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MAF or IAT Sensor?
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mineraltea Offline
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Post: #1
Question MAF or IAT Sensor?
Hello all,

I've built myself a fairly decent cell that puts out a steady 2 lpm at 28 amps, but I'm stuck where most people are stuck; trying to override the ECM.

I started out by building a simple EFIE, but my 2004 Nissan Quest uses current based AFR sensors instead of voltage based O2 sensors and I saw no difference.

Preparing for a 1,200 mile round trip to N. California from Portland I decided to do an ECM reset, but still no change. Before heading back to Oregon, I decided to place a 50k ohm pot with a 3.3k ohm resistor to ground on the IAT sensor wire. Doing this caused my mpg to go up with no noticeable performance drop.

Then finally today I placed a 50k ohm pot on the MAF sensor wire. The timing dropped when I turned the pot, and I could just about get it to stall, but driving around was tough as all the power was gone, even with the HHO on. And the mpg dropped substantially.

So my questions are; How are people using the MAF enhancer? Are they combining it with other electronics or solely alone with the hho? Why does the performance drop so much?

Second, how does adjusting the IAT sensor result in such mpg increase with no noticeable performance drop?
12-01-2008 09:23 PM
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AlexR Offline
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RE: MAF or IAT Sensor?
An extra 28 amp load on a minivan? Your alternator isn't going to last long. Try to reduce your load and make less gas. you're making more than enough. On the other hand you won't know what your ideal gas output is until you do some more sensor mods.

The reason your mileage went up with the IAT mod is that you told the ECU your intake temp was hotter than actual. This retards your timing. BG makes your fuel burn faster and so retarding your timing is usually required.

Your MAF sensor. You're adding too much resistance. Is your pot in series with your MAF signal wire? Or does it go from the signal wire to ground? One would think it's all the same, but for me the pot between the signal wire and ground seems to work best. If you do this go to the ground of the MAF sensor, not vehicle ground. Vehicle ground and ECU ground are different.

Use a multiturn pot, it will give you more fine tuning. You should just turn it until you notice a drop in performance then turn it back a bit until your power is back. Use that as a starting point and fine tune from there.

I hear a rumor on this site that Mike has an EFIE for the AFR sensor on the way, one of those will make your life a lot easier.

Alex

Cool Flame, LLC
http://www.cool-flame.com
12-02-2008 02:41 AM
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colchiro Offline
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Post: #3
RE: MAF or IAT Sensor?
It's no rumor. Mike's AFR should be available by the end of the month. Email Bruce to be put on the waiting list.

I agree with Alex. Try to get that 28 amp load reduced. Did you wrap your cell?

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
12-02-2008 04:20 AM
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mineraltea Offline
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RE: MAF or IAT Sensor?
Concerning the 28 amp load; I figured with a 130 amp alternator that I've got a little to use. But I'll adjust the electrolyte to pull less. I guess I really only need a little over 1 lpm.

For the MAF pot, I didn't ground it at all. Pin 1 - from MAF, Pin 2 - to ECU, Pin 3 - null. It does what it should do, retard the timing. Perhaps I had it too far during my test. But how does an overly retarded timing result in such a mpg loss? Conceptually I figured it would be a balance between losing performance for gained mpg. I'll try your method for finding a proper starting point.

Colchiro - what do you mean by wrapping a cell? I built a cell similar to the Smackzilla cell. Acrylic box, with dividing walls, 7 cells each at 2v and placed it in the back of the van.

Thanks you guys!
12-02-2008 10:21 AM
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AlexR Offline
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RE: MAF or IAT Sensor?
mineraltea Wrote:Concerning the 28 amp load; I figured with a 130 amp alternator that I've got a little to use. But I'll adjust the electrolyte to pull less. I guess I really only need a little over 1 lpm.

For the MAF pot, I didn't ground it at all. Pin 1 - from MAF, Pin 2 - to ECU, Pin 3 - null. It does what it should do, retard the timing. Perhaps I had it too far during my test. But how does an overly retarded timing result in such a mpg loss? Conceptually I figured it would be a balance between losing performance for gained mpg. I'll try your method for finding a proper starting point.

Colchiro - what do you mean by wrapping a cell? I built a cell similar to the Smackzilla cell. Acrylic box, with dividing walls, 7 cells each at 2v and placed it in the back of the van.

Thanks you guys!

With a 130 amp alternator you may have the capacity to pull 28 amps. I'm surprised to hear of an alternator that big on a minivan. I guess with the multiple TV screens, DVD players, GPS, heated seats, that it might be necessary. If you have, or can borrow a clamp on ammeter you can tun on most of your electrical loads and you may have the extra capacity. Try your worst-case scenario, lights on, heater on high, radio on, windshield heat on, etc.

I still think your making too much gas at this point.

Your primary sensor to control timing will be your IAT sensor. Use the mod on the MAF to reduce fuel flow. The MAF does have an impact on timing, but not like the IAT.

If you are losing performance you wind up pressing further down on the accelerator to get the same power and you end up losing mileage. It seems counter intuitive, but that's how it works out.

You shouldn't lose performance, possibly gain some.

Alex

Cool Flame, LLC
http://www.cool-flame.com
12-02-2008 10:58 AM
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colchiro Offline
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Post: #6
RE: MAF or IAT Sensor?
Wrapping cells assumes you have multiple plates surrounded by a bath of electrolyte. Wrapping them means surrounding the plates with insulation (usually heat shrink) to reduce stray currents, decrease current and heat and increase efficiency. Smacks covers this briefly in his installation pdf.

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
12-02-2008 01:44 PM
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