I solved the electrical issues eventually. What I believe happened is that I fitted an alternator that was correct for the year but not correct for my car. Seems that NA alternators were self regulating but NB alternators are regulated by the ECU. Since my ECU has been replaced with a mega-squirt I need regulation somewhere and I didn’t have it on the test drive that blew the electrics. So lesson learned and we are back on the road.
In fact the five has been round Oulton Park and Castle Combe since and worked well. Both these track days were wet though, especially Castle Combe but I pressed on and had a laugh once I’d gained confidence in the grip.
Clocked up about 80 miles round Castle Combe and similar at Oulton.
This all started with a noisy alternator bearing and a sticking starter motor. A starter was acquired from ebay and that’s fine but the alternator was the start of weeks of pain.
I got a new alternator from ebay which when fitted made some odd whistling and after a brief test round the block the car promptly died. Turns out that after having the new alternator tested it is faulty and pretty poor quality.
I had new bearing put in the old alternator and refitted it but we’re still dead. The 80 Amp fuse was blown so I fitted a new one and we’re still dead.
After a bit of testing it turns out the engine management fuse was blown. Fitted a new one and it blew straight away. The car is fitted with a DIYAUTOTUNE megasquirt. So not straight forward to diagnose but at least I can talk to the ECU with a PC. I took the ECU out and put it on the bench to test. All checked ok.
Then I go hunting for a wiring diagram. Eventually I found a really handy document which is here if you need one. Mazda+MX-5+Miata+2000+Wiring+Diagrams
Slowly working through the wiring diagram I isolated all the engine wiring loom eventually and the problem was still there. In desperation I hooked my meter up between the failing circuit and earth and disconnected every plug I could find one by one until the meter showed open circuit. Eventually I found the part of the loom that had the fault.
By this time the car is in lots of pieces and spread all over the garage floor.
Could not see anything obvious in the loom and then without finding anything at all the thing starts working. Now I don’t know what worse, having a fault to find or having it working and not know what the fault was 😐
Winter saw new super pro polly bushes all round. New springs, 30mm lower. New rear sill panel repairs. Lots of cleaning, painting and underseal. Prior to a damp run out at Donnington last week I put a new water pump, cam belt, cambelt idler and tensioner in. Donnington was cut short however by a screaming alternator bearing and sticking starter motor.
Second hand alternator and starter on on the way. Fingers crossed this is the start of some summer track fun.
Took the MX5 to Oulton park today for a Javlin organised trackday.
Since taking it to Donnington a little while ago, I’ve put a roll bar in it, changed to braided hoses and racing fluid. Then splashed out on a set Yokohama AD08R tyres.
The tyres have transformed the cars grip levels. It now just hangs in on the corners where before it would have understeered and eventually melted the tyres after 10mins.
I still couldn’t bring myself to rag the piss out of it though, seeing as it had to get me home. A couple of fast laps was enough to get the brakes smoking, especially the near side front for some reason.
Oulton Park circuit is fantastic. I found it a bit intimidating to start with and never really relaxed too much. There are couple of corners where if you get it wrong, you are going to be in the shit. I’d like to go back again but with a bit more power next time 🙂
The car was in good shape after Oulton so I also booked an eve’ session at Donnington the following Thursday. This was run on the GP circuit. Again the car went well with loads of grip. Everything passed us on the straights though which is getting frustrating.
Got shot of the Westie and have now got an MX5, this completes the hairdresser collection by complementing the Boxster.
It has some mods which should work on a track. Hope to get it on some track days this summer.
Brief details of mods are:
- It has a Megasquirt ECU, remapped to 160 bhp. sports brakes, adj suspension, stainless exhaust and Torsen LSD.
- Custom made aluminium inlet manifold and bike throttle bodies, aluminium trumpets and a custom made baseplate to fit a piper cross airfilter
- Full Stainless exhaust system which comprises of a stainless manifold, custom made centre section with a 200 cell sports cat and resonator box, the back box is also stainless from mx5 parts.