MyE28.com

Hey there, new to the forum
Just out of curiosity,
For those non-SEM users, either stage 1 or stage 2
how does a car using motoronic deal with all the extra fuel using a FPR under WOT and full boost?

wouldnt the ecu have issues with running 11.5-13 AFR's under those conditions?

If its motronic 1.0 (if your is a 535i, then it is) then there is no O2 feedback at WOT which will allow whatever mixture the FMU provides w/o trimming any fuel. You will be fine. However, other adaptive motronic are not as friendly.

Unless you're running M1.3, he's right, Motronic simply doesn't care. I get a little surging sometimes at part throttle boost as the Motronic fights tries to bring the AFR back to stoich, but it's nothing terrible.

Jeremy

How does motronic 1.3 deal with it?

Motronic 1.3 supposedly makes adjustments even under WOT, so it can mess with your mixture under boost.

Standalone injection FTMFW...

M1.3 always runs in closed loop - i.e. it always uses o2 feedback to try to reach an internal AF target all using a narrowband sensor. The problem arises when, say the algorithm is calling for a 13.5:1 at WOT, if you are richening it up to say 12:1, it will see this as too rich and begin trimming fuel to reach a hard coded map of correct pulsewidth as all the NB sensor knows is rich lean or stoich. It will eventually store this as long term fuel trim and trim out all of the extra fuel you have tried so hard to add to keep from blowing up. Read through this thread and you will see russc and Oldgreene34's discussion. It will require some form of o2 simulation and a pressure switch to get the ecu to trim the fuel the way you want it. It seems that this requires alot of work which is one of the main reasons I decided to go with Megasquirt and do away with Motronic and the AFM forever.

That last link was very helpful!
Thanks for the input

doesnt seem like motronic 1.3 is the best way to go for managment :o(

ryler wrote:That last link was very helpful!
Thanks for the input

doesnt seem like motronic 1.3 is the best way to go for managment :o(

Unless you can custom burn a chip for it.

What happens if 1.3 isn't hooked up to an O2 sensor?

Even with a custom chip it sucks for boost. It only knows airflow. If you burn a custom chip for a certain boost pressure and a certain configuration, you cant change anything without burning a new chip. You would have to do just as much tuning as you would with standalone, but instead of just clicking "burn to ecu" you would have to burn a chip and physically install it.

Big PITA. And to have the AFM in front of the turbo creates tons of potential air leaks before the air gets to the engine. All of your couplers and chargepipes are moving metered air.

I can run my engine with the throttle body open to the atmosphere. There is no such thing as an air air leak when you use manifold pressure based fueling. If its getting into the manifold, its accounted for. Thats awesome. And it continuously adjusts ignition timing and fuel mixture for every boost spike and dip in the manifold.

For what it takes to learn how to burn your own EPROM and then figure out how to take apart the program on the chip you have, it makes standalone injection like megasquirt look absolutely great. I've tried to burn my own chips. I've got a Willem EPROM programmer just gathering dust because I found no way to make sense of the programming on a BMW chip. All I ever got out of that was hexadecimal garbage. I'd say my experience with standalone injection was a lot better.

I agree with Dan, Motronic 1.3 definitely isn't the way to go if you want boost. Burning a custom chip, while possible, still wouldn't be nearly as good as a standalone which would be cheaper than buying all of the required stuff to burn your own proms. You still have the AFM and limitations within the architecture of the stock DME and you will constantly be burning chips which sucks.
As for what happens if you run 1.3 w/o an o2, it will run in limp mode and try to run off of the internal maps. I never really tried it, but I am pretty sure it doesn't like not having an o2 input.

Ya I assumed the only way to go about solving ECU issues would be standalone

I've read alot about megasquirt on here, seems to be the most common approach

what about other systems like Tec3?
aside from price differences any benefits to using one or the other?

There is nothing wrong with Motronic 1.3. You get a skilled tuner to set your car up with Motronic 1.3 and not have to worry about it from then on. Adapatation can be turned off so that there is no correction under WOT.

You shouldn't have air leaks Anyway. Air leaks are either allowing unfiltered air in or pressurized air out.

Maddog wrote:There is nothing wrong with Motronic 1.3. You get a skilled tuner to set your car up with Motronic 1.3 and not have to worry about it from then on. Adapatation can be turned off so that there is no correction under WOT.

Could you please elaborate on how to turn off the correction with WOT. I'll be using Motronic 1.3 on my '89 e24 turbo. Thanks

I am slightly out of place talking about this as i've never personally tuned motronic, but I work with a tuner that does.

Adaptation is something that can be toggled on and off in all motonic ecus. It requires a chip burn or a realtime tuner to be able to do this though. It isn't something that everyone can just do.

It is a little more complicated, but also possible to keep adaptation on during cruise and off during WOT. I'm not sure that anyone has done this before, but it could be figured out and coded.

While I'm not going to disagree that it can be done and done well, I still think better results can be had by switching to standalone, especially if you don't readily have a tuner who can do this in real time on the dyno. And if you change your system, i.e more boost, much larger injectors, etc you will need a retune, plus you are still stuck with a AFM. It will be potentially cheaper in the long run as well to switch to a standalone in the early stages of the build.