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

[betz]

It's long overdue, I finally got my hands on a Megasquirt. It's a used whodwho plug and play. Looks like I'll be ditching the AFM the easy way, hehe.

In other news, the car has been smogged for it's second time. It just squeaked by, my AFR at part throttle is not as good as WOT, the O2 has to trim it quite a bit especially when cold. Cool though that I found a friend of a friend who shrugged off my shiny headers.

I figured, with the megasquirt I can finally get my car actually perfect and finally give my O2 sensor a break haha. And eventually I'll take it to get it dyno tuned when an opportunity arises & get those extra ponies.

[2mAn]

How did you have your M30 AFM adjusted? I’ll be picking one up and plan to run it with the Mustang injectors and stock ECU. That’s how you felt it best, right?

[ForcedFirebird]

Best way to use the m30 AFM is to just load the AFM transfer function maps from an m30 ECU onto the m20. I do it all the time on turbo m20's. Just plugging the AFM in and adding 19lb injectors to compensate the AFM tables is a hack at best. The ECU still needs to learn, the Motronic resets every time the battery is disconnected, and runs like crap until it relearns.

[betz]

I have not touched my M30 AFM. It's one that was refreshed by Bavrest so I didn't feel comfortable opening it up and messing with the tension spring. At first I had Sssquid's tune on it which seemingly compensated for the AFM, but my motor ran better with the stocky stock M20B25 ECU. The mixture at WOT was much better, and after the ECU did it's learning it hovered around 14.7 in most situations, except for cold start. I am running S52 pink top injectors, I do also have an adjustable fuel pressure regulator that's dialed in to stock fuel pressure.

I agree that, on a stock M20, 19lb injectors and an M30 AFM is a bad idea. If you have a stock M20 just enjoy the stockness of it being turn key and just working like a factory motor. The potential for like 5 hp is just not worth it.
I feel like, just a weird combination of what my motor is, higher comp cammed stroker motor, with the M30 AFM, pink top injectors, long tube headers with a wideband O2 sensor, somehow worked out to work with stock lol. My AFRs don't lie, it is actually running good. I only did it because my car was having weird problems, I stuck the stock computer in and holy crap why is it running better haha.

But now, I can get it tuned proper, and yes ForcedFirebird if I disconnect the ECU, my motor does strange things. I usually get one big miss, the O2 sensor seems to restart(?), then my car is mostly fine from there. Yeah... I'm thinking moving to a megasquirt is a really good move.

[2mAn]

Im basically collecting parts at this point, and normally I wouldnt be hunting down the M30, but after reading this thread and seeing the smoking deal one was offered to me for, Im going to buy it.

[ForcedFirebird]

The stock m20 ECU is actually better then people give credit. Sure, it's old tech, but in reality the m20 (and m30) are stupid simple engines. They only need to trigger the coil ground to fire the plugs and a batch fire injectors (just a pwm duty cycle) on the mechanics side, and be able to decipher oscillations from the CPS.

It's the aging flapper door type AFM that is causing issues 30-40yr later that people hate, buy in reality I was adjusting track wipers in them 12yr ago, and they wake right up.

[AWDBOB]

Glad to hear you got a MS setup. Are you staying stock ignition?

[betz]

The stock m20 ECU is actually better then people give credit. Sure, it's old tech, but in reality the m20 (and m30) are stupid simple engines. They only need to trigger the coil ground to fire the plugs and a batch fire injectors (just a pwm duty cycle) on the mechanics side, and be able to decipher oscillations from the CPS.

It's the aging flapper door type AFM that is causing issues 30-40yr later that people hate, buy in reality I was adjusting track wipers in them 12yr ago, and they wake right up.

I agree completely however this is also what has held me back from going to a full standalone for so long. I tried getting tunes, I got a wideband, I tried installing Sssquid's Alpha MAF conversion, tried many different AFMs, tweaking AFMs. It just seems the cold hard truth is my engine is too far from stock to ever be completely perfect on the stock ECU. There is also an approximately 0 chance someone in California can dyno tune with my stock ECU and burn me a perfect custom chip.

It's not the modern electronics I'm after, it's the fact I can tune or get this tuned to reach absolute perfection. And I feel I will learn a lot along the way as well.

AWDBOB I have no plans on doing coil on plug or wasted spark at the moment, if that's what you're asking. But for the future, who knows :)

[AWDBOB]

Yep, exactly what I was asking! Awesome, I'll be following along. I'm going to do stock ignition for now as well with my motor, hoping it holds up with some colder plugs.

[digger]

stock igntion, and batch injection is absolutely fine for the vast majority. It's a great place to start, nice and simple.

[betz]

I've confirmed the megasquirt I've received is working, got it connected to my computer and it has started my car.. albeit very very poorly.

I chalked it up to the mess of base tune vs firmware version, as when I loaded the base map from here: http://www.megasquirtpnp.com/mspnp2_maps.php
it gave me a ton of errors. Now I'm looking at either getting firmware version 3.2.1 or 3.3.1a so I can properly load this base tune, but looking at archived firmware versions, I did try 3.2.1 but the signatures or something doesn't match on tuner studio... http://www.msextra.com/downloads/arc...ive-firmwares/

Anyone know a good solid way to start this out? What firmware to load / what base map to load? I'm thinking at this point I'll go with the 3.3.3 firmware with the 3.3.1a tune, and then if it gives me any errors I will have to sort through them. Either that, or just load the latest firmware and do the same thing.

Also wondering if these base maps take the intake air temperature from the AFM and then use the built in MAP. Or if it's actually a necessity to install the GM IAT. I was planning on doing that, just not right away.

Update: Got the megasquirt on 3.3.3 firmware, loaded 3.3.1a tune, and a bunch of warnings popped up again, but it at least it loaded mostly. I then realized looking at the dashboard of tunerstudio... my MAP was reading 152 kPa when reading atmostpheric pressure. Atmospheric should be 101 kPa of course. Checked my MAP calibration.. saw there was a drop down menu for the sensor type. Popped open the whodwho and it's using a MPX4250 MAP, which was not the sensor that was selected previously. Changed that bad boy up and now my E30 runs pretty good on the megasquirt! Biggest issue is the tach output seems to be scaled incorrectly. But it idled and revved well.

I also contacted whodwho to see if I could get a hold of his base map. It's a shot in the dark, but if I could get a hold of that I'd be golden, seeing as it's also on version 3.3.3 I could load it very easily.
But where it sits, I could start tuning it now even, so I'm pretty relieved it seems everything is working out with this megasquirt. Next step... set my wideband to send the regular wideband signal, and for megasquirt to receive them, so I can start logging AFRs. Then start tuning!

[betz]

Alright, my car is running pretty well on the megasquirt now. GM IAT installed, no more AFM. I definitely still have some issues though.

Mainly, it seems sometimes I am getting an oscillating idle. My closed loop idle is not aggressive at all and the stepper is pretty much at a fixed position. But my AFR, MAP kPa and my RPMs are all oscillating together pretty bad. I know it's not the idle cus it will oscillate when I hold it at 2000 RPM even. I'm thinking I have a vacuum leak, or just my VE table is out of whack. I think the engine should be pulling more vacuum though- it's right around 45 kPa when I'm thinking it should be closer to 30.

It's odd though, because I first got it to idle well right after I trimmed up the VE's at idle. Later it seemed to get messed up after I had it autotuning at idle though I didn't even write the autotune to the ECU. I'm thinking all this stuff might be coincidental and I have a vacuum or exhaust leak. I might put the AFM back in and see if it idles on the stock ECU. EDIT: it idles steady with AFM and stock ECU.

Besides that issue though. Pulling like a freight train at WOT heheh

Here's a screencap from the log showing idle...

[2mAn]

Lets see some pics and horizontal videos

[betz]

Hahahah nah I'll do a proper video on Wednesday I think, showing off exhaust and WOT.

I am so stoked right now. The idle issue... it was the ignition. It's fixed, as far as I can tell. I flattened out all of my ignition timing near idle and retarded the heck out of it, advanced it below and retarded above so that it funnels it into a smooth idle, and it totally worked. I figured out because I noticed the ignition advance was fluctuating with the idle. I never knew the ignition could have such a pronounce effect, and shoot I had tried to keep the ignition table close to the base map. Eh well. That was fun.

Ugh god damn the car is so awesome right now. This was a great move. I wanna put this thing on a dyno again. Then... /thread. :o

[digger]

Ignition to control idle is thing. If you imagine using a butterfly or other valve to control airflow there is a lag. Ignition is as instantaneous as it gets but the range of adjustment is limited using ignition so still need to have butterfly setup correct. Also don't want too much heat out exhaust with excessive retard