The V8 Owners Forum -

Hi
Im ditching my 3.9 hotwire and going on to micro squirt
I believe there are issues with low / high impedance injectors not sure what I have in my 3.9 1998 disco 1
Has anybody gone onto this system or know s how to identity low or high impedance injectors
Thx
Andrew

Measure one with a DVM. Low will be under 3 ohms or so. High, something about 10 or more.

The Lucas flapper injection uses low - and a resistor pack. All later Lucas, hotwire onwards, high. So on a 1998 vehicle, high.

Personally, I'd not go for a MicroSquirt, which is really for bikes etc where space is at a premium. You're not going to be short of space on a Disco. The standard MegaSquirt range is more versatile, although more expensive.

It also depends on your objectives. With the ancient flapper, it is easy to get MS to work better than it. With later systems, the difference is less marked. Unless you go to full house sequential, which really means MS3X. Of course if you have a modded engine, MS is easier to tune for that than a stock system.

Thanks for that the 3.9 disco engine is in my stag and I just wanted a basic fuel only upgrade with a wide band o2-sensor / controller
Thx

If possible I would go Megasquirt if the cost difference is small, you may decide to use the ignition side at a later date. Being able to map it properly can make a big difference to the Rover engine. I have the MS3 and it sits neatly hidden away beneath the glove compartment plastic inner housing and the metal underside of the dashboard.
Previously I ran a modified flapper style ECU from Mark Adams, the megasquirt setup was a huge step forward in driveabilty.

Yes - I went from the flapper system on my SD1 to MS2. The really big improvement was low to medium revs grunt. Became just like a V8 should be. And it no longer had good and bad days. Not sure you'd get the same improvement with a hotwire, though.
One advantage with the MegaSquirt2 on the flapper is you can dispense with the injector resistors and drive Lo-Z injectors directly in batch mode, using PWM. Don't think you can with the MicroSquirt.