A MAF to MAP concept for your review

[Gavin]

Ive been looking for an appropriate (and budget conscious) fuel and ignition management solution for my ITB project for some time now. While I have not found an ideal engine management solution for my needs as-of-yet I have come up with an idea Id like to run through the forum:

My basic problem is that in installing individual throttle bodies I need to switch out the stock MAF sensor for a MAP.

What I had thought of doing is utilizing the basic fuel adjustment capabilities of a Greddy E manage unit (the trim knobs on the base unit) to alter the output voltage of a 0 5V MAP sensor to mirror (as closely as I can) the output voltage of the stock MAF sensor. From there if I wanted to play with open loop fuel trim I could do so (again utilizing the trim knobs on the base unit) as long as I utilize the ignition harness upgrade for the E manage at the same time; in order to combat the timing problems inherent to tuning fuel addition via MAF signal in our cars.

If any-one knows of a reason why this would not work, or has any suggestions for me as to how I might solve my problem, Id be happy to hear what you have to say before I start purchasing anything.

 

[funktownp5]

This MAP ECU is the only fuel management that i know of that actually changes the

the MAF into a MAP signal.

MAP ECU

 

[MPNick]

If any-one knows of a reason why this would not work, or has any suggestions for me as to how I might solve my problem, Id be happy to hear what you have to say before I start purchasing anything.

Keep the MAF, you should make an air feed box/lid to go over the ITB anyway. The range on the MAP is not going to work well at all with the stock ECU.

Yes it can be made to run. No it will never work as well as the MAF and stock ecu.

 

[Gavin]

If I link the 4 separate runners back to a common plenum, in order to run through the stock MAF, Ill be loosing a good portion of the gains to be had in moving to ITBs. I wonder if I could run 4 separate stock MAFs in parallel (one in each of the intake runners) to get a cumulative singular MAF signal that would properly meter my air intake? Our protgs run a hot wire MAF so Id have to figure out a way to split off proper power supply to each sensor, but it could work I suppose (sounds kind of far fetched though).

Keep the ideas coming guys, I need more inspiration.

 

[MPNick]

If I link the 4 separate runners back to a common plenum, in order to run through the stock MAF, Ill be loosing a good portion of the gains to be had in moving to ITBs. I wonder if I could run 4 separate stock MAFs in parallel (one in each of the intake runners) to get a cumulative singular MAF signal that would properly meter my air intake? Our protgs run a hot wire MAF so Id have to figure out a way to split off proper power supply to each sensor, but it could work I suppose (sounds kind of far fetched though).

Keep the ideas coming guys, I need more inspiration.

Not at all. The M-3 did it this way for years. They had a very large plenum that would bolt over the ITB. It run into a Vane air flow meter. Even back when they did not know any better and removed the VAM to run Alfa N the air box was still kept. Open ITB with under the hood temps are a loss in power not a gain. Even with the air box I im still not should you will see a gain do the the throttle bodies.

 

[flat_black]

A standalone is really your best option. I'm going to be purchasing the AEM EMS from MAM in short order so I can get my ITB's going. Realistically, a MAP is the best route, as, while you are drawing in very warm air in some cases, you're going to run into the issue of runner length and efficiency. For example, my redline for the street will be 8000rpm, and I'll hit a surge right around 7000 RPM of 107% VE, thanks to pulse harmonics and so on. That's really where the gain is to be had with ITB's.

Oxygen density is great, laminar flow is important as well, as is volumetric efficiency, but N/A tuning kind of relies on all three working in tandem.

Now, all that being said... A lot of tuning for ITB's is based more on throttle position to RPM/load, rather than data gathered from a MAP/MAF, which is really what the stock ECU relies upon heavier than anything else.

I would say definitly consider going with a Microtech, Haltech, or something similar for a standalone, as with ITB's, on the stock ECU, you're going to run into a LOT, LOT of snags, and it'll probably never work properly. =/ Good luck, either way!

 

[p5T]

I hate to open this can of worms...
You could use a map sensor like the mpx5100ap and using an op amp (to change the gain) and couple of other cheap analog devices get the MAP to mimick the MAF. I have too much on my plate as it is...

Running with the MAF and stock ECU is ideal, just build a sheet metal intake plenum as all ready suggested...

The EM is only a piggyback and you would still need a MAF signal using the 'simple version', however w/ the gold version/software/map sensor you might come up with something...(but you would still have to have a signal @ idle, and you would be depending upon the EM for all of the fueling (a lot of tunning, and since the EM doesn't account for temp changes, it will require constant temp adjustments) or you could run the EM closed loop all the time of off a WBO2, but you still need to mimick engine requirements under 2K (like idle, and ac operation).

Also back in the early '90's Link used to make a MAF to MAP conversion, popular in the 944 crowd, check out there 'stuff' (or eBay)..

later....

 

[Gavin]

Lots of good points, thanks for the input guys.

flat_black, you are very right. A proper engine management system is the best way to go; I just wish they werent so damned expensive. The mechanical portion of my endeavor has been quite cost effective; but it seems as though the fuel/spark management portion is going to break my budget in a big way. Im still hopeful that I can find a less expensive solution.

It seems like such a waste to bypass the stock system (that compensates for temp, has built in O2 sensors, an air flow meter, TPS, etc.) just to install an alternate, and very expensive, aftermarket system in order to perform exactly the same function. Obviously the aftermarket system offers adjustability, and has features the stocker does not; I just wish we had the support that Honda does (ala Hondata) for better utilizing the equipment we already have.

MPNick, Im planning to upgrade more than just the ITBs, I know youre right though, without supporting mods the ITBs would be useless. The Honda boys and the Brits have been using ITBs in combination with cam, computer, exhaust, compression, blah blah blah, upgrades to pull nice power out of small displacement NA engines for years though. I cant see why we shouldnt be able do the same thing. Im really not expecting to build a break neck fast car here either. Im aware that several of the limitations of the ITB approach to improving performance will be problematic for me, but Im interested in the attempt none the less.

Does anyone have any thoughts on the multiple MAF set up?

I suppose that in all reality Im going to have to bite the bullet and buy the Haltech I was looking at originally. Im just procrastinating in hopes of finding a cheaper solution.

 

[flat_black]

Finding four 45ish millimeter MAF's is going to be rather difficult, and really, averaging out a signal from all four would be doable, but not without some sort of hardware to step down the signal, and interpolate all four, and send it out as a usable individual signal to the stock MAF input. For that matter, four MAF's of about that size are probably going to run you around 1500-2000 themselves, really.

It's more on where you want to spend the money, unfortunatly, as I've found in my endeavors. Oh, and by-the-by, using the stock ECU with ITB's and keeping the MAF /really/ doesn't work well... I speak from experience. Uugh.

Our ECU is indeed very good, but unfortunatly, the thing everyone forgets is the fact that 'very good' means it's going to adapt to what it considers running properly any way it can. It's one step away from being sentient, insomuch as it can walk right around a lot of electronics-related tricks and take back control, as well as several other types of modifications.

From that standpoint, an abrupt change such as ITB's is VERY confusing to the stock ECU, especially when what needs to be dealt with is the less gradient throttle situation, where, if you're at 70% throttle on the ITB's, that would be equivilant to being at about 110% throttle with the stock throttle body, and accordingly, the flow-to-throttle ratio is all wonky, and you'll get a rather lean mixuture, and so on. =/

I can't wait to see what you come up with, but I've found that this all is a pricey endeavor. Good luck!

 

[Gavin]

Thanks man, I'll be sure to keep everyone posted as to my progress.