I've played with a funky way of doing exhaust animation that you could try. For the duration of the animation in your timeline, set completion from 0 to 100 over the period. But instead of leaving it linear in the timeline progression, set it to random. Then adjust the settings associated with that so you get a lot of spikes. I've had a neat result from that which looks like a fast moving jet exhaust. (But perhaps this may look like the sputtering you're talking of?) Of course it doesn't hurt to play with some other stuff in the fire settings too. (They affect the solidity and flicker more than completion does. From what I can tell, completion just provides a seed value that the other variables build on, so they can progress over time.) Other than random for completion, you can also set the timeline progression to one that looks like a sawtooth pattern. (I forgot the exact one, but I suspect its a sub-setting under the oscillation mentioned already.) You can adjust the speed by changing the number of "sawteeth" during the period in the timeline.

Also it might not hurt to stack some fire on top of fire, then you can get it to look more consistent over time. Just remember to make each one a master rather than an instance so they aren't in sync. I believe the fire is additive in appearance, so it's likely you'll do a bit of other adjusting so it's not too solid looking.

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Barbequed Pixels?

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