PINNACLE PERFORMANCE CLOSED LOOP EFI TUNER

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Shavonne Briggs
5 years ago
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1 PINNACLE PERFORMANCE CLOSED LOOP EFI TUNER Jim Burwell and Torrey Clawson, co- owners of Pinnacle Performance in Ogden, UT has developed a unique proprietary "closed loop" EFI tuner for snowmobile engines. After successfully field testing their technology on NA and boosted sleds for several years they decided to see the actual independent test data that we could obtain here with our fully instrumented SuperFlow 902 engine dynamometer. How accurate is the Pinnacle tuner in creating the desired A/F ratio numbers? How quickly does the Pinnacle tuner change fuel flow to create the desired A/F ratio numbers? They shipped this Arctic Cat M1000 a stock sled with only an SLP Ypipe, single pipe and non- SLP muffler to DTR in Batavia, NY to answer those questions. The Pinnacle EFI controller can be best described as a "piggyback" tuner that modifies the injector pulsewidth of the sleds' stock ECU either extending or shrinking the 12vdc signal to each injector to add or subtract fuel as necessary to obtain the desired A/F ratio. Other commonly used EFI tuners such as Boondocker, Power Commander, and Dobeck are piggyback units but these can be referred to as "open loop" tuners. "Open loop" tuning devices must be programmed by the user to add or subtract specific amounts of pulsewidth (either in milliseconds of pulsewidth, or % of pulsewidth) as desired by the dyno operator/ sled owner. With open loop tuners, % changes are the best since milliseconds of pulswith change needed at, say, 70 degrees F is improper at 0 degrees F. But % change are surely more accurate. "Closed loop" tuners use measured airflow/ fuel flow to determine what fuel flow is needed to create the desired A/F ratio. Some automotive closed loop systems use mass airflow meters to measure airflow, but that sort of system uses a heated sensor that can be fooled by snow dust that if tried on a snowmobile might fool the device into thinking airflow is much higher than actual. But with the Pinnacle tuner, A/F ratio is measured by a Bosch wideband O2 sensor (a VW part available at parts stores for less than $60). On the M1000, the O2 sensor bung was welded into the top of a glasspack muffler with a spare bung for the dyno Innovate wideband O2 sensor (another VW part) to give us recorded A/F ratio. The Pinnacle tuner is similar in concept to the new Power Commander V which can be "autotuned" with a separate AT- 200 box and wideband O2 sensor. But the PCV Autotune option is very slow to react, and make changes to the fuel flow. It's designed to create temporary fuel flow changes that can eventually be accepted and made part of the PCV map, but it takes lots of time at each RPM/ throttle position to do that. And there's no provision to autotune based upon boost pressure. For example, if we autotune a PCV equipped EFI sled on the dyno it might take four gradual dyno runs to get the AT- 200 to create an acceptable WOT fuel map. So on the dyno, it's easier to just enter in a fat PCV map, make a dyno test, then adjust the fuel flow manually to what % is needed to create the desired A/F ratio. It's just math, and then it's done. But we have a $100,000 dyno system to do this with. People who try to tune their modified EFI sleds in the field by looking at spark plugs and piston domes, and then tweaking fuel flow by % or milliseconds of pulse width can easily get lost.

2 But what we saw here with the Pinnacle closed loop EFI tuner was an instantaneous change of fuel flow to create the desired A/F ratio! Jim and Correy flew into the Buffalo, NY airport (30 miles away on the same road as we're on) and were most anxious to see how their tuner, running perfectly at ,000 ft would react at 700 ft. Here's the baseline test as the sled came out of the crate and set up on the DTR dyno. Note that the glasspack muffler had two O2 sensor bungs welded onto it one for the Pinnacle controller wideband sensor, and one for the dyno Innovate wideband sensor which reads out as LamAF1: EngSpd STPPwr STPTrq BSFA_B FulA_B ElpsTm LamAF1 DenAlt FulPrA RPM CHp Clb-ft lb/hph lbs/hr Secnds Ratio Feet psig The Pinnacle controller allows for tuning different desired A/F ratios at various throttle positions and every 500 RPM. In this case, Torrey was miffed with the low HP so he tweaked the 100% throttle A/F ratio less than one point leaner to maximize HP: EngSp STPPwr STPTrq BSFA_B FulA_B ElpsTm LamAF1 DenAlt FulPrA RPM CHp Clb-ft lb/hph lbs/hr Secnds Ratio Feet psig

3 As the elapsed time column shows, the A/F ratio immediately leaned out to max HP at just under 13/1 as measured by the dyno wideband system. Note that fuel flow lb/hr dropped instantly to create the commanded A/F ratio. So here we have a stock M1000 with proven good SLP Ypipe and single pipe, but with what would turn out to be a very poor design glassspack can muffler. Could it have insufficient backpressure that s necessary to create optimal supercharging of the intake charge? Next, Torrey installed a different name brand (but not SLP) glasspack muffler. As the next dyno test shows, this glasspack muffler is much tighter than the one that came on the sled. The Pinnacle controller was still tuned to create max HP A/F ratio and as this next test shows, the fuel flow dropped to match the reduced airflow and created optimal HP. This latest muffler had only one O2 sensor bung so we had no dyno generated A/F ratio, but we can assume that actual A/F continued in the 13/1 range based upon the low BSFC: EngSpd STPPwr STPTrq BSFA_B FulA_B ElpsTm DenAlt FulPrA RPM CHp Clb-ft lb/hph lbs/hr Secnds Feet Psig

4 ================================================================== Since the response time from O2 sensor to Pinnacle controller appears so quick, it s easy to see why this should be an optimal way to provide extra fuel for pressurecharged engines. The Pinnacle controller can not only alter stock injector fuel flow but also can be programmed to energize and control the net A/F ratio via suplemental fuel injectors on pressurecharged engines. This seems like an ideal method compared to open loop alternatives. What about O2 sensor life/ failure? Torrey s M1000 sled has had the same O2 sensor in the muffler for several years with zero problems. The Bosch O2 sensors typically have a one year warranty, and if there is a failure of the O2 sensor with the Pinnacle controller, it is said to go into a limp home mode with 10% extra fuel.

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