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Mefi3 question, switch serial data to dsnef, why??

Old 07-12-2017, 12:25 AM
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Default Mefi3 question, switch serial data to dsnef, why??

A fellow oso member with a 34 foot saber brought me his boat to look at today. Mefi3 ecus on modded 502s tuned by lingefelter years ago. Recently freshened motors, cannot and has never been able to use a rinda scan tool or scanner pro to watch data, retrieve codes etc. Files were converted from ptp to bin a while back to see if it helped scan tool connect, still did not.
So i tried scanning boat, would not connect, either motor. Pulled one ecu, temporarily installed in test harness in shop , would not scan. Went thru every table, flag and scalar. Timing table was a piece of garbage and lame, also found box checked "use serial data cable for dsnef". Well since we couldnt use serial data it stands to reason this dsnef crap was issue. Looked thru several other tunes, none had serial data switched for dsnef. Switched it off, bumped timing up where these guys had it at 20 degrees at 3800 to 4400 and loaded it up with mefi burn. Since he added tpis throttle bodys and modded intake manifold we added 5% fuel for good measure from 2400 up until he can tune it on the water.
Heres where **** gets real strange, when i upload a modded tune , after im done i religously download it then re-open it just to make sure it took. In this case the fuel tables changed but timing did not.
So somehow this dsnef switch fuks up your ability to upload the modded timing table when loading the tune, seems impossible. Turned serial data to dsnef back ON , uploaded tune, timing changes took that time BUT back to square one as now you cant scan the things w a rinda or scanner pro.
Pulled copy of tune off ecu again, turned dsnef crap off, uploaded it, downloaded it to see, test ran boat on hose. Finally scannable! !
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Old 07-12-2017, 12:29 AM
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So, has anyone else re-tuned a lingefelter tune or seen this on any mefi3? Just when i start thinking im figuring this stuff out i find more oddball stuff, smitty
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Old 07-12-2017, 01:07 AM
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Just asking are sure you do not have MEFI 4. whats the numbers on the ECM ?
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Old 07-12-2017, 06:39 AM
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Just so I can follow this thread correctly, The DSNEF you are referring to is "DSNEF is a abbreviation for Digital Controlled Signal To Noise Enhancement Filter. Which is a knock sensor filter module usually located in the PCM." Correct ? Just want to make sure I'm not missing or misunderstanding something.
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Old 07-12-2017, 07:35 AM
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Bup, definately mefi 3 ecus the most common ones like 502 mag and 500efis used. These are lingenfelter packages from day boat was new. Lingenfelter modded 502mags w dart heads. Bigger cam, ke manifolds, dynoing and tuning. They sold it as s 540hp deal, custom valve covers with logo etched in them. The owner, BG3, might chime in, boat has NEVER been scannable in time hes owned it

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Old 07-12-2017, 07:52 AM
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Sb, yes, digital noise filter enhancment. How telling the ecu to use the serial data wire for a function that ive never seen used wihich accomplishes nothing other than making motor un scannable did anything with a purpose makes no sense. The knock sensor appeared stock.
The OTHER anomaly is owner has original dyno sheets, he actually took time to do a overlay of my 502mpi dyno dats and frank from marylands 502 data. These motors had a signifigant tq dip from 3000 to about 4000 rpms, ligenfelter tweaked stock 502 timing tables slightly higher but DROPPED total timing down to 20 degrees in middle of this tq drop then , whoo, hoo, brought it back to a whopping 26/ 28 at wot at higher rpms.
Im trying to wrap my head around wtf the dsnef crap was done for, am i missing some "magic" function that mefi3 does that ligenfelter took advantage of OR were they just doing the best they could back in 2000 and they fukked up??? Btw, these ecus have been locked since lingenfelter did them, the owner recently got unlock codes from them.
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Old 07-12-2017, 08:02 AM
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There were many spots in timing tables that just had stock 502 mpi numbers in them too which are lame as hell in a attempt to get these motors to.live forever at wot on 85 octane or something! Just think, guys been running 93 octane for 12 years on a tune that was at 26 to 28 degrees total timing!
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