I finally took my “new to me” 2011 RZR-4 800 camping/riding this weekend. My RZR has a UTV Inc. sealed air intake (my doing), and it has an aftermarket Trinity Stage IV exhaust (on it when I purchased it). The RZR ran good except for 2 things of note. One thing to add was that I thought the 2 items might be related to old/bad gas in machine from previous owner. So I put fresh premium fuel in, but no change.

1. It sometimes backfired on decel. Prior to my trip I tried to seal off any exhaust leaks with some type of Permatex stuff (can’t remember type offhand), but it was junk. Rather than being like RTV and somewhat flexible it hardened, and just broke off). Again prior to my trip, I purchased a Wiseco Fuel controller to see if that would help since I noticed it backfiring just driving down my street. Didn’t seem to change it, but I’m just in the default settings. I haven’t messed with it.

I’m going to try some RTV stuff this time and try to seal off any exhaust leaks, but I don’t understand why it should be required since most aftermarket exhausts seem to be slip joints where one pipe slides into the other without any gasket.

2. The other thing I noticed is that the engine seems to sputter at very low or just creeping RPM’s (I didn’t think at the time to see what rpm, but I know just driving less than 10 mph down the mountain trails it would sputter until I gave it more gas). So long story short, machine starts up and idles fine, if I just feather the gas it sputters, give a little more throttle it ran good.

Not sure if the sputter and backfire are going to end up being related or not.

I plan on removing the bed again to RTV the exhaust, and I guess possibly check/change the plugs. Any ideas on the sputter at such low RPM, but run great otherwise? Anything else I should check? Any weird sensor thing? Any help appreciated.

Utah RZR Rentals