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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Thu, May-30-2019, 12:53:38 AM   #11
HassanEido
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Default Re: boosted S54 use MAF, MAP or IAT only and why? Who is your tuner?

That depends largely on ur tune tbh. If u have an hp dme do the map sensor its a more complete setup. For me though I work at sea level, and live at a few hundred ft of elevation, I won't be going to a MAF since there will be zero difference in my case, and I don't have an hp dme. No regrets here, but I always advise ppl with an hp dme to go map. It's only like a 50 dollar sensor
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Custom exhaust thread and dyno http://m3forum.net/m3forum/showthread.php?t=569086
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Old Thu, May-30-2019, 01:15:49 AM   #12
kokgo20
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Default Re: boosted S54 use MAF, MAP or IAT only and why? Who is your tuner?

Quote:
Originally Posted by HassanEido View Post
That depends largely on ur tune tbh. If u have an hp dme do the map sensor its a more complete setup. For me though I work at sea level, and live at a few hundred ft of elevation, I won't be going to a MAF since there will be zero difference in my case, and I don't have an hp dme. No regrets here, but I always advise ppl with an hp dme to go map. It's only like a 50 dollar sensor
Going with a MAP sensor, does my HP DME require any hardware modifications?
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Old Thu, May-30-2019, 01:53:35 PM   #13
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Default Re: boosted S54 use MAF, MAP or IAT only and why? Who is your tuner?

Alpha N is clearly worse, at least considering the car over a variety of conditions, or BMW wouldn't have gone through the effort of developing an entire different engine management system for the CSL.

I had 3 different Alpha N tunes on my car before the MAP conversions became a thing, and none of them were as consistently good as the MAP based setup. The MAP setup allows the car the feel stock, always, in the best meaning of the word.
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Old Thu, May-30-2019, 04:43:52 PM   #14
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Default Re: boosted S54 use MAF, MAP or IAT only and why? Who is your tuner?

MAF is terrible for anything highly modified - they're exceedingly sensitive to any change in the intake tract, and depending on the sensor and what your definition of "boost" is they can exceed their ideal measurement range rather quickly.

Alpha-N is going to be inconsistent by nature - your engine is running off of a table with throttle position and RPM, and while there's a barometric sensor in the DME, there's no actual feedback for the amount of air going into your engine (in open loop).

MAP/ Speed Density is extremely broad, as long as you dial it in on a dyno to account for the engine's *actual* volumetric efficiency (VE). If MAP based is feasible, that's the route I would go
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Old Thu, May-30-2019, 04:54:48 PM   #15
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Default Re: boosted S54 use MAF, MAP or IAT only and why? Who is your tuner?

Map.

Alpha-N feels like the car is stuck in limp mode.

On the same note I haven't seen or heard anyone running a boost setup utilizing the map sensor.

Keep us posted.

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Old Thu, May-30-2019, 05:53:57 PM   #16
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Default Re: boosted S54 use MAF, MAP or IAT only and why? Who is your tuner?

In *theory* a maf based setup would be ideal. If it works properly, the maf signal would represent how much air is entering the engine at that exact moment in time, and the amount of fuel required would be roughly proportional to that value. In practice it doesn’t always work that cleanly. The sensors are very sensitive, can restrict flow, and minor changes to the intake tract can generate erroneous data.

Alpha-N doesn’t measure any engine parameters directly. It’s dependent on having a fairly accurate model of how much air is entering the engine for a given throttle / icv position and rpm. This works reasonably well on a N/A engine where flow changes are near instant. Problem is with boost, particularly turbo chargers, which takes time to build pressure. You have no real way of measuring how much boost you’re getting.

A map sensor measures pressure past the throttle bodies. Combine that with displacement, rpm, and temperature, and you’ve got a decent idea of how much air is entering the engine. And since you’re actually measuring pressure, you can in theory accurately fuel the engine as boost builds.

All that said, it’s a little unclear to me how the CSL ecu works. It calculates rf from both the map sensor and throttle position. I don’t know what’s prioritized and when.
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Old Thu, May-30-2019, 06:41:04 PM   #17
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Default Re: boosted S54 use MAF, MAP or IAT only and why? Who is your tuner?

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Originally Posted by terraphantm View Post
All that said, itís a little unclear to me how the CSL ecu works. It calculates rf from both the map sensor and throttle position. I donít know whatís prioritized and when.
Totally agreed. If I had to hazard a guess on that one, I would imagine low load uses the MAP sensor, where you have maximum vacuum to measure off of, and high load/ WOT uses TPS since the MAP sensor isn't going to have much of a range.
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Old Thu, May-30-2019, 07:23:09 PM   #18
terraphantm
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Default Re: boosted S54 use MAF, MAP or IAT only and why? Who is your tuner?

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Originally Posted by Drewster View Post
Totally agreed. If I had to hazard a guess on that one, I would imagine low load uses the MAP sensor, where you have maximum vacuum to measure off of, and high load/ WOT uses TPS since the MAP sensor isn't going to have much of a range.
The stock map measures up to 1.2 bar so it should have enough range for a N/A motor.
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Old Thu, May-30-2019, 08:11:39 PM   #19
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Default Re: boosted S54 use MAF, MAP or IAT only and why? Who is your tuner?

Quote:
Originally Posted by terraphantm View Post
The stock map measures up to 1.2 bar so it should have enough range for a N/A motor.
Wouldn’t the stock MAP sensor be enough for a super charger 11~12 psi boost limit also?
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Build thread---------- INSTAGRAM ------------ROTREX REBUILD-------------Now offering custom digital gauges

2004 SMG PY/BLK - 600 TCKline - CPI Headers & resonated Sec1- Stoptech BBK 6 pod front & 4 pod rear with steel lines - 75mm Studs conversion - SDW monoball RTABs - AKG subframe bushings - Multi color AEs - FR-X 3.0 Projectors - Smoked Side markers - Euro bumper - V1 with hard wire & Stealth one - M Track Mod - ZCP steering rack - Dual LI - CSL Style diffuser - SCZA Exhaust - E9x Door handle LED retrofit - SCZA CSL bootlid - VEI systems custom air vent A/F & boost gauge - VEI custom air vent Water temp & oil pressure guage- Active Prima plus + HTE performance tune - Custome fab intercooler - Mishimoto Radiator & Oil cooler - H&R front Sway - UUC camber arms - keyless & push to start system - clear bra - interiors red stitching contrast - Apex PS7s - 16" Spal fan
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Old Thu, May-30-2019, 08:18:16 PM   #20
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Default Re: boosted S54 use MAF, MAP or IAT only and why? Who is your tuner?

Quote:
Originally Posted by kokgo20 View Post
Wouldn’t the stock MAP sensor be enough for a super charger 11~12 psi boost limit also?
No u will need a 2 bar map sensor, assuming it needs to measure boost on low loads thru the map sensor.
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Mods:
-Custom CF airbox
-SSV2 catless headers(with a modified collector extention), Custom 2.5" dual sec1, Custom sec2 2.5" dual with e9xM X pipe, SuperSprint Race inspired custom section 3..
-Cat Cams 280 272.
-Custom dyno tune
-Tms pulleys and electric fan conversion
385.7 whp 288 wtq

Custom exhaust thread and dyno http://m3forum.net/m3forum/showthread.php?t=569086
Cams thread and dyno http://m3forum.net/m3forum/showthread.php?t=554439
Custom cf airbox thread http://m3forum.net/m3forum/showthread.php?t=595180
Why not to use after market bearings with surfacetreatments and /or increased clearance
http://www.m3forum.net/m3forum/showp...4&postcount=10
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Discussing boosted S54 use MAF, MAP or IAT only and why? Who is your tuner? in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)