Tuning a 173 with a MAF and turbo?

[ForcedFirebird]

Who says you can't tune the Motronic?

AFM replaced with a Volvo MAF...





We are still running quite rich, but think that we have it licked, just need more time to iron out the tune. I also have a home-made wide band controller (JAW) that can log AFR vs RPM that we will be implementing soon.

-John

[kamotors]

pretty cool.

[JTapper]

You can do the same with the Miller WAR chip.

[StereoInstaller1]

So hold on there, John, this is a Volvo MAF with a stock 173, boosted?

Have you already posted your setup?

My hat is off to you, Sir!

[M5wanaB]

wow, I think you should tune a chip for a stock m20 with 173 to use a MAF, I think there would be quite a market for it. I would love to get rid of the old trap door.

[ForcedFirebird]

wow, I think you should tune a chip for a stock m20 with 173 to use a MAF, I think there would be quite a market for it. I would love to get rid of the old trap door.

How about you can do it free if you have a chip burner... ;)

I could work something out if you guys are interested, there is already a file for N/A and MAF conversion posted on Tunerpro.

[ForcedFirebird]

So hold on there, John, this is a Volvo MAF with a stock 173, boosted?

Have you already posted your setup?

My hat is off to you, Sir!

It's not my car, it's the Grassroots BMW that Silence has. I will be using this on my car soon enough, blow-through, though, I like to hear the BOV :D

[M5wanaB]

How about you can do it free if you have a chip burner... ;)

I could work something out if you guys are interested, there is already a file for N/A and MAF conversion posted on Tunerpro.

no chip burner but I would love the chip. let me know, also what maf to use and is there any other modification involved??

[ForcedFirebird]

You have to solder some inside the ECU and make an adapter for the MAF.

[MonkeyMadness]

Hello ForcedFirebird,
How are you doing... You might remeber me for the 60*v6 site..
(BlownArrow):pimp:

Hey I'm in process of building my turbo project as well...
got any updates?
I found the site below I was going to use to do mine. Is yours similar?
What do you charge for your setup? :pimp:

http://www.chiptuners.org/forums/viewtopic.php?t=6349&sid=913c9888f80537fe33e8e367ebd0a5e7

Update this thread or Hit me back soon, I'm intrested in how far along you are!

[ForcedFirebird]

Hey! I didn't know you had an e30!

Yeah that's the same guy that I got the idea from (just not on that site). He is very versed in the realm of PROM tuning and electronics.

We haven't got the bugs ironed out yet, those vids and pics were just before an auto-x and he had to revert back to the old setup dues to breaking up (rich) under heavy loads and/or rapid RPM changes. Now the race car is apart to do the rear camber correction, new solid subframe mounts and a few other items.

When I have some more seat time, I will update this thread ;)

[bmwman91]

Interesting setup there.

There are a couple of pitfalls that you may or may not have worked around.

1) Air temp compensation. The Motronic takes the AFM input (m3/hr) and air temp signals to internally determine the mass flow rate (kg/hr). Running a MAF straight to the Motronic and tuning it will leave you with a tune that is only correct for the air temperature at the time of tuning. As the temp changes, so does the air density. The MAF internally deals with this by nature of its operation, but the Motronic does not know that the signal coming in is mass-based rather than volumetric. Short of rewriting the ECU source code to ignore the IAT & use the AFM/MAF signal for the load exclusively, the only other option is a dummy resistor in place of the IAT thermistor. This will tell the ECU that it incoming air is one temperature at all times, so at least the tune won't drive with air temp (MAF compensates for this itself). There are drawbacks to this, but it's better than running without compensation. If you want any further tips on this let me know. I have the thermistor's behavior mapped out.

2) Intake track resonance. From what I can tell, the Motronic only samples the air flow signal at like 100Hz or less. Combine this with the insane sensitivity of a MAF (you can easily resolve individual intake pulses of you hook a scope up to it & go WOT), and the ECU will get the fueling wrong due to aliasing (primary harmonic present in MAF signal is greater than Fsampling/2). A 100Hz sample rate would mean that the ECU can only accurately deal with the signal up to 1000RPM on an I6. Simple analog filters won't work...they will make you run lean since the MAF has a non-linear transfer function. You need an app-specific DSP between the MAF & ECU. Of course, this is slightly less of an issue on a 6 since there is intake overlap...it's a bitch on a 4.

Good work on the project though. Let us know how the MAF stuff works out & if you can get it to hold a tune!

[ForcedFirebird]

The AFM is not directly bolted in place of the AFM. There is a jumper in the circuit board and the intake temp sensor is wired in the mix. I would have to talk to the originator of the system,but he has been a great help as far as posting starter .bin's on TunerPRo's website and he has detailed instructions on the swap. I feel our biggest issue is peripherals such as the extreme light weight of the car and we aren't using the same injector value he did. Also I am not using an emulator and just burning chips doing a trial and error approach based on what little tuning experience I have on GM OBD1 systems.

It's simply going to take more seat time or getting an emulator and using TunerPro v.5 with it's newly implemented data tracing to see what blocks the ECU is reading in real-time. If only BMW had datalogging like GM, this would have been done a while ago...

[bmwman91]

The AFM is not directly bolted in place of the AFM. There is a jumper in the circuit board and the intake temp sensor is wired in the mix. I would have to talk to the originator of the system,but he has been a great help as far as posting starter .bin's on TunerPRo's website and he has detailed instructions on the swap. I feel our biggest issue is peripherals such as the extreme light weight of the car and we aren't using the same injector value he did. Also I am not using an emulator and just burning chips doing a trial and error approach based on what little tuning experience I have on GM OBD1 systems.

It's simply going to take more seat time or getting an emulator and using TunerPro v.5 with it's newly implemented data tracing to see what blocks the ECU is reading in real-time. If only BMW had datalogging like GM, this would have been done a while ago...

Interesting. Got a link to the project/thread on Tunerpro? I would like to see the wiring & stuff for this project!

[ForcedFirebird]

MonkeyMadness posted a link to it, but there's also one on ecuproject. Same guy who has been making turbo chips for the m20 for a few years ;)

In fact the GRM BMW is still using his same chip with huge injectors with the AFM tweaked, been running like that since before the last challenge, but we are ready to utilize these much larger injectors and want to have it running on MAF for the next challenge.