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
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.
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!
I got some screen shots for you guys. This is the fuel ve table that I started with. It's rpm vs load%, where load% is essentially a combination of the manifold pressure and the throttle position, but exactly what balance varies across the rpm range and is set in another table.
After about 90 mins of driving with the auto tune feature on and the change resistance set to 'easy' ( and plenty of backfires, pops and flames) it was looking like this.
As you can see its quite different and the general shape resembles what I'd expect from a blended tuning mode table, but there are some nasty holes and lumps too. Some of these are areas I simply didn't get to drive in during my 90 mins. Other areas such as the over rich area above idle will never tune great with auto tune. In normal driving I'm only passing those cells while free-revving away from idle before putting the car into gear, so if the o2 is reading lean it probably means I need more acceleration enrichments (equivalent of accelerator pump on a carb). On the other hand if I'm only ever hitting that part of the map in that free revving situation then it wont matter and if ii were never to study the VE table itself I'd never know there was a problem.
So what I normally do is a bunch of auto tuning then come home and manually smooth the map out a bit, till I end up with something like this.
As i said previously in this post, all that was done with the throttle not making it fully open and the sensors calibrated as if it was so it's all a bit irrelevant now.
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 they all look 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 (WOT) 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.
Ex-rotor owner exploring the world of pistons and valves....
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