2.8L M20 9.8:1 stroker build: my 323i reincarnated

[dadsbmw]

Gonna have to take my probe to this dyno!

[Digitalwave]

I'm almost certain it's a CPS, CPS wiring, or toothed wheel issue.

[betz]

I'm almost certain it's a CPS, CPS wiring, or toothed wheel issue.

This was my thought as well, BUT... it turns out it's not the case.

It's the M30 AFM.

Mr. Squid of the SSSsssssssquid apparently did not note the AFM change although I definitely did tell him. I don't fault him for it, he seems to be kinda overloaded, and plus he's been very helpful and amazing to work with thus far. I would still highly recommend him.

I swapped the AFM's with my friend's 325i and now it's like this. Perfect...

Another retune and I should be good to go. Hopefully the longevity of my engine was not affected...

[2mAn]

so did the M30 AFM help you pass smog, but isnt helping you make power? Seems backwards, but what do I know.

[betz]

so did the M30 AFM help you pass smog, but isnt helping you make power? Seems backwards, but what do I know.

The M30 AFM combined with my injectors and the bad tune were making my car run rich. Just look at the dyno. My problem before was I was running lean.

A proper tune will make it perfect, getting more power, and the increased airflow from the AFM will start to come into play. Maybe it would get about 5 extra horsepower from the AFM but if the AFM is causing it to run too rich then you'd probably be losing a lot more (because it would be burning a lot colder).

There's two other dyno runs I haven't shared, they show the car running even richer (.7ish lambda) and getting 175 max torque instead of 182.

[digger]

i dont see how running rich makes the tach go apeshit. how does it go under load?

[Digitalwave]

Yeah, I'm not really sure how the AFM could have caused the issue you were having either.

[betz]

i dont see how running rich makes the tach go apeshit. how does it go under load?

I revved it to 5900 WOT in first gear and to about 5500 in second... No tach issues whatsoever. I will continue to test throughout the week.

I figured it out because I swapped the ECU and it was revving past 5k just fine.. for the first few tries. Then the ECU "learned" and it had the issue again.

Another thing I noticed is while it's learning, it will feel much much slower, and sometimes cut fuel + tach goes shoots down at much lower RPM's. When it "learns" it's always the same RPM.

To me it seems like some sort of safeguard is getting triggered in the Motronic 1.3. Although, I don't know enough about motronic to know for sure.

[betz]

I'm thinking now what was going on was the AFM was sending a signal or voltage that the ECU does not expect/ programmed for at that specific RPM... making the ECU trip out for a second. This makes the most sense to me.

The new chip got sent out today, hopefully it rectifies the issue. Otherwise I will have to go back to the stock AFM.

In other news, I'm might be taking the E30 to an auto-x event. Going to force me to wrench on it a bit. I definitely need to do something about the brakes, I'm thinking if adjusting the brake pedal or that one adjustment at the clevis thing or whatever doesn't help, I'm going with a 750il master cylinder to improve braking responsiveness.

Past that, I think I might finally take it into the body shop. Was going to get some paint mixed to match my burgundrot, which I'm now thinking is for sure a respray (albeit a good one), replace the fender, straighten my radiator support, and align the hood. Then finally I'll have the kidneys grills in and it'll be looking like a BMW should.

Other parts I have waiting to go in at this point:
-3.46 Torsen diff from a Z3
-IE long tube headers
-Wideband O2 sensor
-Adjustable M3 sway bar endlinks
-Odometer gears
-Stereo & speakers
-New Dash
-Euro clock
-Hella smileys
-Euro front valence (for fogs)
-Front apron
-Trunk lining

Lmao, I need to stop buying E30 parts. Well at least, install everything first :)

[betz]

Jeeeeeesussssss that tune didn't help at all. My gut told me it wouldn't.. should've gone with my gut. It's my AFM.

I'm so freaking fed up with AFMs at this point.

Full standalone or Miller/ split second MAF conversion?
What's the best most cost effective solution to get rid of the damn flappy door?

[Digitalwave]

I've had both the Miller MAF and Megasquirt (MS2) and I would choose Megasquirt over Miller every time, and twice on Sundays.

[digger]

MSx PNP

[betz]

MSx PNP

Is my only option the $800 one from Diyauto? I know some other people on the forum made their own plug and play that was a little more comprehensive and a little more affordable. None of which seem to be doing it anymore. Hell, even the Diyauto one is out of stock.

I'm torn because I know megasquirt is the only comprehensive solution. Everything else has it's compromises. But I'm so close to getting something I'm satisfied with, and ditching Motronic would mean starting from scratch, installing a MAP and a bunch of other sensors, and a lot of live tuning. To achieve that OEM zen of maximizing power and drivability, its just going to take a lot of trial and error. Oh yeah, and money.

For now I'm running the M20 AFM and it looks like it has once again fixed the RPM dropping issue. My M30 AFM more than likely has a dead spot on the resistor strip wiper thingy. But the M20 AFM feels shitty to me. Pretty sure it's because I was messing with the spring tension previously. So I've finally gotten around to installing my LC-2 wideband so I don't have to be in the dark when I adjust it. I got it calibrated but I haven't programmed it for Motronic yet.

I might just hold out for now on the MAF/MAP. A certain tuner may or may not be cooking up another MAF solution... I'm anxious to see how it performs.

[Digitalwave]

You can buy an MS2 DIY assembly kit for about $400. You don't need to make it plug and play if you don't mind cutting your harness and adapting it to a more universal connector.

Adding the MAP and IAT sensors is the easy part. Yes, you will need to start your tune from scratch. But I don't know how good your chip tune is right now anyways.

To me, the MAF conversions for Motronic are major hacks, and finding a local chip tuner is nearly impossible. Yes, the M20 AFM is a restriction on a built motor, but so is the tiny throttle body as well. Maybe live with the M20 AFM for a while until you can go all-in on a standalone. Price wise, an MS2 + new tune would probably not be significantly more expensive than a MAF conversion + new tune, especially if you also did a WAR chip or something to make tuning Motronic easier.

Also, Megasquirt is not the only stand alone option, it is just popular because it is inexpensive and largely open-source. You could use a Motec, Electromotive, AEM, Haltec, LINK, ECUMaster... all sorts of options out there.

[AWDBOB]

I might just hold out for now on the MAF/MAP. A certain tuner may or may not be cooking up another MAF solution... I'm anxious to see how it performs.

I was about to comment this very thing- I am waiting anxiously as well.