1984 Mazda Rx7 (p15 - normal service is resumed)

'You've been driving all day, doing nothing, you really are such a waste of time'
'No honey, you don't get it, I was busy mapping the electronic fuel injection on my rotary turbocharged engine, it's a totally different thing!'
'Oh I didn't know, I'm sorry, you are so manly when you work on your car'

WIN

That's an interesting system Phil I think for now I'll stick to idle speed by hand and cable, or I'd probably got for a proper idle control valve with closed loop control for that OEM style rock steady idle.

The flooding shouldn't be a problem when I've actually tuned it in! haha.

Well I've had a frustrating few days.

I've been chasing problems with my Megasquirt for days and felt like I was getting nowhere. Today I cracked it and realised that basically my coils were shot. Dropped in a pair of old coils on the leading plugs* and she fired right up! Best get ordering a new set of coils then

Been out for a 20 minute drive and it works! It's gonna need lots of tuning time and somewhere along the line I've lost my interior lights and drivers electric window but still, I drove it!

And she sounds so wild on the throttle bodies, screams like no car I've experienced! I shall get a video clip up once I've got a few of the problems ironed out and she's running better!

* On the Mazda rotary each rotors has two spark plugs, leading and trailing. The leading does most of the 'work', whilst the trailing help with emissions and add just a few % power up the top but gives better low end drivability. The engine will run ok on just the leading plugs

Cheers Qwerty

After a fairly manic week, I had an afternoon off today to sort some of my snagging issues out.

First off my interior lighting issues turned out to be a fuse and the electric window I'd forgotten to plug back in :oops: So they were easy fixes!

Next up was to raise the rear suspension a little. Having dropped it ~25mm when I moved the suspension mounts it was now nose high and I didn't want to lower the front any more as it would really start to compromise the amount of travel I've got. Only too a few minutes and now she's sitting really nice and flat, trim heights of 310mm all round.



Whilst I've been working this week I have managed to take her out for a drive over a few evenings and made a little progress with the tuning. With a bit of help from the datalogs I discovered a couple of issues. I was having a few sync issues between the CAS and megasquirt even after re-routing the cable, so I changed a smoothing capacitors value and thats done the job. I also finished wiring in the old choke magnet to megasquirt so my high idle is semi automatic! This means she's spent all week looking like this:



So I spent a hour or so tidying up then finished mounting the Megaview. It's not as clean and neat and tidy an install as I'd hoped but for now it's functional.



In the radio space is the Megaview with its function buttons that gives me data readouts from all the main ecu sensors and outputs, it also allows me to make basic changes to the MAP, kinda changes that mean I can limp home if needs be it doesn't replace the laptop for tuning. Below that in the old cubby hole is the oil temp and the oxygen sensor reset and status lamp.

Finally all the tuning I've done this week has been pretty much wasted as I only just realised the throttle stop is fouling the throttle cable so IO was only hitting about 85% throttle. :roll:



So I sorted that. Roll on 100% throttle!

I'm hoping to sort my trailing coils in the next couple of days so then tuning can begin properly, for now I'm just trying to get it somewhere near across the whole rev & load range, as there were some rather large holes in my base map!

One thing that is interesting is that I've been doing some ignition timing research and found a number of sources showing the supposedly very good base map from the Apexi Power FC for turbo II and FDs and their n/a section of the map looks something like this. (ignore the blue and red numbers thats telling me whats recently changed and it's gone wild because I've loaded a completely new map in!)



Where looking mainly at the 100% load row (what) the timing increases fairly linearly right up to 39 degrees BTDC at 7500 rpm. Now the maps I've seen most Megasquirt guys use look more like a direct mapping of the timing the distributer would produce, where the advance at 100% load levels off at around 24-28 degrees at 4000 rpm and increases no more to the red line.



I've had a play with both and the Power FC style map does feel better, but I'm cautious about running that much advance and for the moment till I sort the trailing coils for a decent set it's just wasting my time to do any more on it. I will be sure to get dyno comparisons of the two base ignition maps though when I got her on the rollers.

I think you need to go wash your mouth out after using the S word I only changed the rear suspension for more negative travel for better handling, better s****e is just a by product

As for the throttle plate screws, I was thinking the same thing when looking at that photo!

Been out for some more of a drive and playing with the spark tables, the Power FC style table definitely feels better at low revs, but it feels no better at 4-6k and at 7k it doesn't feel as good.

So I've gone back to the dizzy based map and given it some extra advance at around 50-75% load and 1000-3000 rpm so the shape matches that of the PFC and it feels pretty good for now. I shall leave it alone now till I'm on the rollers with better trailing coils.

I was going to say that it's awesome to see it coming along nicely, that the pics are lovely but then I realised you didn't put a link to the video and got me badly, oh yes badly frustrated.

Love the sound of a rotary. This car is so, so right.

Cheers guys

Epic cool car mate - my hat is taken off to you - LOVE IT!