Author Topic: MAF Converter...99% READY TO ROLL! (Read 21762 times)

bmwman91 · « **Reply #15 on:** December 22, 2006, 11:35:29 AM »

Pretty neat. For the price, it is not too bad if it was used stand-alone. Probably a lot less headaches than my MegaSquirt experience!

bmwman91 · « **Reply #16 on:** December 23, 2006, 02:04:44 AM »

Booya. I finally targeted the right area and richened it up. The car feels a LOT better, and I un-did the changes I made to the top of the flow curve so it no longer runs too rich up top. The little 2700RPM "dip" is a tiny bit noticeable, but AFR's are probably within the safe zone now! I can easily tune that little bit up now that I know exactly where to work. I will (really) do some logging tomorrow afternoon since I now have time.

After that, I just need to run extreme ambient air temperature scenarios through the design to ensure they will not excessively shift things. Then I can work on getting to the part everyone wants...assembling a BOM (bill of materials) and ordering the first production round. We are close people, VERY close! Maybe I am closer to making back the thousand $ I have dropped on R&D and countless days of work (and paying off some school loans lol)! Lol, let's just say you have not lived until you have dealt with a 22nd order polynomial at 11PM with a cold coming on!

Nathan · « **Reply #17 on:** December 23, 2006, 03:09:44 AM »

"- Would customers be willing to NOT open the throttle more than 70% under 3000RPM"

Doesnt bother me.

"Would customers be ok with ONLY using an open-element filter"

Works for me.

"Mounting and heat shielding are the responsibility of the buyer"

The cheaper the better.

I can understand your excitement. Congrats on all of your future success.

bmwman91 · « **Reply #18 on:** December 23, 2006, 05:45:54 PM »

BOOYA!

I corrected the issue! THe AFR's stay within safe bounds, and the car actually pull in the problem RPM range! Here is the log I snagged 30 minutes ago. Remember, the scale on the right is for the AFR (green)!

The previous logs looked like this:

Interestingly enough, the car actually has a lean spike right around there with the VAM. This is a shot from years ago when I dynoed my first M42 with a Conforti chip. The lean spike I experience now is less than before, but for some reason there are 2! Either way, I seem to have the problem on the run!

The addition of the velocity stack also helped a lot. The MAF output is a lot cleaner (magenta) with it on there. Looks like no dice on the air box idea! I will spend the rest of the day trying to fne tune this. Results will be posted!

nickmpower · « **Reply #19 on:** December 23, 2006, 06:18:25 PM »

how are the afrs at part throttle?

bmwman91 · « **Reply #20 on:** December 23, 2006, 08:06:25 PM »

They are good. Mileage is still the same on the highway...basically all the lower flow rates have remained unchanged. You would have to be "cruising" at like 110mph to be hitting the "correction enrichments." I have been running errands and whatnot all day in it, and it feels nice.

Still though, I need to dyno the thing and it is scary! It better put down a little more power, though I think from the get-go it was stated that this was not going to yield much there. It is intended to improve throttle response and eliminate the prone-to-wear VAM junkbox. A little extra power seems reasonable though.

EDIT:
I DID discover that throttle openings over ~70% below 1800RPM cause the motor to cut out (fuel cut). It has been doing this all along, since day of using this MAF. It is another resonance point, and might be tossing crazy values to the computer. This is one thing that has not been affected by any of my changes. People might just have to live with this one. Lol, if you want 1800RPM performance get a V8.

AL GReeNeRy · « **Reply #21 on:** December 24, 2006, 05:11:27 AM »

Quote from: bmwman91;16129

Lol, if you want 1800RPM performance get a V8.

hahah i agree

as for the rest of it...

- Would "customers" be willing to NOT open the throttle more than 70% under 3000RPM (and as we have noticed with this motor, opening it over 60-100% under 3500RPM is all the same performance-wise)?

with the 4.10 diff, i can barely get the pedal all the way to the floor before i have to shift into second... so this is definitely not a problem...

- Would "customers" be ok with ONLY using an open-element filter with a velocity stack tube (a tube which I could supply with the converter)?

YESSSSS!!!!! finally, something goes my way!!!

- Mounting and heat shielding are the responsibility of the buyer (I MIGHT look into making mounting brackets, but that would add $$ to the unit cost).

as mentioned above, the cheaper the better... ill have those before i even get the MAF anyway...

bmwman91 · « **Reply #22 on:** December 24, 2006, 12:55:20 PM »

WEll that is good to hear. I have a holiday treat for you...

I fixed it, now you CAN floor it under 300RPM. The "WOT cutoff" is now 1800RPM. OK, off to the store...then more logging.

bmwman91 · « **Reply #23 on:** December 24, 2006, 09:36:43 PM »

I think that I will call the mapping complete. Here is the catch to all of this...

The MAF takes temperature into account and naturally deals with it by design. The ECU, however, "thinks" it is the same temperature all the time. So, leaving out all the technical blah blah I had to deal with...the corrective mapping is basically perfect right now, with the outside temperature ranging from 35F - 55F during my testing. The output will "slide" on the output map with temperature changes.

Plain English:
What this means is that at EXTREME temperature differences, the MAF converter will cause some slightly rich/lean conditions. None of these lean conditions should pose a threat to your motor from what I have simulated.
- Lean Condition
This could occur if you floored in the infamous "problem" RPM range of ~2700RPM, and the ambient temperature is below 20F. Your motor should not blow up. If should in fact still be better than my original plots before I fixed the problem...you might see an AFR of up to 17:1. My only concern for the customer with this was prettymuch if they floored if there in 4th or 5th gear where it will see prolonged lean time...1st - 3rd were relatively brief.

Rich Condition
If the user is at full throttle and the outside temperature is above 90F, the engine might run a tad rich up to ~4100RPM, like maybe 12.5:1 or 13:1. Obviously, this is not a threat to the motor, it could just hurt the performance depending on where the M42's "sweet spot" AFR is.

Outside those bounds, there will still not be a threat really. Within those bounds I can more of less say that performance should be mostly the same. The "sweetspot" temperatures for this thing are 35F - 80F.

So, I have choices here (well, you guys do). I can just start looking into producing these...or I can look into interfacing this with the ambient temp sensor in the brake duct and work out like 4 different maps for various temperature ranges. I am probably over-thinking this, but I want:
a) happy customers, year round
b) to feel like I did this "right"
c) to not have to deal with ANY returns & refunds with pissed off people

It could take me another week or so to work something out with the thermistor, and not everyone had one right? Input is requested about this lol. Just putting out all the "tradeoff's" of doing this.

Anyway, you are all surely tired of reading, so here are some pretty colors.

Cruising at 55mph.

Cruising at 75mph.

Second gear pull up to 6500RPM, with what I think is the FINAL correction. I got the AFR's up top a bit richer, matching the ones from my Dyno run years ago more closely.

bmwman91 · « **Reply #24 on:** December 24, 2006, 09:53:14 PM »

Also of note...the effects of using the makeshift velocity stack. The first image was from when I had this attached to the air box. MESSY! The second one was with an 8" tube in front of the MAF, with a BIG (cough, ricer) air filter on it. Also, the lowest RPM in the messy one was was ~2400RPM. The lowest speed in the cleaner one was ~2000RPM, where the resonance is even worse! I would say that the velocity stack is an A+ idea! Now, with that said, those who will keep with the VAM...leave your little air box horns in there!!! The VAM IS slightly subject to this phenomenon, just not as much as a MAF.

Air Box, NO Stack

Cone Filter, WITH Stack

nickmpower · « **Reply #25 on:** December 24, 2006, 10:27:09 PM »

hmm, is there no way you can just tap a temp sensor into the ecu?

bmwman91 · « **Reply #26 on:** December 24, 2006, 10:46:21 PM »

Well, it gets really complicated really fast. To do an on-the-fly calculation of a 19th order polynomial that has coefficients that are decimal numbers to the -11th power (.00000000x'th) is uhmmm...yeah you get the idea. That would require a 16-bit microcontroller running at like 20MHz, and a ton of coding.

The best you can really do while maintaining reasonable coding is have various lookup tables based upon temperature thresholds. The problem is...not everyone has the ambient temperature thermistor. MOST people do I think. At first, I thought about putting a switch on that the user would toggle if it was above/below some threshold, but that seemed hokey, and would crank the cost since I would then need to machine the enclosure to fit it.

I dunno, I am tired and frankly, sick of fighting fires with this (if you are planning on being an engineer...be ready for spending 90% of the time doing that on ANY project, EVER). I know damn well I will not sell this unit with the potential error it has at the moment lol, I just need my second (or maybe seventh) wind on this. I have a spare temp sensor so I should stop being lazy and map it. I have some extra inputs How have I been managing to spend time with the family this weekend, I do not know! Working at home has its perks lol.

My goal is still to have this DONE and ready for production by the time I go back for my last semester of school...so I have 3 weeks to get my shit together! The thread title is staying lol...the converter IS 99% done if it is winter in the CA bay area!

Hope everyone else is having a good Christmas/Kwanzaa/Chanukah/virgin sacrifice/whatever! Mine has been so far (thank you beer)!

Ramblin MAn · « **Reply #27 on:** December 25, 2006, 11:46:17 PM »

Well, everyone DOES have an intake air temp sensor that hey COULD use, if they feel lucky.

The VAM has one you could scavange. You will have a velocity stack you could drill a hole in for mounting the the sensor. You would just have to supply dirrections for removing the stock sensor from the VAM and supply a plug or instructions on soddering.

Or, how much could they cost? It would probably cost you more in time to figure out what the part number is than to buy twenty.

You could also do the old "Stage I, II, III" kit thing. You know, this version is as you have it and is Stage I and comes with the ability to add the air temp sensor later via a simple plug and the owner drills a hole in his velocity stack which is Stage II.

I assume you would have to reprogram the chip? Too bad you can't put it all on a flash card that you can just yank and pop in your handy memory card reader on the computer you read this forum and write a new program to it.

bmwman91 · « **Reply #28 on:** December 26, 2006, 12:08:44 AM »

Well I believe I have the solution worked out. The thing will be able to operate from -13F to 113F (-25C to 45C) with a very slight amount of error. It will use the commonly available GM air temp or coolant temp sensor. You can stick it right in the intake boot in the extra plugged hole up by the TB. I did that for my megasquirt. A new one with connector is like $20, and "free" from a junk yard if you catch my drift. It was found on TONS of vehicles. So, that solves that.

I have the hardware all taken care of. I just need to finish up generating the various maps now.

Ramblin MAn · « **Reply #29 on:** December 26, 2006, 01:37:14 AM »

Amazing what you can do in 24 hours when you have to divide it amongst freinds, family and personal projects.

Author Topic: MAF Converter...99% READY TO ROLL! (Read 21762 times)

Nathan