Hi peoples. I'm new to this site and would like to ask a question. I have an XJ400Z, 1983. When I'm starting her up for the first time, I find that after a couple of minutes, the tacko starts to flutter and then the engine starts to cough and splutter, but then will level itself out and will run fine. On some runs ( not all ) I can be cruising along and she'll start to cough and splutter and even flame out on me ( which I then pull the clutch in and gear down and release clutch to restart).
The last time she did this, my father just happened to be driving behind me and he said that as I pulled over, a great plume of black smoke came out of the left exhaust ( mind you, I did gear down pretty quick and made her rev quite hard, through frustration ) and she actually backfired!
Now, this does not happen all the time and when we take her to the mechanics, as usual, she runs fine and then makes us look stupid.
Any idea as to where to start looking?
Any help would be greatly appreciated
