ECU & Forced Induction [Archive] - Bimmerfest - BMW Forums

: ECU & Forced Induction

12-28-2005, 11:32 AM
Hi, I just thought I would see if anyone had information on this topic...

I own a S52 M coupe with Dinan stage I upgrades. I would really like to upgrade it with either a turbo or a supercharger. My prior experience is with turbochargers, and I prefer them, however I am also interested in a supercharger in this application since #1, I think it is a much easier installation, #2, I obviously do not plan on running crazy amounts of boost, and #3 they are less prone to lag.

I have seen various kits, but I guess the questions are has anyone done this on their own (without a kit)? Just giving it the quick once over it seem like you could have a supercharger bracket machined and do this yourself without too much trouble, or purchase/fabricate an exhaust manifold with a T3 or T4 mounting point. I have done this sort of thing in the past, and it makes for a pretty fun project.

Secondly - and this is more my question than the physical installation of the kit (and this applies to the kits as well), how does the ECU compensate for modifications like this? I am unfamiliar with BMW engine management. On my Lotus, I installed a larger turbo, RC Engineering 550cc injectors and run a Haltech engine management with a wideband O2 sensor system to control/tune it all.

However, some kits look like just a supercharger/bracket, piping, & injectors. Surely something must be necessary to control fueling/timing though? I have noticed my car has a warning sticker saying it has been modified with Dinan software; does this mean that the ECU can actually be re-programmed to compensate? Or is this the way all OBDII ECUs operate?

01-07-2006, 01:41 AM
The ECU (with stock or Dinan tuning) should be able to compensate for *small* amounts of boost, but as far as I know it's not really designed to handle above-atmospheric intake pressure. The S52 engine has a knock sensor so theoretically it should be able to retard timing slightly if it detects detonation, but for any reasonable performance gains, I'm pretty sure you'll need a separate way to control/tune the fuel and timing. Actually I've been wondering about this too, because I've heard that people are reluctant to use stand-alone fuel and ignition management units since the stock one is "so good"... I think most FI kit providers just reprogram the stock ECU's tables.

I'd like to find out more about this too, so anyone who has info, please post here.

Mr Paddle.Shift
01-07-2006, 11:06 AM
I am running a Technik Engineering ASA Stage 1 supercharger kit on a M54B25. Not by any chance a "DIY" kit per se. But I hope I can share some insights.

I think the hardware part of the FI is the easiest. Well, that is after you have done the theoretical work behind what IC size, piping, pressure loss etc, given the characteristics of the compressor. If you can find a compressor map for the compressor, you can decide the boost you want to run, along with the air flow rate that will be provided.

Earlier on, I was running a piggyback system called ASAtronic and a RRFPR. ECU was stock. I actually had Dinan Stage 3 but that has to be reprogrammed back to stock. Reason is simple. The Dinan's engine software that I had was not programmed to run with a FI setup.

The ASATronic is nothing more than a pot for the MAF signal. I have been running this setup for a few track events. Then upgraded the injectors to 21# and now I am running a fully remapped ECU with 24#. ASATronic and RRFPR have been removed.

The ECU, by itself, can't handle a FI setup. I am pretty sure this applies to S52 as well. You can upgrade the injectors but you will also need to reprogram the mapping to take advantage of the bigger injectors.

I have heard folks using Haltech, TSI or even Greddy's E-manage as piggybacks for a FI setup. Frankly, I think the only right way is to reprogram the ECU. It will cost more but it will be worth it in the long run.

01-08-2006, 02:01 PM
How do you reprogram the stock ECU?

Also, is there any particular reason why reprogramming the stock ECU is better than using a stand-alone fuel/ignition management unit?

And a third question: if you have full control over the fuel maps, you don't need a RRFPR - is that correct?

Thanks :)

03-07-2006, 01:07 PM
1. - In this application, Uknown...some ECUs have a group/community following who have isolated the bits of code pertaining to fuel/timing tables. Typically you can then burn a new chip with the values you want. Not as easy as a stand-alone where you can alter in real time, but you should be able to get a good result.

2. - It is "better" because sometimes you loose functionality (error codes, maybe auxillary functions, etc.) with a standalone. Also, you know there are no worries with re-pinning, etc. It is closer to stock.

3. - That is correct. You would normally use the standalone with an adequate fuel system (pump/larger injectors) to deliver the proper amount of fuel for the modifications done. A RRFPR is the no longer necessary. You are doing the same thing, but in a much better, more precise way.

03-08-2006, 07:42 AM
I agree. In my opinion standalone's cause nothing but problems. Besides the loss of functionality, which in my opinion is just asking for another headache; you have to keep updating it. IMO, you are taking a "shortcut" that winds up being the "longer road" in the end.

Plus wouldn't it be easier to just have everything programmed once and have to keep going in and changing the adaptions.