And here's an update on our MegaSquirt project.
Recap:
We got first start on the MegaSquirt today. It ran for a few seconds then died - but that's just a matter of getting the warmup tables going and getting the fuelling and spark tables dialed in.
It took us forever to get the thing started this first time because, as it turns out, I'd made a wiring error and on top of that Milltek's Euro Sovereign doesn't quite match the standard wiring diagrams provided. Go figure.
Well, guess what. In true Top Gear fashion, the "how hard can it be" factor appeared. It
wasn't just the tables that needed editing. The car would not stay running no matter what we did, and it was backfiring like mad at times.
1. MegaSquirt technically works with MAFs. The problem is that the entire system's software and settings seem to be oriented towards a MAP sensor instead of a MAF. It didn't seem to like our MAF very much. In fact, using the "proper" wiring scheme for it resulted in strange readings from the other sensors and totally improper fuelling once the thing started. We've discovered that (at least for our application) that we are going to have to get milltek's tune set up for a MAP, then at a later point convert to a MAF if he still wants to do so. We have ejected the MAF for the time being and fitted a 1-bar MAP from a 1994 Chevrolet Caprice instead. This improved matters.
2. At some point during this process (of discovering that the MAF won't work for now), the EDIS 6 control module blew its brains out and started firing the coil packs randomly. We replaced the module; the car got a lot happier, but it still wouldn't stay running for long, though it would let us rev briefly after start.
3. Since signs pointed to fuel starvation after start, we started checking for fuel. We discovered that the MegaSquirt wasn't controlling the fuel pump relay properly and that the car was sometimes shutting off the fuel pump after starting. We jumpered the relay as a temporary measure and got better, but not stable results. The jumper works fine while we are testing; we will be installing a new relay to do it properly - the MegaSquirt does switched
ground for relay control, while the original Jaguar fuel pump relay network expects switched
power.
4. At this point, we realized that our MSQ or configuration file was hopelessly cocked up from attempts to compensate for the problems the MAF had been causing - despite change controls. We started over with reloading a virgin codebase into the MS-II and a virgin configuration file. We threw out our old assumptions and started from scratch.
Between all this, here is the result:
It runs, consistently and for indefinite lengths of time (i.e., until we get bored and turn it off). NOW we're at the point of tuning and tweaking.
Now, this car has always been hard to start for some unknown reason. My 87 XJ has always started up immediately, where this 82.5 XJ with the higher compression engine would have to crank for a while and sometimes would take a number of attempts. Nothing has ever seemed to eliminate the problem, none of the "usual fixes" that apply to the US model Jags would do much, though the gear reduction starter we put on it aided somewhat and the MSD Blaster HVC coil we put on it mitigated some of the worst of it on hot days. It simply took two or three attempts to start it on average. Until now, that is.
Milltek was almost in tears when his car, despite having the roughest of tunes and running richer than heck, fired right up first tick - and kept firing up first tick, over and over and over again.
We have to neaten up the wiring and get some minor bugs worked out with routing and such, and then we can move on to dyno tuning.
