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map sensor settings?
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spam Offline
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Post: #1
map sensor settings?
I installed the HHO generator (31 plates) dry cell - EFEI - MAP voltage regulator. Currently the cell is pulling 25 amps at idle.

I did some searching in the history but couldn't find a clear/simple answer to my question regarding the MAP sensor voltage setting.

I bench set the MAP regulator to 5 V and installed.

Turned on the 1997 dodge ram 1500 w.5.9L engine. Map sensor at idle is 1.8~2.3V (nominal 2). When the MAP voltage regulator was turned on (5V) the engine ran very rough and then died.

So the questions are:

Is it correct to set the voltage at 2V for the MAP voltage?
Or set it at the normal voltage at highway speed?
Or is there some other value?

Thanks

Spam Sorenson
07-27-2009 02:01 PM
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colchiro Offline
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Post: #2
RE: map sensor settings?
Hi Spam.

I have no experience with your vehicle, but on any vehicle that has a map or maf mod AND an efie, needs to have all modded sensors set to a low level and leave most of the work to the efie. As an example, a modded air temp or coolant temp sensor is normally set to be only 10 deg F warmer than stock. Your map sensor should be set similarly, just a bit lower than stock, just enough to tell the ecu it's ok to go a little leaner. It sounds like you have that baby cranked waaay too high. Wink

More info on modding sensors in my Tuning for Mileage link.

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
07-27-2009 03:56 PM
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spam Offline
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Post: #3
RE: map sensor settings?
Rick,

Thank you for the response. I read your tuning guide before I started. It is a very good place to start, perhaps the best, (I read a bunch of poorly written bad info as well). Well done, it is both accurate and simple. Thanks for that, you obviously put in a lot of work.


I took extensive records from my sensors before I began the installation. load, small load, idle, Highway etc. 2k rpm, 3k rpm 1k rpm etc etc.

The question is, when running the HHO with EFEI and MAP should I adjust the enhancers to create as close a output match of the original readings as possible?

With MAP, O2#1 and O2#2 readings (without HHO) I can do that. Or is there a more optimum process for settings?

SS
07-28-2009 05:09 AM
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spam Offline
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Post: #4
RE: map sensor settings?
Follow up, in your tuning for economy you have these steps:


1- Verify the vehicle is in good working condition
2- Install your mileage device(s)
3- Lower your lean-out limits
4- Adjust your air/fuel mixture
5- Adjust your ignition timing
6- Readjust your air/fuel mixture

On my aspirated 1980 TR8 and XKE that is easy. I can rip them down to nuts and bolts and reassemble. even with the jag timing s a weird place.

But on a computer controlled unit step 5 (as mentioned on your page 6 next to last "MAP" paragraph) is not explained. Particularly when timing is computer controlled as a function of MAP sensor

I spent 10 years as a computer engineer, not a programmer, and can hag a scope and read it. but even then, we had manuals that explained circuit function and expected voltages/frequencies etc. I don't have that knowledge or detail for ecu. so tuning timing is not as easy as changing springs and weights in a mechanical distributor.

Thanks

Spam
07-28-2009 06:44 AM
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colchiro Offline
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Post: #5
RE: map sensor settings?
First, it's my link, but not my document. I believe it's easier for people to find these documents if I link to them and easiest to find if I say they're in my signature (or shortened to "my link"). Wink

The idea of Tuning for Mileage is to do what you can, possibly starting with the easy stuff first and progress as far as necessary to get results. I agree, many newer vehicles just use an anti-knock sensor for timing, making it difficult to adjust that.

Map and maf sensors report engine load to the ecu. By returning a slightly elevated temp (air and water) and slightly less load, you're indicating to the ecu that a slightly leaner mixture is warranted. By tweaking many sensors by small amounts, you should be able to get results, without causing any problems.

If you have a maf/map mod and use it at a high setting on the highway, you soon start throwing codes at low speeds. That's one major reason I like to have it at a low setting and leave it there (or not use it at all). It's difficult to throw a number on it, but it's my opinion that it should be within 5% of a normal setting.

The o2 sensor has the final word and is the king of the sensors so it's best to use that for adjusting your mixture. A good place to start with that is about 200 mv dc for a narrow band efie or around "2" for the wideband and establish your new mpg. I prefer to use the vehicle for at least 100 miles before adjusting it again. It takes a while for the vehicle to adjust to the new changes.
You've gone too lean if one of the following occurs:
no gain in mileage
loss of power
CEL (check engine light) or other driveability issue.

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
(This post was last modified: 07-28-2009 02:11 PM by colchiro.)
07-28-2009 02:10 PM
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spam Offline
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Post: #6
RE: map sensor settings?
Yes I printed out your document and used the diagram to build the Map voltage regulator.

Does the MAP voltage regulator/enhancer vary the voltage from normal? I mean can I set it at say 5% below idle say 1.8 for a normal idle of 2 and it will keep the adjustment across the input range? or is it set and stays there. In that case wouldn't a simple potentiometer do a better job?

thanks for the good info.


SS
07-28-2009 02:20 PM
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colchiro Offline
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Post: #7
RE: map sensor settings?
When I say 5% it's my estimate. I could have easily said, "a low setting". Either way, you'll just have to use your best estimate, based on the type of sensor you have.

The ones I've seen respond to a simple pot (50k linear taper, 5w wirewound, about $5 from your friendly neighborhood Radio Shack). See if you can find your sensor in my Wink Autoshop link, under "air flow" sensors. If it's a simple voltage type, then you should be able to use a pot. See my Toyota sensors link for a simple resistor-based maf/map mod. If it's frequency based, you'll have to wait for Mike's new mod (about 6 months I think) or do without for now.

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
07-28-2009 02:42 PM
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Post: #8
RE: map sensor settings?
thanks
08-04-2009 04:30 AM
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