Baby E30 M3 (318is, S/C)

[Artem]

Hey yall, I am attempting to get my ol trusty 318is to perform on the level of an M3, I noted the main differences besides the obvious such as the body were obviously higher power output, bigger brakes, bigger wheels, and the 5-lug hubs, from what I gather so far. I already have a S52 swapped 318TI, so I'm ok in that department, and I want to experience as close to an M3 behavior as possible (since they became unobtanium lately), so I'm hoping to get the power of the motor up by about 50HP or so with relatively low boost, aiming for 5-7PSI. I would like to keep the boost low, to keep the engine as stock as possible (really dont want to touch the engine at all). Anyway, I also got a few upgrades for the car besides the aforementioned kit to get it to ride more sporty. They are H&R sport springs, bilstein sport shocks, Ronal LS 15x7.5s, and a club sport steering rack out of an E46, and a 370mm Mtech II steering wheel (albeit with a horrible rewrap job by yours truly).

Anywhoo, my biggest question mark here is the engine power. I'm working with a company making low cost supercharger kits for the M42 engines over in Germany to get their kit working on an E30. So far I've got a 1995 318ti engine in it, with all stock E30 intake + exhaust, but all the accessories are run with a serpentine belt off the TI, which will be including the supercharger.

My plan for the engine is to do the following:
* Connect my Innovate Wideband/Boost/Oil Gauges
* Install Bosch 785 S14/Volvo 850R 30# orange injectors
* Modify the fuel map ratio to account for the bigger injectors (on the EEPROM)


My question is - I'm new to the whole tuning and screwing with the fuel maps thing - last time I had a stock M44 on my 318ti before the engine swap, I ended up putting a Downing atlanta kit on it, but I used a RRFPR with it, AND 30lb red top injectors, and a midnight tuning tune on the ECU (After actually looking into all those things again, I realized that was not the way to do it at all...)

What would you guys recommend I do/read? I am assuming if I put the gauges and injectors in, and modify the fuel map, the stock ECU should be able to cope once I slap the SC unit on, but am I completely off base here?

Thanks in advance

[bmwman91]

I would reach out to Sssquid Tuning about the remap. They can do remote tuning work if you have some basic data logging capabilities, such as WBO2, RPM and boost.

The tuning part is not as straightforward with a forced induction conversion as it is with an NA engine when you are keeping with the stock ECU. The air flow meter will still let the ECU compute the right amount of fuel assuming stock injectors, but obviously that may be changing. On top of that, the O2 signal will cause the ECU to keep the AFR very near stoichiometric at idle and part throttle conditions, as well as develop an "average" multiplicative correction factor which is applied at all conditions, including WOT. So really you do sort of need to get the fuel trim maps dialed in accurately or else that average correction value could be way off. FI engines also need to run a bit extra rich at high load conditions to prevent knock. Anyway, I could go on forever about how the Motronic works since I spent a number of years reverse engineering it, but even I ended up working with a professional (Sssquid) and they did a much better job than I ever would have. Keep up posted on the project, it is always fun to see someone do a build like this!

[Artem]

Hey I got a question for you, bmwman91, or if anyone knows - [http://www.m42club.com/forum/index.php?topic=18499.0] Thank you for documenting it all so well, bmwman91!!! But from reviewing that I wanted to check on something - my wideband sensor (Innovate MTX-AL) setup doesnt have a separate ground for the narrowband signal, would it be ok to ground the ECU O2 ground signal to the global ground and use the sensor out for the O2 positive sense or is there a danger of screwing up the ECU in some fashion? It seems like you were battling some minor offset as a result of that on the LC1... The diagram looks like it may be all going to the same place, but all the different colored items are a bit confusing.