abecedarian

didn't read the threads as I didn't feel it exactly necessary.
I was asking, in essence, why you thought it rediculous.

but I will be looking at the threads in the mean time.

abecedarian

the first link is about correcting backfiring and the like by using a MAF... well, a heated-wire MAF is just a succeptible to backfiring as an AFM is, except in different ways.

the second is in reference to a turbo'd engine where bypassing the AFM is a completely valid, i.e.: not rediculous, reason to do so.

in essence though, either scenario is using the stock ECU. which I suppose is rediculous for the first, but not for the turbo since the stock ecu can only trigger the injectors to deliver a certain amount of fuel. a maf or even map conversion from the AFM with different calibration and different injectors and fuel pump/pressure regulator could actually be a viable solution.

Swansen

Myself, and along with the others in those theads just felt that it is a WHOLE lot of trouble to set up a stand a lone fuel management system. Also, the first thread was about exactly what we are talking about, replacing the VAFM, as it is finicky and restrictive.

InternetRoadkill

I got a MAF from the junkyard yesterday (only $35! woot!) and spent a couple of hours calibrating it against the spare VAFM I have laying around. Through the magic of bezier curve fitting, I now have a conversion formula for operating a MAF in place of the VAFM. I just need to enter the formula into the translator.

I still need a small relay for the fuel pump control and a thing known as a DAC to supply the actual signal to the ECU. I'll need to order these from the electronic parts catalog. They should be less than $10 for both of them.

One thing I did notice is that the MAF responds instantly. As a result, it's sensitive to dirty (turbulent) airflow that the VAFM would smooth out due to its mechanical inertia. This may be troublesome. Just have to wait and see.

InternetRoadkill

Muwahahahahaahaa! The 22RE runs with a GM MAF and no check engine light. AHAHAHAHAAHA! First try no less.

It's trying to buck once it gets above 2500rpm, so there's some tuning to be done for sure. But so far, so good.

//Boy, the intake is noisy when you run without a filter.

Swansen

lol, good work, yeah, i bet that would sound pretty sweet with an aftermarket filter also, now that it would be worth it (the cone ones)

InternetRoadkill

One of the things I added was a 'fudge factor' calibration adjustment. Long story short, I fiddled with it to tune out the stumble above 2500rpm. Problem fixed.

I suppose that everyone wants to know if using a MAF instead of a VAFM makes any difference. Unfortunately, I don't have a chassis dynamometer handy to get any hard numbers. But I do have a stopwatch and a lead foot to do some 0-60 times. Here's the results:

0-60 using stock VAFM (avg): 19 seconds

0-60 using MAF conversion (3 runs): 18 secs, 16 secs, 17 secs [17 secs avg]

Woot! 2 seconds better!

But how does it feel? Well the first run it actually chirped the tires. (prolly a fluke.) It feels strong across the band all the way to 5000rpm where the auto tranny upshifts. There is a noticeable 'weak zone' centered around 3000rpm that needs to be tweaked. I'm assuming that it's because the ECU needs to be reset so it will re-tune to the new calibration curves. It goes away above 4000rpm.

There are still a few issues. First, the parts used in the translator are not rated for under-hood temperatures so I can't leave this thing installed permanently since it will cook. It's a rat's nest of wires and not weatherproof anyway. Second, I need to scrounge a new lid for the air cleaner body and modify it to fit the MAF or just go with a big aftermarket oval filter. Third, the MAF is sensitive to inlet turbulence which is producing noise in its output. This can be filtered out electronically, but it would be better to use some flow straighteners to insure a clean flow thru the MAF.

Overall, I like it. I'm not sure what I'm going to do with it. But it does work.

InternetRoadkill

Some quick pics before I break it back down again.

corax

Dude, good job . . . I guess if you really wanted to, you could run the wires into the cab and mount the board under the dash. So was that just an exercise to see if you could?

InternetRoadkill

Yah, just a test. I thought about running wires into the cab and perhaps mounting it near the ECU. But the reality is that this is just a crude prototype. I wouldn't want to leave it on a daily driver. In fact, when I tested it, I stayed within a few miles of my house and took a set of tools and the old VAFM with me in case I needed to swap it back in a hurry.

If I want to make the installation permanent, I need to have a new circuit board made that's more durable. The problem is that the setup fees for making a board and getting it assembled are not cheap. You need to make at least 10 to 20 units before the cost per unit gets to within a reasonable range. (Set up fees are about $500 plus the cost of parts.) I'm not sure what I would do with so many pieces. I only need one, so making just one for myself would be really expensive. I suppose I could sell them on ebay.

btw: That board in the picture is a lot bigger than a final unit would be. It started out in life as an evaluation board for development system. It was originally used as a radio controller for a battlebot robot.

mt_goat

Nice work! I might just add that it has been reported by Gadget that a MAF is very sensitive to changes in the intake tube diameter. I believe he discovered this when designing a "cold" air intake system for URD to sell. Seeing your pics of the prototype intake tube reminded me. Good luck with your project.

abecedarian

I forgot about this thread... lol.

anyhow... what about mounting the MAF in front of the throttle body, giving the intake duct some time to smooth the airflow? That might make it easier to mount the board in the cab also, since the harness would need to cross over. Or perhaps shrink the board a bit, epoxy over the parts and mount it in the airbox allowing incoming air to cool it?

hell, just engineer the board and get it etched, and sell it with loose parts to be soldered by the end user.

Swansen

YES, i'm sure people would buy it, if you got it working 100% i would.

InternetRoadkill

Let me answer some questions I've been getting about doing a conversion:

* What's it Cost?: I have a printed circuit board designed. It's ready for fabrication. But there are tooling costs involved to get started. The up-front cost to make boards is about $700 and that's before any boards are made or any parts get ordered. Because of this, I would have to have orders for 20 or more units to spread this cost out so that each board is reasonably priced. With a production run of around 20 units, the assembled board cost would be about $100 each.


* Can the end user assembly one from a kit?: No. The parts are very small. They require assembly using specialized tools designed to handle miniaturized components. The unit in the picture is much bigger than the final proposed unit. The final size is about a 2" square. The unit also requires that a program be loaded into it using a special programmer before use.


* What else do you need?: There is some fab work and parts scavenging required. One of the hardest items to scrounge is the connector from an old VAFM. This allows the unit to plug into the yota wiring harness without any modifications. You could hard-splice it in, but it would be difficult to go back to the VAFM should you decide to do so.

You also need to find an old airbox lid and modify it to fit the GM MAF if you want to use the factory style airfilter. You can use a big cone filter instead if you want to ditch the airbox. Some rubber couplers are required to join everything together as well.

If your truck has a resonator on it, you need to put it on a separate air filter. The reason is that the resonator tends to cough up garbage (soot and oil) back into the airbox. This would likely cause problems for the MAF.

Of course, you will need to find a used MAF sensor and a pig tail from the junkyard. The one you're looking for is from the 3.1L V6 engine used on Buicks and Chevys in the late 90's and early 2Ks. I paid $35 for mine.

Finally, the converter board will need to be weather-proofed after it's adjusted. (Untextured bed liner might actually work pretty good for this.)


Can I mount it directly to the throttle body?: Probably not. It's the right size, but the MAF is sensitive to airflow disturbances. The turbulance created near the throttle plate would likely cause the MAF to give false or unsteady readings. Because of that, it needs to be mounting where the air is flowing smoothly. Looking at the various installation positions used by GM with this unit suggests that they wanted it to be at least 12" from the throttle body.

space-junk

iTrader: (1)

and this is for the 3vze? make a sign up and im sure that you will have some people in line... heck, i would...
just wonder how it would respond to a 5* retard as opposed to the 10* stock or what most people run(12*-15*)...

InternetRoadkill

I don't know if the 3.slow uses the same VAFM as the 22RE, but it should work. The nice thing about it is that the calibration curve can be changed easily.

Jay351

Call me when its plug and play