wrcbonk Posted September 24, 2015 Share Posted September 24, 2015 (edited) After reading the thread Coil Suggestions I have some follow up questions for the RB group, but didn’t want to hijack Blob1620’s thread. I have a very stock Series 1 rb25det swap in my s30: stock ecu, STOCK COILS, throttle body, no downpipe, 2.5-inch exhaust, freddy plenum, the intercooler is probably 50% bigger than stock, stock fuel rail, injectors, and FPR. I am currently running the boost at the stock max of 7-8 psi through a manual controller and I have a wideband. Naturally, my engine stubbles from @4500 to 6000 where AFRs plummet to 10 and the engine runs roughly. Common wisdom (Hybridz and SAU) states the ecu is retarding timing and adding fuel to preserve the engine from knock as US fuel is lower in octane. This is not a new story to the group. There are numerous changes that can be made to add power and I intend to start making those changes, but my first priority is to smooth out my rev band. I am more interested in smooth running than power at the moment. My question is this. Should my first step be to obtain a programmable ems allowing me to tune for US fuels or is replacing the coils more important? Put another way, is the rough running more a function of poor ignition performance or the fact that the fuel and timing maps are locked and meant for higher octane fuel? Thanks Bill Edited September 24, 2015 by wrcbonk Quote Link to comment Share on other sites More sharing options...
helghast7 Posted September 25, 2015 Share Posted September 25, 2015 Both honestly. Stock coils/ignitor sucks and so does a computer that dislikes when you change anything from how it used to be in the original car. If you can afford a new computer then its only about another 200 max to do an ls coil swap anyways. Quote Link to comment Share on other sites More sharing options...
winstonusmc Posted September 25, 2015 Share Posted September 25, 2015 The RB25 computers are tuned to riches and retard after you go over stock boost levels. Also you need to check all yourights sensors, a bad coolant temp sensor will make your engine run rich and misfire under boost. Quote Link to comment Share on other sites More sharing options...
wrcbonk Posted September 25, 2015 Author Share Posted September 25, 2015 Thanks guys, I will look into testing my coolant temp sensor. Doing some other research I found that another benefit of EMS is adjustment of spark dwell, which can be optimized for the LS coils. Quote Link to comment Share on other sites More sharing options...
Bernardd Posted September 25, 2015 Share Posted September 25, 2015 Check out nistune for the stock computer tuning info. Quote Link to comment Share on other sites More sharing options...
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