Random Data Plots - M42 Engine Parameters Stock vs 2.1L Stroker

[bmwman91]

Maf 3 looks the best but even that is not great, but my question is was the Ecu in open or closed circuit with the Ecu. Was the engine warm?

The ECU is running in closed loop, but at WOT it ignores the O2 sensor.

But not the afm at wot, or in this case the maf.
Can you trick the ecu using the maf conversion increasing the afm voltage over that rev range/air flow range for that peak at 2000-3000 rpm.

Cheers
[/quote]

Sure, it would be easy enough to modify my MAF converter to take RPM and throttle position as inputs and have it "lie" about the air flow in that range. However, I do not see that as a very good solution and my preference is to just get a proper tune. That is hard to do because nobody local can work with old Motornic units!

[Delta]

I think maf 4 looks pretty good for the most part! Still a little off in some areas but not terrible. It could be leaned out in the midrange for sure.


You're still using the stock ecu with the MM chip correct? What are you using for the logs? I could take some logs of my car and post them with my tune to see what they're like. I may be able to help with the afr tuning aswell. I decoded the stock ecu files and have all the map locations. I've been using tunerpro and the stock ecu so far but will be switching over the MSPNP at some point.

[bmwman91]

The logger is a custom-built unit of mine (shown near the beginning of the thread). Yes, I am running the Motronic + MM chip. If you could send me an XDF and BIN that would be super helpful, assuming that the chip I have still has the maps in the same places (MarkD did the tune from what I understand). I'd like to get a look at how the fueling table looks for the stock AFM, particularly in the 2500-3500RPM range.

[bmwman91]

Dredging this up from the depths again...

I have been doing a lot of research into the stock ECU's map programming and stuff, as well as talking to SSSQuid about doing some live dyno tuning in December. For the time being, I figured enough things out to modify my WOT fuel maps and deal with the 2500-3500RPM leaning issue. Sure, enough, the maps all had a lean region in that RPM range, and I am convinced that it is precisely because the stock VAM over-reports air flow in that range at WOT thanks to intake resonance.

Here are some AFR comparisons from 2nd gear WOT pulls. The first 2 (green and blue) are with the base tune for my built engine. The second two (orange and yellow) are from today with the first round of mods I made to my WOT fuel tables. Not only are the numbers more sensible, but it has a lot more power in that RPM range. I did also make some small changes to the fueling near max 6000 to enrich things a little there too, although it doesn't look like it did all that much. It could be because my original pulls were done in the middle of summer, and today the temperature was a lot lower and the humidity a lot higher. Who knows.



Also, here is a little plot showing what all I did to the WOT fuel map. The values are converted to AFR's for ease of viewing (instead of the raw hex values from the BIN dump).




So, in a month or two I expect to have a FULL custom tune done on a dyno. This excites me, because the car is fun as hell now, and I think that there may be a fair bit of optimization in the fuel and spark tables that has yet to be done. I will definitely post up the dyno results when those are in! This also puts some stuff to bed regarding the MAF conversion...to actually have it run right, you either need a modified WOT fuel table, or a MAF converter that also takes in RPM and throttle position so as to mimic the stock sensor's non-linearities.

[bmwman91]

I just finished setting up the next stage in my logging adventures. These will be used simultaneously with the wide-band O2 sensor system to get my tune dialed in. Some remote tuning is planned for the near future, and then some live dyno tuning to get things perfected later in December.

Yes, quad EGT probes is overkill, but given the work I have put in so far, I want to see how well balanced the cylinders are. Some things I have seen in the MAF signal suggest that certain cylinders are slightly starved at some RPM's. Now it's time to see.

For reference, the threads in the stock header are M8x1.0, and as long as the threaded portion of the fitting is 11mm or less it will not protrude into the runner. The ID of the runners is ~32mm, and I adjusted the probe tips to protrude ~12mm into the exhaust stream. M8x1.0 EGT probe fittings are reasonably common, and I am thankful that BMW put standard bungs in the stock manifold. They are a bit closer to the head than is usually recommended, but since I am not planning long-term use of these, it should be fine.