So my folks have a 97 Boxster with an older M5.2 ECU in it and I've been scouring the internet for some info on how to tune it.

I've mapped out about 280 different maps by hand and I think I have definitions for about 30-40 of them.

My impression is that there is some reasonable gains to be had on these cars as the DME's were programmed primarily for ever-tightening emissions standards, performance seemed to be a distant second.

So a couple questions to start.

1) can someone confirm that I have correctly identified the WOT fueling map (11x1 @ 030D6)

2) what do those values mean, if I apply a factor of 0.007813 I get the values as seen in this pic

boxster definitions by zimbu themonkey, on Flickr

3) with respect to fueling in general, my understanding is that earlier Motronic systems used a fueling trim unit as opposed to straight lambda request. So in other words, if you want to go richer, you need to increase the value (so, say 1.10 to 1.30).

I also included a couple more main maps that I found in that pic. If anyone could chime in and tell me if my factors and identification are correct that would be awesome.

I'm just confused as to why the WOT lambda map has a decreasing curve from 1.0. If the earlier point I made about the fueling trim factors is correct (read: higher values=richer, lower values=leaner, that would mean that at WOT it would be running higher than stoich.

In any event, I'll post the read and the map pack I got from my Galetto V54, it was only a 16K read. Not sure why.

Finally, if anyone has a DAMOS for this car, I would be beyond grateful if you could share it.

PS: I plan on making my own Aurdrino based wideband sensor kit (or an inexpensive alternative) before I go messing with it. Not smart to rely on the narrow-band sensors.
 

So I think I may have been mistaken with respect to the WOT fueling.

From the Bosch documentation that I've gathered, it appears that the ECU WILL take into account MAF readings when it goes open loop and apply them to the fueling values in the WOT tables. In other words, it doesn't just blindly apply X injector pulse width vs RPM.

HOWEVER, it will ignore the O2 sensor feedback.

The remaining question that I have is this; when the car goes open loop, will the part throttle fuel trims that the ECU has learned over time be applied? Or does the ECU strictly apply it's pre-programmed table values against the MAF readings?

Given that regular elevation levels can skew the fueling values up to 15+% I would think that the learned part throttle trims would be applied. However I have not seen any firm answers either way,

Anyone care to clarify this?

Well, here's my latest $160 (or 100 Euros) contribution to this forum...

Yes, that's what it cost me to get a file tuning service to write me a file with the variocam points changed.

SO, in case anyone else ever tries to do this on their Boxster, the Variocam points are at 00FFF and 10000 respectively on the 16K read that I posted up. Stock, they're 128 and 128 decimal values.

What pisses me off is that I suspected that those were the points, however it makes absolutely no sense to have two identical switchover point values. I could see if maybe it was 127 and 128 (or 5080 RPM start and 5120 full switchover) but why on earth would they just have it at 5120/5120 RPM!!!!

Anyway, for the record, it IS worth noting that changing the switchover point a little earlier (in my case it was 4600 RPM) gives a noticable bump in power between 4600 and 5120, even on the stock exhaust components.

so while I'm a little pissed off that it cost me $160 to find out, I suspect than when I get the headers and exhaust all sorted out, being able to optimize that switchover point will pay MASSIVE dividends.

nice , im going to try to do this to my boxster S soon.

So I've decided to post up the tune that I'm currently using, it's in the first post.

If anyone has any suggestions, feel free to make them please.

Be aware that I haven't been able to verify the fueling via my wideband yet, but it feels stronger than the stock tune.

Well, I finally got my wideband installed and got the AFR's just about where I want them.

As it stands, I'm seeing 11.8:1-12.1:1, Ideally I'd like to see 12.5:1 and I'll probably tweak it until I do.

With all that said, were there any gains to be made from tuning this engine YES!!!

On the very early (mid 80's) DME's the programming on the US models was so biased towards emissions, cat converter longevity and economy that a reflash on an otherwise totally stock engine is worth about 10-15 WHP.

I've added about 6-7 degrees of timing and richened up the AFR's. I also recalibrated the load points and enrichment factors to get more fueling, faster and with less throttle input.

Unfortunately I did not get a chance to measure the AFR's on a completely stock setup, but based on the stock maps and the precent changes I made, I STRONGLY suspect that 1) the engine would stay in closed loop (i.e. 14.7:1) without anything short of putting your foot to the floor and engaging the kickdown module (mine is a tiptragic).

Now, at least when I go about 3/4 throttle at 3000-4000 in D, enrichment kicks in, AFR's go to high 12 - low 13 and you can feel the car start to make torque, whereas it the tacch would ordinarily just crawwwwlllllllll upwards.

As some people know around here, tuning a naturally aspirated engine is not just about absolute gains. Outside of cruising, Transient and part throttle driving make up literally 90% of dynamic engine conditions. So improvements in those areas (which don't show up on a dyno) are CRUCIAL to how the car responds in the real world.

I took some video of 0-60 runs and it looks like the car is now doing 0-60 in about 7.5 seconds which is exactly the times what Porsche and various magazine testers reported the stock 1997 tiptronic Boxster at SEA LEVEL.

I took note of the ambient conditions today and when the footage was taken, this was at 25C ambient, 41% humidity, 0.891 Kpa (3500 ft) AND incredibly hazy from forest fires in the neighboring province. I punched those numbers into a D/A calculator and it came out that the air percentage was 81% compared to the conditions and corrections used for the stock car's 0-60 times.

Soooooo, what does that all mean? Well, the stock car makes 200 HP at ideal (100% air). So between the decat, CAI and tune, I'd say she's putting out roughly 235 CHP in corrected figures.

While this next statement is completely speculative, in similar situations, my experience is that of that extra 30-35 CHP, the tune is probably worth about 10-15 CHP.

Again, I'm not presenting these figures as gospel truth. However, based on how the car feels now vs when it was bone stock, they seem to be reasonable.

PS: I posted an early version of my tune and I'll leave that one up. However, based on how much work went into this, I really don't care to post my final tune for just any lazy asshole to call his own. If you're interested in tuning your own boxster, PM me and might be inclined to send it off to you

cw testers are not defined properly. i am also a bit unsure about some of your others, just based off knowledge of how other m3 and m5 files are organized but maybe this m5.2 file is a bit different. the testers are for sure not organized as you have them listed.

you also have a gap at 15DF, i know what these few bytes are.

Well, I got rid of the stock muffler and am now running a catless exhaust, straight through mufflers ending in an X pipe.

Sounds MEAN AS SHIT!!!!!!! lololol. It also looks like I've picked up about another 8-10 g/sec airflow by eliminating that massively restrictive stock muffler.

I think with a set of headers, this is gonna be a legit 250 ish HP 2.5L.....