21 AprSwitched to Direct Coil Control over from EDIS

Amazingly, it turns out that the EDIS system has been running with the VR sensor wired with the wrong polarity, ever since I installed Megajolt thousands of miles ago! It explains why I haven’t been able to run over 4000rpm with my EFI, why my tach never worked past that RPM on Megajolt, and why over the past week the RPM signals have looked a little odd even at idle in the MS3 datalogs (SD card logging is so convenient and useful).

I switched over to direct coil control this weekend and only got it started late this evening. Even after wiring everything up and getting good logs in the tooth logger, it would start then immediately die. Changed the recommended settings to falling edge instead of rising edge for the VR sensor and it suddenly sprang to life.

What’s clear is that my fuel map will now need tuning again as the EFI is working more accurately, but the engine feels so much stronger now and will even tick over at 600rpm solidly!

Have had a quick test for spark cut rev limiter and it works beautifully, which was one of the reasons I always wanted to omit the EDIS and go direct coil control. Just need to find a push switch to get launch control working, and get some wheel speed sensors made up to try out traction control.

2 Responses so far.

  1. Dave Townsend says:

    Hi Rick,

    Interested to read your report on electronic ignition systems.
    i have recently bought a very sorted Triumph Spitfire 1500.
    It is fitted with a Megajolt ignition system and the car starts and runs well.
    My problem is the tachometer.
    The original one stopped working after a couple of short rides so I bought a second hand one
    on ebay, RVC like the original.
    Worked fine yesterday on a blast through the country lanes of Essex but on the way back it
    stopped working.
    I took it out and dismantled it but nothing seemed amiss so put it back together again.
    The original tacho is in for repair but when it’s returned I’m not putting it back only for it to stop working again!
    Could it be the Megajolt system is too powerful for the tachometer and I need to put a resistor into the live cable?
    Any advice would be welcome.

    Could it be the Megajolt system is too powerful for the tachometer and is

  2. Rick Baines says:

    Hi Dave, where does the tach take a feed from, and what version of Megajolt is it? The V4 has a tach out, that should pose no problems with an RVC tach. Alternatively you can take a feed from the EDIS unit itself, can’t remember which pin but a google search should be able to tell you.