Rexanne!

[Steve-A]

I've been a bit slack with the progress documentation this week, I'm just getting my head down and trying to get it done. My initial deadline of a month is fast approaching and really to meet that deadline I need to be in a position to at least try and start her up over the weekend.

So whats happened over the weekend and into today... I got the fuses and relays wired up in the glove box and the Megasquirt mounted. Wiring will be wrapped and green tape gone once I know it all works!



All sensors are reading sensibly, and the ones I can test without running the car are responding. I had a bit of a scare when I got no crank position signal initially but it was a dirty connector, which was a nice simple fix.

I've still got to wire up my wideband controller, the Megaview and my oil temp gauge. I'd had enough wiring for now anyway so decided to work on the fuel system. First up I got the engine bay side all connected up which was pretty simple.



After lots of thought I've decided to mount the pumps and swirl pot in the spare wheel well. I will make a metal over this and seal it down so I still have a fire wall between me and the fuel system (and it it will reduce the petrol smell in the cabin I guess) but this way the pumps should be safe from the elements and easy to get to for maintenance. I've got everything but the return from the fuel rail connected up here.



While I had the back of the car up in the air I decided to tackle the rear axel. As you can see it doesn't look so shiny after 6 months of use and plenty of salted road action.



I've got two niggles with the rear axel. The first is just cosmetic, with my GAZ coilovers in the rear I've currently got to run with about a 30mm arch gap to give me a sensible amount of negative suspension travel. So I'm going to add an extra mounting point for the coilovers so I can run the same suspension travel but drop the rear of the car down so the arch gap matches the front.

Secondly she's always pulled a bit left, and shortly before I took her off the road I took her to have the suspension alignment checked out. The front was running a bit too much camber, but was essentially ok, the rear axel on the other hand was almost 1/2 a degree out of line, causing my left pulling. I broke out the calculator and dredged the back of my head for some trigonometry knowledge and decided that one of the mounts must be ~7mm out of position :s



When I first got her I could put my hand through the strengthening plate that held the mounts on the chassis side square, so whilst I was careful not to move them when welding I guess the damage was already done.



At this stage moving the mounts on the chassis really isn't gonna be practical, so I'm going to move the mounts on the axel. Well more specifically a mount on the axel! I've made up a new mount with a cammed bolt set-up that will allow me a total of about 8mm adjustment and I plan to weld in place of the old mount, offset by that 7mm I've calculated. With a bit of fine tuning she should be nice and square now.



With some luck the next update will include a video of her running!

[Johnnyboy]

Secondly she's always pulled a bit left, and shortly before I took her off the road I took her to have the suspension alignment checked out. The front was running a bit too much camber, but was essentially ok, the rear axel on the other hand was almost 1/2 a degree out of line, causing my left pulling. I broke out the calculator and dredged the back of my head for some trigonometry knowledge and decided that one of the mounts must be ~7mm out of position :s

It might not be your welding - do I remember your Watts Linkage was also bent? Maybe it was accident damage?

[Johnnyboy]

And could I ask who did the alignment check for you? And how much it was?

(I wouldn't mind having Miss January checked out and if they have already worked on one FB ....)

[Steve-A]

Good point John on the accident damage, I'd forgotten about the bent watts link. There were no other signs of accident damage on the chassis when I did all the welding, but those upper mount points were so weak they could have easily moved a few mm here if someone had slid the rear end into a curb or something.

I got the alignment done at Powerstation in Tewkesbury. http://www.powerstation.org.uk/ Seem like a decent bunch of guys, mostly just proper race cars and my car whenever I've been! It's about £100 for a full 4 wheel alignment, unlike a local tyre place that'll do tracking it's all done with lasers and computers and they can set toe castor and camber across all 4 wheels to within a couple of minutes of a degree of any specs you bring them. With the stock suspension you've only got front toe and castor adjustment, everything else is fixed, so maybe worth a call and see if they'd do it at a cheaper rate just to get her measured up?

It would also appear that maths managed to burn out my brain as I welded the new mount in the wrong bloody place :x According to my maths the rear should be square now but I'm right at the limit of my new adjuster rather than in the middle of it like I calculated. Oh well.

Will have a proper update later when I'm supposed to be working, I'm about to go out and probably flatten the battery by repeatedly trying to start her!

[MelloYello]

trying to start her!

Oh the anticipation!

[Steve-A]

Postpone that update. Looks like my original battery is dead, it only cranked for about 30 secs before going flat and now won't take any charge. I wasn't able to get a new battery right away.

I've got one sorted now and solved a number of issues. As usual the american base map seems to want to dump about double the required fuel in for cranking, I think I've got it which is good because I'm bored of de-flooding it... I checked early on that I was getting spark on all 4 plugs, and seeing as it's still not fired I tried to use the timing light while cranking, always tricky, as it seems the crank angle sensor is way out. Gotta wait for the battery to charge then I'll be able to get it sorted and hopefully she'll run.

[Steve-A]

Time for a proper update on this. You guys wanted the whole megasquirt story so here we go....

Since the last photo update I've got the final necessary items in the engine bay to start her.



And I finished off the extra mounting points for the rear coilovers. The mounts are ~40mm lower than they were before, and I've wound the coilovers up by 20mm. So overall the rear end now sits level with the front at the height I'd always wanted it to be, and I've gained 20mm more negative travel which should help it stick to the road better/be a bit comfier. I forgot to take pictures in the process, so here's finished shots.





So with some fluids chucked in I was ready to try and start her up!

And..... it's not gone to plan so far I was expecting teething troubles but not quite as many as I've faced. Firstly my battery has always been a bit weak, and after 3 weeks in the cold without being used the first day I tried to start it it went felt after about 10 secs of cranking. So I put it on charge over night, came to it the next day and it lasted 10 secs on cranking before going flat.

So £70 lighter with a new battery and was it third time lucky? no. It didn't start after a few seconds of cranking, so back to basics have I got fuel and spark. Fuel? yes and spark? well sort of. It was weak and at nothing like the right time. This is where megasquirt can be a pain. Not many people have used the 'rx8 mode' ignition set-up, which is for 4 individual coils, and so not many people have written about it either. I spent about 4-5 hours reading what I could online and triple checking all my settings and then noticed this....



It appears I'm an idiot! After unsoldering the connector and rewiring it in the right order, the spark is now firing in roughly the right spot, but it was still super weak. After some more hours I see again it's me being useless. I've always used coils with built in ignitors, and this is the first system I've used the Megasquirt to directly drive the coils. I'd got some settings wrong because I'd made assumptions without consulting the documentation about how to use the direct drive coils. But now it was dark and I'd flattened the new battery cranking for ages with timing light trying to solve my ignition problems.

So day three, 4th time lucky? nope . Got really close today, with the timing set right and a ball park amount of fuel to inject at cranking I got her to fire up past the 300rpm that's the magic number to switch from cranking settings to running settings, and she fell flat on her face. Again I'm doing it the hard way. I've always used manifold air pressure VS rpm (speed density) as my primary tuning algorithm but with the large throttle bodies the manifold air pressure will be weak and unreliable for most of the pedal travel. So the solution is to use throttle position VS rpm (alpha-n) tuning instead. And can I get hold of a base map for that anywhere? Nope. So I'm starting from complete scratch which is tough.

Still reading? good.

Now that my plans for future turbo have fallen by the way side*, I can use one of the newest Megasquirt features which are actually really cool. I decided to tune it with hybrid alpha-n. Which without writing pages and pages basically means it compares all three main variables, throttle position, manifold pressure and rpm to create a tune that is the best of both worlds. The good thing about this is that for this first start up I can use my speed density map from my mx5 as a decent base map It revved up coughing and spluttering to about 700rpm and just as it seems like it's gonna clear it's throat and wail that lovely rotary sound, it stumbled and stalled, and flooded. Before I got it to catch that well again the battery starts to run down again. So it's on charge over night and fingers crossed for tomorrow......

[ian65]

excellent progress there Steve... so close now.... are you going to get it dyno'd when it's running ok? It'll be interesting to see what it puts out.... have you had it compression tested yet?

[Steve-A]

I will be getting it dynoed yes. I helped them out at the garage with a dyno one saturday morning a couple of months back when they had a rotary bike in which was running on megasquirt in exchange for some free dyno time I'm gonna do the best street tune I can then see how I can better it on the dyno. I'm also hoping to do some comparisons of ignitions maps, the maps in power FCs for Fc and FD rx7s are radically different to what the distributer gives out, so it'll be interesting to see if there's much power to be gained with electronic ignition.

As for compression testing, never done it. Might be worth doing to see how it backs up my dyno results. She always hot started fine on the carb but on the other hand its never been rebuilt and has got 83,000 miles on the clock now.

[ian65]

mine starts well hot and cold but the compression test showed that it was well down on compression, especially on the back rotor.
It's good to get a test if you can, it's probably the only way to find out the real condition of your engine.