You have changed ever sensor? That's expensive! I had a similar problem on my SL1 and it was the coolant sensor. The little pin inside (where the wires were attached) was broken off, so the problem exhibited different symptoms when it jiggled around (making contact whenever it wanted to!!!). So...sensors are good...maybe check the connectors? Sorry I cant be of more helpRon
Answera buddy had a 91 its was doing evedrything under the sun wouldn't shift rough idle turn off back fire everything turn out to be the computer $40 at local junk yard 15mins of work all fixedOut of time.
Too much PSI.
Backfire is normally caused by engine out of time, or spark plug wires installed incorrectly.
As with any engine, timing, and also carb problems.
It's lean. You have to figure out why.
Timing is off. You may need a new timing belt.
Several issues can cause a back fire:OverheatingLean mixtureFaulty ignition
check your coolant temp sensor also is the ses light on,posible egr fault
That usually means the engine is lean. Could be a vacuum leak.
I, too, would like to know the answer! I have a 1993 Polaris Trail Boss ATV with the 250 cc engine... it tends to backfire when letting off the throttle.
Timing , pure and simple. If the timing is out then your fuel / mixture will detonate when the piston is in the wrong position in the cylinder. This can lead to a backfire
The timing of the engine is off or the spark plug wires have been hooked up incorrectly.