My cars is developing a habit of backfiring in the last few days, its a relatively stock SPI, is there anything simple it could be like a dodgy spark plug or plug lead?
Thanks.

Backfiring (if only on the overrun) is often due to an exhaust leak...
But if it does it under load I'd suspect dampness in the dizzy cap, or on the coil top.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I've got the coil pack engine and its dry as a bone, so could be an exhaust leak, I know that isn't out of the realm of possibility.

It's been a while, but if I remember, I had similar trouble with my SPI. It then developed into a major flat spot in acceleration upon take off.

It turned out that the MAP sensor was gummed up with oil and fuel rubbish, tricking the computer into over-fuelling. There is a really good series of threads on the UK mini forum by an SPI guru named Sprocket. Have a read.

Essentially, you need to replace the in line filter between the inlet manifold and the MAP sensor (inside the ECU), and also remove the ECU and sit it over a bar heater with some cotton wool up its bum overnight to get the gunk out. I did this and it fixed my trouble.

Even if this is not the cause in your instance, I found that the car ran better if I did this twice a year. The in line filters clog quite quickly.

Good luck.

_________________
1964 Morris "Cooper S" Group Nb Racer
1965 Morris 850
ex 1967 Morris Cooper S
ex 1969 Morris Van (Rover SPI running gear)