Hi Scotty,

I have a 2.4 liter ecotec in my polaris slingshot. When I first bought it new discovered that the vehicle would buck like a bronco if i did a fast accel. off the line. As time went on I now have a random misfire when the engine gets up to operating temp. After I installed my supercharger it was still there but the came with new injectors, map sensor and air temp sensor and new spark plugs.

I can see the miss on the air/fuel gauge, when it is idling normal it is around 13 and steady, when the miss starts the gauge goes up to 15-16 and is very jumpy. I have scanner but it looks normal other than the spark advance starts to dance a bit. I sent the parts back to the supplier and they sent out new ones, no different. I also sent them the ECM and they confirmed it ran fine on their test vehical.

I have check all the vacume lines by using propane and visual inspections an all looks fine. So.. at this point.... help!

The engine only has 6000 miles on it and runs strong when working properly, power now actually sucks me back in the seat.

By the way, the missing comes in events as in when it starts to miss it will last several seconds then go away or at least improve. I have a video of one event that shows what happens at the A/F gauge.
When at idle it will running normal and smooth but suddenly it will give a series of misses, then get better the the misses come back again. After a bit it goes away but I can feel the misses at cruising speed and really bad near redline.

well, first do a wet and dry compression test on the engine, but if that's OK, you either have a fuel injection or an ignition problem. Those are GM engines, and a good gm scan tool can be hooked up, then you drive it till it acts up, the tool memorizes all that data, and it can be analyzed to find the culprit.

Apparently the CMU is not a standard automotive unit and requires a unique scan tool. I bought the software and adapter cable but it provides limited information. I have driven it with it hooked up and have the stored data but the shop cannot locate the problem when they view it. I did a wet and dry compression test and all is good.