Hi All,

I ran a quick search of the forum but nothing obvious came up.

I have a DIYPNP for my 1.8 99 Miata/MX5 I'm hoping to install shortly, I've been reading about the sequential injection upgrade but can't find much info regarding the actual benefits. I understand what it does, but there seems to be conflicting theories on actual benefits.

Is anyone running one and can they vouch for it? Smoother running, improved torque curve, response, mpg, bhp?

The mod can be picked up for around £50 in the UK and to be honest, I've looked at the circuit, it looks like a couple of resistors, a couple of caps and a couple of VND5N07 mosfet transistors (which are about £1 each).

If anyone knows a more competitive European supplier that would also be very much appreciated.

Thanks in advance,

Adam.

 

Here is a summary comparing the two:

Tech Page


In my opinion sequential injection is not worth the effort. But that's just me.

 

It is totally worth the effort, especially since you already have 4 injector channels in the harness on an NB. You shouldn't have to change anything, just solder the add-in board on and jumper up the ECU plug right.

Anything under 4k or so revs will be much much smoother. You'll be able to idle 14.7 without surging. You'll be able to dial back acceleration enrichment, because you won't need as much. You'll basically have fuel injection like your car came with, something of this century.

If you are cheap, you can build it on the proto section for really cheap. The partslist was posted here somewhere before, like $7 bucks in components...

 

I have done a batch-to-sequential conversion on a 1990 model 1.6, using an MS3Pro, so I can speak to this first-hand.

In theory, sequential injection should improve idle stability. I honestly can't say that I noticed this, though of course I didn't have an especially poor idle before doing the conversion.

The effects of batch-vs-sequential at cruise will be extremely minor, and nonexistant under high load.

The primary function of sequential injection is to decrease emissions at idle and light cruise. This should, in turn, cause an improvement in fuel economy, however the potential magnitude of said improvement is extremely small.

 

Thanks Guys, that's exactly what I was looking for.

I had read that article before which is really good but I still wasn't convinced of the actual real life scenario benefits.

It's not that I'm cheap (well I am a little haha) but I just hate paying £50 (about $75) when I know the components cost less than a tenth of that.

If I could source a schematic or parts list I would definitely install it (probably build it on some veroboard), does anyone know where I can find either? I've already sourcesld the mosfet transistors.

Thanks again, really appreciate the replies.

Adam.

 

Hi guys,

My impatience led me to do something I should have done before, Google.

I found the schematic, might be useful if anyone else is in the same boat. Such a simple circuit.



Thanks,

Adam.

 

1. Those who seem to be in the know, suggest, unlike the article, to inject against a closed valve, not an open one. I don't know what OEM does.
2. Another thing not addressed in the article is that, when batch firing, the timing is different for each cylinder, whereas, from a cylinder's point of view, they are the same for each one with sequential.
3. If the EAE math and theory is anywhere near correct, then there is almost always a working puddle, save perhaps during deceleration or other high vacuum situation.
4. I think it would take a lot of work / dyno time / to be able to discern where the ideal injection timing should be over the entire 3D map.
5. My car and MS3 came with sequential, so I don't have to make the choice.
6. Maybe, after I get cold starts, and all the other major parameters adjusted, I'll think about fooling with the timing table, but likely, I'll not fool with it and just drive the car.

 

perhaps useful?

 

Thanks, y8s

The table suggests that, assuming you set for END of PULSE, that the table on a fixed intake (pre-01, MSM) should be all the same number.

Note, that the number in the MS table is *BTDC related to compression / power stroke, hence the number is 360* for TDC of Exhaust / Intake.

Some early discussion here: msExtra

Also, interesting how they (I presume Mazda) is showing 83% Duty Cycle. Looks more like 40% Duty Cycle by normal definitions, but then again, it is a diagram, and how would you wrap it back around?

 

I made that diagram so that can account for a lot of it.

 

Wow, thanks guys that's fantastic.

I made my circuit on some veroboard today. As soon as the alternator circuit arrives I'll install the ECU and let you know if it starts (fingers crossed!).

Thanks,

Adam.

 

Adam,

Were you able to get this circuit working? I would like to see how you wired it. I can't really use the 10 pin header that comes with the DIY one because I'm already using it for wideband wiring.

 

you built a wideband into the protoboard in a DIYPNP?

 

Not exactly. I'm using the 12V, Gnd, and Sensor ground from the 10pin header to power my wideband. They go to the DB15 to make the wiring much easier to keep neat.

I had an idea to make my own board for sequential and fabricate some makeshift standoffs. But then doing more research lead to using the proto area like others have done. This seems like the better alternative.

 

i misread. you can still use it, but you'd have to first desolder your wires and then resolder them once the module is in place.