First MHD Logging results (OEM BMW map)

S

stuartinzg

Active member
I finally got around to buying the MHD Logging licence for the MHD N54 app in the Android store.

After much faffing with adapters which communicate to the car properly, extension cables, OTG cables and a Micro USB to USB-C adapter, plus the Brodit setup! I can finally get it talking to the car.

IMG_20160206_190320.jpg


I thought I would see how the engine is currently operating, lots more information here than I fully understand - but plan to research more and see what it all means - also posted on N54tech to see what the tuners have to say about the running rich/lumpy idle. Perhaps the 3rd gear pull will show something. No errors in the DME, 98 ron, recent service+new plugs.

Link to all the data(I think around 15 different readings)/interactive graph: http://datazap.me/u/stuartinzg/3rd-gear-runs?log=1&data=4-21
datazap_chart_1.png
 
You can see with the OEM set up, boost is only around 10-11 PSI peak, tailing off to 5~ PSI at near redline, hence why it feels like it runs out of puff. Most maps are increasing this to 14-15 PSI with less fall off for stage 1. Would explain where all that potential power comes from.
 
I've been running at 18PSI for a while now, whenever I go back to stock it feels like the turbos have been removed!

You want to add Cyl1 ignition timing into the log too. At the moment you just have the correction logged.
Power is raised by increasing both boost and timing advance.
 
It's exactly that top rev range I wanted to enhance as it feels strangled. I wonder why the stock map tails the boost off...
 
R.E92 said:
I've been running at 18PSI for a while now, whenever I go back to stock it feels like the turbos have been removed!

You want to add Cyl1 ignition timing into the log too. At the moment you just have the correction logged.
Power is raised by increasing both boost and timing advance.
Click to expand...

Good tip, thanks. I did try to add them to the logging but it would only let me add 2 more sensors and I didn't think just one cylinder ignition timing would be enough? What about the others? Should I swap sensors on runs?

18 PSI on stock turbos? Interesting, what sort of power increase did you get?
 
Maniac said:
It's exactly that top rev range I wanted to enhance as it feels strangled. I wonder why the stock map tails the boost off...
Click to expand...

:thumbsup: One of the reasons I posted this was to give you some inspiration to see how simple it is when you do it yourself, since the advent of the Android apps for flashing. I did this logging without even touching the ECU/DME at all - zero risk and pretty interesting. Helps me to know what's going on under the hood.

I don't know why it tails off, perhaps other limitations in the car with cheaper components than the 1M? BMW may dial it back for reliability - you're the i not iS, so you will have another 40 bhp down too - with practically the same engine, that would be quite noticeable.

I have heard on the N54tech forums that we should upgrade our charge pipe (it's plastic and can leak under higher boost) and the intake as the very first steps. The OEM chargepipe can explode when older/brittle, even in stock form! These upgrades are cheap. Then it's intercooler and downpipes (race cats, the 1M has these - even though it has the same engine).

Once we get over those limitations then we have more air to play with and the IAT's won't go through the roof.

That's my theory!

Or maybe they don't want you gunning down the M3's !
 
The thing I find interesting is that the ECU is closing the throttle from 6100 rpm and up. Is this to maintain air velocity as the boost is rolled off or is it another restriction in place?
 
techathy said:
The thing I find interesting is that the ECU is closing the throttle from 6100 rpm and up. Is this to maintain air velocity as the boost is rolled off or is it another restriction in place?
Click to expand...

I didn't see that, where do I look?
 
techathy said:
The thing I find interesting is that the ECU is closing the throttle from 6100 rpm and up. Is this to maintain air velocity as the boost is rolled off or is it another restriction in place?
Click to expand...

I see it now - on all 3 runs (you can switch in the top left). That's very weird!

I wonder if it's because I have just run a throttle body reset adaptation? But I don't think so.
 
When I was mapping the Sei' my turbo started to go off-boost over the last 1500 rpm of the rev-range. Counter intuitively, closing the throttle actually increased power a bit as it maintained air velocity into the engine. Without actually getting into mapping I don't know of a way to work out what's happening.
 
Sei' ?

Yes, the more I read into mapping the more complex it becomes. Various tables and maps overlaying, it isn't just a single table/map but many many factors and sensors all coming together to provide the end result... I'm involved in complex software at work and it's very similar in some respects to an insurance rating engine (or an aggregation engine in fact, many rating values)-in that you have matrices and then inputs, which provides a value to part of an equation. But this DME has hundreds of tables, overlaying each other, with various matrices and data coming in continuously from the sensors. Everything has to operate within a "range", a bit like the range in the suspension settings - then it adapts and changes vanos, throttle, fuel, air, boost, timing, and various others, in order to pull it "back" into the range and "target".

I'm also guessing this is why drive by wire helps the engineers, because it's only a "target" rather than an absolute. They wouldn't be able to make that adjustment if it was hard wired into the throttle body.

Complex stuff when you're a rookie looking in from the outside without years of full time experience.
 
Fiat Seicento... I went so far that the OE simply ran out of table resolution so moved to an aftermarket ECU & mapped the engine from scratch.
 
Interesting project, was that when you were younger, or just a learning exercise? Do you have any info on the build/car? Did you go megasquirt?
 
I bought one of the last RHD Sei' sportings new & then kept it until about 2 1/2 years ago slowing modding it. As I live my life fairly car light; in the last 12 months, which have been heavy on car use, I've done 6'500 miles by car, almost 10'000 miles of cycling & just over 2000 miles on a motorbike. For me it started out as cost saving then replacement its were upgrades and before I knew it I had a massively modified car that I'd basically built with my own hands.

I've done all kinds of things like custom radial mount calliper setup. Had my own trailing arms made up. I've not documented my build on-line. I used a 'squirt at first then moved to a Motec racing ECU.
 
Very interesting !

Had some feedback, not sure what it means yet or what it potentially highlights?

"The surging you're feeling under WOT looks like its coming from some boost overshoot and the DME is closing the throttle to lower boost pressure under target. Has this just started happening?"
 
Basically on the first run you were getting too much boost so the ECU reduced the throttle input to the engine. This causes a reduction in torque & also will slow the speed at which the revs can increase. Once the boost is below threshold the ECU opens the throttle again torque increases & the car accelerates harder. You'll get a slight surge in acceleration, like you've feathered the throttle then got back on it again.
 
stuartinzg said:
Good tip, thanks. I did try to add them to the logging but it would only let me add 2 more sensors and I didn't think just one cylinder ignition timing would be enough? What about the others? Should I swap sensors on runs?

18 PSI on stock turbos? Interesting, what sort of power increase did you get?
Click to expand...

All the cylinders follow the same ignition advance unless the knock sensors detect a problem then a timing correction is applied to that cylinder. So you just log the timing in cyl1 and use the correction channel to check for problems.

All the VD runs I've done have come out around 360whp, so that puts me around 410bhp. That's quite conservative, some are getting 400whp on stock cars. Since I tune the car myself so am quite reluctant to push it and I'm also tapering the boost off less up top so the car feels like it keeps pulling past 5k rather than going to heavy on the boost in the midrange and having a sharp taper up top. (The stock map feels like you hit a wall at 6k!)

You are getting those throttle closures because the actual load exceeds the target load.
I've added the parameters to the log here: http://datazap.me/u/stuartinzg/3rd-gear-runs?log=1&data=2-4-18-21-24&mark=49

It's normal to get throttle closures on the stock map especially on cold days where the air density is higher. The waste gates are following a fixed base table with slight room to adjust based on a PID calculation, the PID has limited influence on the waste gates so when the engine load exceeds the target this usually means the PID is poorly configured or the base table is too far out and requires the throttle to close to reduce the load.

Logging is a much better way of gauging the health of the tune than any dyno. That's why I'm always surprised to hear of people getting remaps done at garages and driving their car without any log data for years. You could be running seriously lean and have absolutely no idea until something goes pop.

I'm not so sure the charge pipe is weak on the Z4. There's big money for vendors selling that stuff so that's why everyone is so keen to tell you it will break. Our cars have plenty of subtle changes from the 3 series engine bay and I'm yet to hear of a charge pipe actually breaking on a Z so maybe it was redesigned.

Here's a link to Buraq's Z4. Tuned by himself on stock hardware - http://e89.zpost.com/forums/showpost.php?p=18223242&postcount=64
 
You must log in or register to reply here.
Back
Top Bottom