HELP! In the shop ... Bad ECU? One cylinder not firing near idle ...

twvette

Registered
Hi, I have an '06 engine in a custom off road vehicle (Polaris RZR). Took in for dyno tune and we discovered one cylinder (second to the end on the right side) is not firing at idle/low RPMs. It seems to wake up when get into higher RPMs. Engine in general runs very choppy before getting into mid to upper RPMs even when this cylinder seems to start firing. As a an example the dyno suggests need to lean the map out then on next run says it needs to be fatter. It is a new motor/ECU with only 100 miles. The mechanic is extremly knowledgeable but just want to make sure we might not be overlooking a known problem/symtom. Doe sit with or without a Power Commander connected. Injectors and plugs seems good. Our only other suspect besides the ECU at this point is perhaps a bad ignition switch/grounding issues. All stock except have the Power Command USB, GiPro w/TRE, GiPro Speedo healer. It seems this might have started when those mods and some other basic electrical work was done but honestly am not sure as this is a newly built machine I have only had a few minutes seat time in. Stock wire harness that was modified for the longer runs by company that does this for a living and seems to be testing out ok. Any input appreciated. Thanks ...
 
I would remove the PC USB, GIpro and speedo healer and see if that fixes the problem and the slowly starting adding them back in......also see if you can borrow an ECU from a local busa guy to make a run.

Good luck,
 
Back
Top