View Full Version : Dual Map Sensor question...help!
Tundra4x4
02-21-2009, 05:51 PM
Ok i have my dry cell installed in my truck and now i have to make an dual map sensor. My question is that how do you make one? does anyone have any schematics of a good one? Had once built were do i place the knobs for improves and or so i dont damage my engine? basically i need to know all the intel of these dual map sensors>
thanks again guys
H2OPWR
02-21-2009, 06:11 PM
Ok i have my dry cell installed in my truck and now i have to make an dual map sensor. My question is that how do you make one? does anyone have any schematics of a good one? Had once built were do i place the knobs for improves and or so i dont damage my engine? basically i need to know all the intel of these dual map sensors>
thanks again guys
I do not rember which thread but there were detailed schematics here somewhere. They just contain a couple trim pots, resistors, and switches. I was going to make my own but there are many nice ones that look great for around $30.00. There is probably $20.00 worth of parts involved in building one and 2 or 3 hours labor. For the $10.00 extra I decided to just buy one.
Larry
Painless
02-21-2009, 10:48 PM
You can find some good plans here:
http://hhoencyclopaedia.net/hho/diagrams/Map%20sensor%20adjuster%20enhancer%20schematic.pdf
It's real easy to build.
Russ.
Tundra4x4
02-21-2009, 11:01 PM
Ok that looks easy to build. ok another question how/where do i set the knobs for a good setting? I heard that you turn it till your check engine lights comes on then turn in back a hair from there...is that true? how did yall set yours?
Painless
02-21-2009, 11:20 PM
Definitely not.
You will need to find good settings for highway and city driving. You will be able to use more enhancement at highway.
A lot of people advise to 'turn it until she stumbles then back' but that isn't a good approach, especially if you don't have an EGT gauge.
Turn it small amounts at a time, drive a little distance between each adjustment, until you find a setting that meets the following:
A) Allows average acceleration without stumbling, hesitation or pre-detonation.
B) Doesn't cause the engine to stall when coming back to idle.
C) Doesn't cause a notable rise in your exhaust gas temps (hint: get an EGT).
Pre-detonation is the BIG enemy here, if you hear a sound like someone is shaking a tin full of nails under your hood, STOP!!!! TURN THE MAP BACK! This sound is basically the wonderful musical tone of your pistons and valves being destroyed over time.
Also note, adjusting MAP is *NO GOOD* if you don't have an EFIE. Otherwise, you will adjust the MAP and the sytem will go leaner, then the O2's will sense this and the ECU will adjust rich again. The proper procedure is to install HHO, then adjust your EFIE until your fuel trims are normal for your vehicle, then adjust the MAP, then GO BACK to the EFIE and make sure your fuel trims are normal again after each adjustment. A scangauge or other scan tool is a GREAT help here.
Russ.
H2OPWR
02-21-2009, 11:43 PM
Ok that looks easy to build. ok another question how/where do i set the knobs for a good setting? I heard that you turn it till your check engine lights comes on then turn in back a hair from there...is that true? how did yall set yours?
I have done tons of research here. The key word is patience. DO NOT ADJUST IT UNTIL YOUR ENGINE STUMBLES! I have access to some of the best automotive techs out there as well as some very well informed factory rep's. Today's ECU's are very smart. They have table after table to compare readings to. The one thing that helps us most and hurts us most is their ability to learn. If you make large changes at one time to the amount of fuel delivered you will have problems. You must keep in mind the LTFT (Long term fuel trim) and the STFT (Short term fuel trim). The STFT takes input from many sensors and decides how much fuel you need. It is the table that actually decides your fuel needs. It also compares it's readings to the normal amount of fuel you use under any number of circumstances. That is all stored in the LTFT. If the STFT is to lean over the LTFT over a period of time the ECU will think that there is a problem. All your work will be for not as everything will revert back to origional factory defaults. Make very small slow adjustments to any enhancer you install. Allow the ECU enough time to rewright the LTFT. Around a week of normal driving. Then make another small change and allow the LTFT to be written over again. Keep doing this while making sure that your EGT's do not get too high. You can have success this way and should not have any pre detonation this way. Your timing will retard itself along the way thinking you are running bad gas. It could take 6 weeks or two months to find the correct settings but the reward will be at the end.
Larry
Tundra4x4 I think you're going to find out that a map en. is going to play a very small part regarding mileage gains .The ecm is still going to refer to the O2s data before the map sensor data.No matter how you adjust it the ecm will most likely set code or simply dismiss the low voltage on the map sensor providing the map enhancer isn't dropping the voltage by much.
You'll be much better off with an O2 efie if you want the best mileage gains,and just keeping the map en.set very low.
And Larry is correct by saying just buy a map en. rather build one,they're very inexpensive and not really worth the trouble to build for what you save.You'd break even if you figure in the gas you'd spend just chasing down the parts or paying for shipping for them.
Tundra4x4
02-22-2009, 08:22 AM
ok thannks....i am actually building the dual efie at the moment and it seems that that is more important than the map enchancer. So i will just but the map en. and install it and take my time adjusting it. Oh ok for a dual map enchancer.....the city mode should be more lean or rich? the highway mode more lean or rich? or does it depend on my truck?
thanks
ok thannks....i am actually building the dual efie at the moment and it seems that that is more important than the map enchancer. So i will just but the map en. and install it and take my time adjusting it. Oh ok for a dual map enchancer.....the city mode should be more lean or rich? the highway mode more lean or rich? or does it depend on my truck?
thanks
Every vehicle is different regarding map en settings.For example my dodge ram hemi has a high geared overdrive trans and my city RPMs are near the same as my highway RPMs so I only use one pot. for both city and hywy.It will just take some trial and error to determine what works best for your vehicle.
H2OPWR
02-22-2009, 02:51 PM
ok thannks....i am actually building the dual efie at the moment and it seems that that is more important than the map enchancer. So i will just but the map en. and install it and take my time adjusting it. Oh ok for a dual map enchancer.....the city mode should be more lean or rich? the highway mode more lean or rich? or does it depend on my truck?
thanks
Im most cases the city mode will need to be at a richer setting than highway. All the stop and go reguires more fuel.
Larry
Tundra4x4
02-27-2009, 03:14 PM
ok i found some extra parts....and i was wondering if using two 100k pots instead of 50k would me a difference? if so what kind of difference would it make?
thanks
H2OPWR
02-27-2009, 04:16 PM
ok i found some extra parts....and i was wondering if using two 100k pots instead of 50k would me a difference? if so what kind of difference would it make?
thanks
100K pots will make the adjustment very very tricky. With 50K pots it is already touchy.
Larry
Tundra4x4
02-27-2009, 04:28 PM
what does everyone use us their pots? Should i get 25K pots?
H2OPWR
02-27-2009, 04:42 PM
From what I have seen 50K is most common. With around a 25K resistor from pin 3 to ground. Multi turn pots would make adjusting easier.
what does everyone use us their pots? Should i get 25K pots?
Painless
02-27-2009, 08:11 PM
what does everyone use us their pots? Should i get 25K pots?
I actually use 10k pots with a 10k resistor on the ground.
Tundra4x4
02-27-2009, 10:32 PM
I was going to go with that schematic that painless sent me and see if i can make it. I just want to know everything about making it and installing it. I am a college student learning and money is an issue. So if i can make it i will.....
Tundra4x4
02-27-2009, 10:36 PM
and speaking of being a student i am in my second semester of analog/digital physics. I am learning about making boards or both groups. I am mainly taking these classes so i can hopefully come up with something new for the hho community. I am in the process of making both the pwm and the efie but i with i need the dual enchancer to make it complete. So if you have any other schematics of map enchancers to let me know....thanks guys