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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 Wed, Jun-13-2018, 10:39:46 PM   #11
grannyknot
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Default Re: E46 M3 throttle balancing

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Originally Posted by BBRTuning View Post
I just did this on my S54 for the hell of it, having recently had experience doing this successfully on Porsches at work.

I used a Redline-Weber synchrometer tool to measure actual airflow. Cylinders 1-5 were within ~1.0 kg/h of each other, but cylinder 6 was almost 3 times the others. (many say 0.5 kg/h maximum variance is acceptable).

I was surprised to find this considering that, as you said, the throttles are all connected via a common air rail. I suspect that the air rail does cause some improvement in balance but that significant variances can still show up. The engine of course wants to consume much more air than it is being “allowed” to by the throttles, even at idle, so a particular cylinder with a further-open throttle blade will consume more air. I also believe that the air rail is in a sense self-balancing, within itself, so that it will feed very close to equal air to each cylinder, regardless of individual throttle angles.

Anyway, I was able to get them all to within 0.2-0.3 kg/h without much trouble. As I have a stand-alone ECU, I temporarily disabled the IAC and ran the engine from the throttles only (about 1% opening required for 1000 RPM idle), although I did leave the air rail in place. While this wouldn’t be an acceptable condition to sync the throttles (as the individual throttle sync adjustments are essentially the throttle stops, and at this point the throttles would all be pulled off the stops), I was able to confirm that airflow stayed pretty well balanced even as the throttles open.
I come from the days of balancing each throttle body individually with vacuum ports and adjusting screws but since the s54 doesn't have provision for that am I right to assume you are balancing T/B on your laptop through your standalone ECU?
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Old Sun, Jun-17-2018, 04:06:30 AM   #12
BBRTuning
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Default Re: E46 M3 throttle balancing

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Originally Posted by grannyknot View Post
I come from the days of balancing each throttle body individually with vacuum ports and adjusting screws but since the s54 doesn't have provision for that am I right to assume you are balancing T/B on your laptop through your standalone ECU?
The S54 has adjustable throttle stop screws for each throttle. From the factory the screw heads have black plastic covers on them. The synchrometer tool simply measures airflow through each throttle, and the stop screw is mechanically adjusted so that each throttle is flowing the same amount of air at idle. No electronic adjustment is done, or is possible, since all 6 throttles are controlled by the same throttle linkage and actuator.
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Old Sun, Jun-17-2018, 02:09:51 PM   #13
terraphantm
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Default Re: E46 M3 throttle balancing

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Originally Posted by BBRTuning View Post
Even on the stock DME you could do this, as I found that even running the car as standard (off the IAC with the throttles closed at idle) showed enough cylinder-to-cylinder variance to make it worth adjusting. You should be able to start up the car with the airbox removed on the stock DME; you'll probably want to unplug the MAF so the car runs in an "Alpha-N" mode so it will idle.

I bought the standard Redline-Weber synchrometer. The S54 throttles are 50mm ID so any tapered-shape synchrometer made for throttles in that size range should be fine.
I have had some limited success disabling the ICV with the stock ECU. Works for the most part, but have some stalling issue. Might be good enough to make the adjustment work better though?
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Old Sun, Jun-17-2018, 02:18:06 PM   #14
bigjae1976
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Default Re: E46 M3 throttle balancing

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Originally Posted by terraphantm View Post
I have had some limited success disabling the ICV with the stock ECU. Works for the most part, but have some stalling issue. Might be good enough to make the adjustment work better though?

Hmm...would an ICV delete be possible for a track only car?


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Discussing E46 M3 throttle balancing 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)