Converting ECU to MAP Sensor

Setzer · 05-30-2005, 05:14 AM

So it's late and I get to thinking, can I eliminate the MAF? Use a MAP sensor with 0-5v output and tune the ECU's VQ settings, load maps, etc. to suit. Am I missing anything? I am thinking of all the cool things I can do like make a nice neat ITB setup

I know I have to be missing something, though I remember someone saying Nissan had a race car tuned to use input from only the TPS, so a MAP sensor can't be too far off.

exxd · 05-30-2005, 05:31 AM

I have thought about this over and over, I know its possible but may take alot of time

. Do you need an air temp sensor? As far as VQ maps go I'm thinking as long as you can figure out how the map input relates to the maf vq map values ( I'm thinking some form of test to find the proper pulsewidth with with map input). I'm not even sure if this makes sense I have been awake for way too long. Work is almost over

exxd · 05-30-2005, 05:33 AM

Now that I think about it, When I had the e-manage in the u12 det car the 3bar map and stock de maf voltages were similar, it was off about about one volt. The only problem was that when cruising on the highway it would be off 2 volts or more at times.

Setzer · 05-30-2005, 09:23 AM

Well it would require extensive time on the dyno to figure out, which I may be able to do if this is worthwhile. I'm not sure where you would be able to hook up an air temp sensor to the ecu.

coalitionSE-L · 05-30-2005, 09:35 AM

I have actually been spending a great deal of time trying to figure this out as well. I have been comparing a stock MAF to a GM 3.5 bar MAP sensor. The VQ map is simple since the MAP sensor's voltage response is linear. The trick lies in finding the formula to convert mass air flow to absolute pressure. I have been trying to hunt this bad boy down for a while with no luck. There's got to be a formula that takes into consideration the flow rate, cylinder bore, stroke, etc. to figure this out since the two obviously can't be directly correlated. Once found, it's just changing numbers around to fool the ecu after that since it is already known what voltages correspond to what pressure values with the MAP sensor. The wiring would be easy. Anyhow, the search continues!

Setzer · 05-30-2005, 05:26 PM

Interesting, it's good to know that the response is linear unlike our MAF's.

exxd · 05-30-2005, 08:42 PM

I planned on doing this but no for another 6 months. Maybe by that time it will be all figured out

Tomcat5678 · 05-30-2005, 09:24 PM

By that time Nate you could just buy the Ultimate e-manage and be done with it. High rollers like you should be all over that bling e-manage!

exxd · 05-30-2005, 09:28 PM

nooooowaaaaaaaayyyyyyy ill go with efi or autronic way before that

Setzer · 05-30-2005, 09:54 PM

No way would I ever run an eman either.

Tomcat5678 · 05-30-2005, 09:55 PM

I would go either of those routes if I had my car was a weekend/track car but the DD doesn't get those kinds of toys.

Hey Nate,

Got pulled over again for my exhaust. $153 this time.

Tomcat5678 · 05-30-2005, 10:16 PM

Quote:

Originally Posted by Setzer

No way would I ever run an eman either.

Well...Nate and I both run e-manage's now so I think we are kind of biased towards this. The e-manage has lots of potential in the right hands.

Calum · 06-01-2005, 07:55 PM

I think this is very doable, but I think I would take a slightly different approach than what you guys have in mind. I don't have time to work on anything like this, but I'd be happy to help if someone wanted to tackle it. I'd be willing to do some of the more technical work like getting circuit boards fabricated. What I have in mind would probably cost about $300ish to develope, although reproducing it would probably less than half that easily, maybe under $100 if you played your cards right. A stockish NA non-daily driver would be the perfect test bed. Basic experience with electronic stuff and C programming required, or there would be a steep learing curve.

exxd · 06-01-2005, 08:10 PM

Stock-ish NA non-daily driver, None of that fits me :/ I'll prob still try it anyways

Tomcat5678 · 06-01-2005, 09:02 PM

Quote:

Originally Posted by exxd

Stock-ish NA non-daily driver, None of that fits me :/ I'll prob still try it anyways

Hmmm....turbo daily driver......stock interior....does that work Nate?

Calum · 06-01-2005, 09:24 PM

You guys are nuts.

Let me get what I've got in mind down on paper. I've been thinking about this for a while.

Tomcat5678 · 06-01-2005, 09:39 PM

How are we nuts Calum? Nate and I are just two normal run of the mill type guys.

......or not

Oh yeah, Calum I sent you an e-mail and some money.

Calum · 06-01-2005, 09:41 PM

Got it, I'll ship on Friday. I'm working on the instructions, I'll finish them Friday night.

Tomcat5678 · 06-01-2005, 09:44 PM

That's cool, no rush on my part. Mouser won't get delivered to work until like Monday or Tuesday I think. Plus I'm off Monday so Tuesday would be the earliest I could work on it.

Thanks again man.

Very interested in seeing your ideas for MAF to MAP though for sure. I'll have to dust off the old C programming skills for this one.

Nismo87SE · 06-01-2005, 09:47 PM

I was thinking an easier way would be to have someone with a B14-B15 log their car's MAF and MAP (boost sensor) sensor outputs. Given enough data entry one could make a correlation. If you knew the volummetric effiencey then you can reprogram the ecu accordingly. However I wonder how much power is the maf holding back at all?