Couple questions for you guys who run this setup:

 

What year n/a dizzy is preferable?

 

Do you run it with the vacuum advance connected?

 

If you guys are using a year dizzy that has the ignition module on the side, does this need to be wired to something or is it just left disconnected? what do you wire it to?

 

What do you set the initial timing at? The stock 20-24 degrees recommended for the turbo? What about the maximum advance? I know an N/A dizzy when set to about 10 degrees BTDC, will advance to a total of about 36... so if you set it to 20 for turbo it's like 46 degrees total advance... isn't that way too high? If so how do you guys keep it from advancing so much?

[randy 77zt]

iif you use a 75-78 distributor the mag pickup will directly fire a msd box.you could get a msd box with a boost timing retard built in .it will need a vacuem line from intake manifold runto it.run the vacuem advance.it will go back to no advance under boost.at cruise under no boost you should get 32 to 35 degrees total advance at 3000 rpm or so.under boost it should retard to 20 to 24 degrees btdc.the zx distributor will fire msd or others using points wire.watch out for locked up mechanical advance on used distributors.there are some plastic parts that break under the pick up plate and lock up the mechanical advance mechanism.use a hand vacuem pump and a good timing light with advance dial on back.

[Guest bastaad525]

I'm already running an MSD 6A... I was looking at the seperate boost retard unit. So I can run any of the 280z-280zx n/a dizzies, correct? If I can run a ZX unit then I already know how to wire that to the MSD (man it was a pain in the ass figuring that out the first time).

 

Now here's my next question. I'm looking at buying a Megasquirt system from another member, so if I hand fuel management over to that, and am running the MSD to an N/A dizzy, do I need to retain the factory turbo ECU at all? I'm trying to get rid of it 100% if I can. But something tells me I'll have to keep the factory ECU in there for some reason or another... to send a signal for spark maybe? As it stands the MSD gets it's signal from the ECU... so I guess it'd have to stay in use?

 

I'm really excited about swapping over to the MS system in my car but there's so little info on these boards on how to hook them up right.

[SleeperZ]

 

Now here's my next question. I'm looking at buying a Megasquirt system from another member' date=' so if I hand fuel management over to that, and am running the MSD to an N/A dizzy, do I need to retain the factory turbo ECU at all? I'm trying to get rid of it 100% if I can. But something tells me I'll have to keep the factory ECU in there for some reason or another... to send a signal for spark maybe? As it stands the MSD gets it's signal from the ECU... so I guess it'd have to stay in use?[/quote']

 

If you use MS for fuel and an n/a dizzy/MSD for spark, there is no use for the ECU at all.

[Guest bastaad525]

where will the MSD get it's trigger signal from?

[SleeperZ]

where will the MSD get it's trigger signal from?

 

The n/a distributor.

[mobythevan]

BTW, the megasquirt'nspark guys are upgrading their code to make it easier to set up the trigger signal from the distributor. No more goofy trigger requirement, this should easily allow us to use the turbo dizzy (83 in my case) and have the rpm vs map advance table. You still need an ignition box like MSD to handle dwell and drive the coil. Just throwing that out as another option. With that setup you don't want advance on your dizzy, you want a fixed signal at all rpm to the MS.

[Guest bastaad525]

Sleeper - okay let me see if I have this right. I'll hook up the MS for fuel and completely remove the nissan ecu. Then I'll install, lets just say, an '80 n/a dizzy with the module on the side, and my msd. Now, I remember from my n/a motor, that I had to remove the module from the dizzy, and the two wires from inside the dizzy I then connected to the purple and green magnetic pickup wires on the msd box. So I'll wire that the same way... and that would be the signal I need right? That leaves the red and white wires which hook up to the wires that in stock form, go to the coil. Now, the instructions state that if you run the magnetic pickup connections, leave the white wire disconnected. The red wire has to be hooked up either way... here is where I get lost. The way I have my MSD installed now, the red wire goes to the wire from the ECU that would normally go onto the coil +, but if I remove the ECU, then what do I connect that wire too? I know before I put the turbo motor, the stock wiring harness had it's own wire that went to the coil positive (that wire is still present and the end that used to connect to the coil is just dangling, I dont know if the other end of the wire is still connected to whatever it's supposed to connect to), but obviously didn't come from any ecu (it had su carbs) so where else can I get that signal from?

 

Or waaaaaaaaaait a second... is that wire (black with white stripe, I believe) just the switched power source?? THAT would make sense! So I should be able to hook the red wire to any switched power source right?? Then it's all hooked up and ready to go?

 

that still leaves the more important questions though, what about the advance at idle and the advance curve? Do I set the N/A dizzy to 20* at idle like with the stock turbo dizzy? Will I have to modify the N/A dizzy to keep it from advancing as much as it normally does or is it's maximum mechanical advance fine on the turbo motor?

[SleeperZ]

Or waaaaaaaaaait a second... is that wire (black with white stripe' date=' I believe) just the switched power source?? THAT would make sense! So I should be able to hook the red wire to any switched power source right?? Then it's all hooked up and ready to go?

 

that still leaves the more important questions though, what about the advance at idle and the advance curve? Do I set the N/A dizzy to 20* at idle like with the stock turbo dizzy? Will I have to modify the N/A dizzy to keep it from advancing as much as it normally does or is it's maximum mechanical advance fine on the turbo motor?[/quote']

 

You are way ahead of me. I'm speaking in a theoretical sense. I'm sure there is a way to wire the n/a reluctor to trigger an MSD, which will control the coil with the appropriate dwell and current. The initial advance and advance curve is set with the distributor.

 

The initial advance will likely be different with the n/a dizzy than the turbo dizzy, because the ECU, once the initial reference is set, can move the advance where it is programmed to do it. A mechanically advanced distributor needs to be set to the least advance at the idle rpm. What I notice with the turbo ECU setup is the initial advance is set to 20*, and once off idle, the advance moves. You will not find a n/a dizzy ever doing that. My suggestion is to set the n/a dizzy to what the n/a motor likes, and use a boost retard on the MSD to tune the total advance under boost.

[z-ya]

I'm triggering a Megasquirt with the "-" terminal of a stock coil, driven by an NA distributor/ignition modlule. Needed a slight mod to the pickup circuit (added one capacitor), but it works fine.

 

Pete

[yo2001]

May be I'm not getting this right but N/A dizzy or turbo Dizzy got nothing to do with MSD 6A from my experience. I've used in on both dizzy without worrying about what triggers and what not.

 

78 dizzy got a good advance curve. I think 16 deg. with initial 20 deg, you can get 32 deg total and with BTM set at 1 deg retard per 1 psi. I had it running 10 psi no prb with N/A ECU and FMU.

[SleeperZ]

May be I'm not getting this right but N/A dizzy or turbo Dizzy got nothing to do with MSD 6A from my experience. I've used in on both dizzy without worrying about what triggers and what not.

 

78 dizzy got a good advance curve. I think 16 deg. with initial 20 deg' date=' you can get 32 deg total and with BTM set at 1 deg retard per 1 psi. I had it running 10 psi no prb with N/A ECU and FMU.[/quote']

 

No, Yo, I believe you are right. The MSD is nothing but an ignition amplifier. Give it a signal, and it fires a spark. Advance must be controlled elsewhere.

[Bernardd]

How does the N/A setup control dwell? Is it in the ignition module? If it is, it would be simple to tear out the module and make the megaspark'n'squirt work. I have no idea how the wiring goes in the module but you could make a custom chopper wheel with proper sized windows, adjust the dizzy so the signal goes high at the proper time (I forget what the spec is) and goes low 5 degrees before tdc, and send out the signal to the ignition module which can send it to the transistor and voila, we have ignition. Does this make sense? I've got the parts sitting in the garage if someone can confirm this might work. I've got two megasquirts that can be installed in short order.

 

Please bear in mind that I haven't slept for three days due to someone in the family loosing her teddy bear.

Bernard

[Jersey]

I've been following this topic as well since i'm interested in using the MS, using my MSD 6A and the '78 dizzy that's installed on my N/A L28 if it'll work. The only thing i can contribute right now is, Bernardd, i feel for you and your daughter My daughter lost her snuggy in toys-r-us one day and i went back that night and ransacked the entire store, and found it! Good luck and hope it shows up, for her AND for you! haha. Ok, back to the topic Sorry, punchy @ 1:45am

[Guest bastaad525]

Sleeper - Hmmm I know my N/A motor liked about 8* BTDC at idle... but damn... that's low compared to the turbo motors setting... I have a feeling it would be sluggish as hell off idle if I set it that low. I dont know if anyone has ever gotten the n/a dizzy module to work directly with the MSD... I mean I spent a LONG time scouring here and zcar.com and couldn't find anything. Then I just took the module out and wired the two internal wires from the dizzy to the green and purple magnetic pickup wires of the MSD and it fired right up and ran GREAT. This was in my '72 with SU's, but when I had that same motor/dizzy in my ZX, I got the signal differently, from the red and white wires, connected to wires from the ECU.... the same way I have it hooked up now with the turbo dizzy. It makes sense now... that white wire off the msd will only work with an ECU fired signal, otherwise with no ecu present you need a magnetic triggered signal... LOL sorry I'm sure this is making no sense at all

 

Yo2001 - you're right... I know it doesn't make a difference as to what dizzy... they will both work with the msd. I was thinking more for the trigger signal but then sleeper z clarified it for me and I realized n/a dizzy gets it's signal from inside, it doesn't need the ecu to control it. You did hit on the main thing I needed to know... so with N/A dizzy I will need the Boost Timing Retard thing for my MSD. I figured I would... Thank you for clarifying about the timing settings So... '78 n/a, set to 20* BTDC at idle, and with the Boost Retard set to 1* per 1psi, is that all correct? And Yo, do you run the vacuum advance connected?

[yo2001]

No vaccum advance, it'll blow out the vacuum pod out as soon as you hit about 12psi

 

If you run 20 initial with 16 deg mech. advance, you'll be running 36 total, that's plainty advance I would think

[Guest bastaad525]

ugh... I'd like to have the vacuum advance hooked up for better part throttle off boost driveability... you say it will blow out if it hits 12psi... does it matter that I'm only running 10? I'd like to run it if I can...

 

Now, you said that the stock n/a distributor only has 16 degrees of mechanical advance or will I have to alter it to get that curve?

 

Or will I just need the MSD spark retard? Man I'm running out of open ports on my intake manifold for this stuff.... how much is the spark retard anyways?

[yo2001]

I didn't have problem with no vacuum advance on mine. I got my BTM still here, I'll sell it to cheap.

[Guest bastaad525]

the boost retard module? that will hook up to my 6A right? How much you want for it Yo?

[yo2001]

I'll sell it to you for $100 shipped. email me at yo2001@bellsouth.net

 

O, and yes it hooka up to 6A