so if you hook in the 2 bar into your manfold, your 5v reference should be able to work up to 14.7 lb right? then why cant you modify that signal to fit your needs with hpt?
Im sure it has something to do with hpt not understanding the 2 bar but I could be wrong
also how do the SC guys get away with just pluging this thing in, I know I missing some key point here.
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boobs now with Riboflabin"
you could hook up the sensor fine, and hpt could monitor it fine, problem is there's no table in the ecu to reference that signal and utilize it.
Yea the SC reflash actually changes some tables to be map based instead of tps based, and lets the ecu know 5v = 14.7spi like shifted said
2000 Camaro V6.
| SLP Loudmouth | CAI Intake | HID's |
Shifted wrote:It outputs the same voltage range, but the ECU understands that 5volts = 0 vacuum, not 5 volts = 14.7psi of boost. You can try to "fake" the 2 bar although nobody I know has gotten that to work successfully.
What do you mean gotten it to work successfully? When you fake a 2 bar it still runs better than just using mechanical tuning methods right?
I know of a Ecotec running 8psi tuned with HPT and put down 227whp. That was using a 1 bar map sensor.
FU Tuning
Ok I see but once you make all your tweeks overall your tune is better off than just using the mechanical methods.
how is that possiable?
what would the 2 bar show boost voltage at? thoe boosted cars in gm arsenal still use a 5v reference right?
or do they run a higher voltage in order to keep a broad rage of ve selections
Im trying to figure out waht the difference is in pcm understanding the map sensors.
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boobs now with Riboflabin"
Its the same voltage....
-14.7psi to 0psi (full vac to no vac, 1 bar sensor) is 0 to 5 volts
-14.7psi to 14.7psi (full vac to 1 bar, 2 bar sensor) is 0 to 5 volts...
So at 2.5 volts, the 1 bar is saying "I'm at -7.35psi of vacuum", but with the 2 bar sensor, its saying "I'm at 0psi". The stock computer sees the voltage and changes that into a position in the table, so on the 2 bar sensor, even though you are at 0psi, it would be running the timing algorithm (and on the 97 the fuel) for -7.35psi, way lean...
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so how would i tune my S/C 2004 eco without a 2bar, but yet using what i already have..this @!#$ just confusses me..lol
Built&Boosted moar
04 Cavalier Turbo r.i.p my baby
2nd place 2009 GM tuner bash qwick 8--holla
Hey Shifted I spoke to you before about getting your modded GM/SC reflash for my 2000 Z24 turbo setup and after reading this post I have a few questions for you.
I finally got my HPT Pro but I'm waiting for the engine to be finished, anyway here's a rundown of my setup I don't mind paying for a custom tune.
Built 2.4 bottom end with Eagle rods, Wiesco pistons 9.3 scr, race preped new stock crank, billet main caps ARP head & main studs, 2.3 oil pump & windage tray, custom 7qt oil pan.
2.3 W41 topend p&p 086 head, Cometic hg, extruded ho intake, W41 cams, 75mm LS1 tb, custom equal length 321 ss header, 3" dp, 62-1 turbo, Vibrant fmic, 3" Custom Tubes exhaust.
Fuel system 850 RC injectors, 255 lph Walbro intank fp, afrp, GM 3 bar map, Team Green coilpack conversion & MSD DIS II HO. Anyway on to the questions if you see or can think of anything else I overlooked please feel free to adjust or setup anything I missed, thanks.
1. Can you mod the fuel table for the injectors so I don't wash the rings out of the engine upon initial fireup and don't flood it while driving?
2. Can you mod the tables to allow me to run the 3 bar map?
3. If I buy a wideband O2 is there anyway the factory pcm can use it to monitor/adjust the afr tables?
4. Can you setup the necessary idle control or other tables so the engine will idle with the cams?
2000 Z24 5spd header & catback for now.
Shifted would my request be easier if I sent you the pcm from my car, if so I can do that as I'm not driving it right now? Please let me know, you can reach me via email at aero.coupe@hotmail.com thanks again.
2000 Z24 5spd header & catback for now.
Shifted wrote:Its the same voltage....
-14.7psi to 0psi (full vac to no vac, 1 bar sensor) is 0 to 5 volts
-14.7psi to 14.7psi (full vac to 1 bar, 2 bar sensor) is 0 to 5 volts...
So at 2.5 volts, the 1 bar is saying "I'm at -7.35psi of vacuum", but with the 2 bar sensor, its saying "I'm at 0psi". The stock computer sees the voltage and changes that into a position in the table, so on the 2 bar sensor, even though you are at 0psi, it would be running the timing algorithm (and on the 97 the fuel) for -7.35psi, way lean...
right so its modfying the map sginal to compensate for the postive pressure, by just strecthing the voltage range, and this wouldnt work if you just plug it in,
but if you can go in and change the VE values for each voltage level wouldnt it work properly?
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boobs now with Riboflabin"
Dale-
Sorry, I completely missed this post. Please email me your questions at beyerr@msoe.edu
JCavi-
In theory, it would work, except that in the majority of the model/years the VE tables are NOT MAP based, they are TPS based. This means the MAP sensor has very little to do with fuel in our cars (with exception to the 97 model year and the GM Reflashes). On top of that, even if the tables were MAP based, the number of cells is fixed, so you would lose half the resolution (actually quite a bit more than half) of your fueling table in the lower RPM's, and not have very good resolution in the upper RPM's. If all that wasn't enough, more than just spark depends on the MAP sensor, and all those tables would lose resolution as well.
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Jcavi wrote:
right so its modfying the map sginal to compensate for the postive pressure, by just strecthing the voltage range, and this wouldnt work if you just plug it in,
but if you can go in and change the VE values for each voltage level wouldnt it work properly?
Right. The voltage range is essentially stretched, and you have to "fake" the tune to trick the computer into using the new voltages as they're meant to be with the new sensor.
For VE, it's not based on MAP except I think one year as I think someone said. That limits you some, but there are ways around it. When you actually go into look at the data that really happens...you'll see that certain boost values at certain rpms correspond fairly closely with certain tps values from cerain rpms (a cell from your ve table matches with a cell from what a map based ve table would look like). However you don't have to try to figure out how these match up, and it's not going to be always perfect. But that's where your wideband tuning comes into play (which you'd be doing anyway).
Also, there is a table, i forget what it's called, but something like injector pulsewidth modifier table...and it's VAC based (which is based off of the MAP sensor), so if you're using more than a 1 bar sensor, such as the 2.5..this table actually extends past VAC into boost as well. Basically, your injector constant will be multiplied by the numbers you put in this table, so the idea would be for more boost, you'd have a higher multiplier such as (1.2-1.3), and it would probably scale down with less boost and into vac. I can show you my table if you want to see it.
For more information, check out my How To on HP Tuners and GM Eco s/c, it has info on how to fake a 2.5 bar tune, but if you're using a 2 or 3 bar, the concepts are still the same. If you have any more questions, feel free to ask.
There's another point that I rarely see mentioned. In general the computer will take a reading of the air pressure (called the BARO reading) when the key is first turned on, before the engine starts. This reading is essential for calculating air density and in turn for calculating the correct amount of fuel. During cartain times when the throttle is WOT the pcm will assume MAP is at atmospheric pressure. That's really not a problem on most N/A cars as the MAP is at atmospheric pressure during those times. But with a 2 BAR sensor on an N/A cal there's an issue. First, the key on / engine off BARO reading is going to be much lower than the pcm expects, but what's worse is that it could do a BARO update at any time, under any amount of boost, and that would throw off the basic fuel calcs way out the window. If the pcm sees atmospheric pressure similar to Denver on startup, then goes for an update and finds baro reading indicating you've actually dropped to sea level, it's going to increase the fuel delivered across the board. You could end up tuning the car around town without boost to get a good AFR then go out for a run or two under boost and now everything's too rich. If you start pulling fuel at this point you'll find everything is too lean on next restart.
Just another thought.
-->Slow
I just wired a 2.5 bar tmap on my 05 eco.. it didnt fit where the stock 1 bar goes so I pulled the manifold off and plumbed it into one of the other runners. Tuning it was time consuming but I got it to work...I am N/A right now(still have a tiny amount of fab work). But I think it runs a little funny but I'm not going to worry about it until I get my Wideband into my downpipe so I can monitor A/F
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Shifted wrote:Dale-
Sorry, I completely missed this post. Please email me your questions at beyerr@msoe.edu
JCavi-
In theory, it would work, except that in the majority of the model/years the VE tables are NOT MAP based, they are TPS based. This means the MAP sensor has very little to do with fuel in our cars (with exception to the 97 model year and the GM Reflashes). On top of that, even if the tables were MAP based, the number of cells is fixed, so you would lose half the resolution (actually quite a bit more than half) of your fueling table in the lower RPM's, and not have very good resolution in the upper RPM's. If all that wasn't enough, more than just spark depends on the MAP sensor, and all those tables would lose resolution as well.
I thought all year ecos were speed desity? whats the point of having a map sensor if its not being used? as for reasaltoution Im not so sure that it's an issue. as long as you can get the ve value close, the 02 correction should be able to compensate. for the differences. the ve is just the big nob on the tv to get you close.
as for the comment on the baro sensor, If all its doing is setting calibratoin for WOT, which is a set voltage for atmospheric, then it should be easy to just fake with a solid state resistor.
Im telling you guys theres a way around this.
"
boobs now with Riboflabin"
Jcavi wrote:Shifted wrote:Dale-
Sorry, I completely missed this post. Please email me your questions at beyerr@msoe.edu
JCavi-
In theory, it would work, except that in the majority of the model/years the VE tables are NOT MAP based, they are TPS based. This means the MAP sensor has very little to do with fuel in our cars (with exception to the 97 model year and the GM Reflashes). On top of that, even if the tables were MAP based, the number of cells is fixed, so you would lose half the resolution (actually quite a bit more than half) of your fueling table in the lower RPM's, and not have very good resolution in the upper RPM's. If all that wasn't enough, more than just spark depends on the MAP sensor, and all those tables would lose resolution as well.
I thought all year ecos were speed desity? whats the point of having a map sensor if its not being used? as for reasaltoution Im not so sure that it's an issue. as long as you can get the ve value close, the 02 correction should be able to compensate. for the differences. the ve is just the big nob on the tv to get you close.
as for the comment on the baro sensor, If all its doing is setting calibratoin for WOT, which is a set voltage for atmospheric, then it should be easy to just fake with a solid state resistor.
Im telling you guys theres a way around this.
There's not a way around this...
The Eco's are NOT speed density, they are alpha-N just like the LD9's (except for 97) and the LN2's.
The MAP sensor IS being used, just not for fuel (at least not high RPM, the low RPM VE table is typically MAP based). The resolution IS a HUGE problem, if you can't get the car to run in the low RPM's whats the point? You can't get the VE value close, thats the problem. The jump between the cells is so large that it doesn't allow you to get a decent smooth tune in there. The O2 sensor only makes compensations in the following conditions:
1. You are NOT in PE mode (basically it only corrects when you are cruising)
2. You are NOT in decel mode (see above)
This means that when you are getting on it, the VE table MUST EXACTLY be right, otherwise your fuel will be off, a lot. You've got your analogy backwards, the VE table is the driver, the O2 sensor is the "knob" that dials it in. On top of that, the O2 sensor will only compensate so far before it throws a code.
As for the startup issue, you cannot fix this with a resistor. You'd have to turn your car on with the resistor in there, then pull the resistor off while its running (and the ECU would then throw a code). Its not really a calibration for WOT either, all the fueling algorithms up through full vac to WOT use the barometric reading for fuel adjustment.
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I went from a 1 bar OEM to a TMAP and I got my car running just like normal..
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I dont understand the resolution issue, the megasquirt uses a 12, 12 and runs fine, even streched out with a two bar.
as for the baro Isnt it just checking for density of the air? and using the little nob theroy to make fuel adjustments accordingly.
but alas, If its alpha N none of it matters. unless you can switch to speed density, none of it really means anything.
just out of curiosity whats up with the one year speed denstiy thing.
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boobs now with Riboflabin"
The BARO is just checking air density, which might not be so bad if it was a one time deal. But what happens when the pcm decides to recheck air density, and you happen to be in boost at the time? Then air density suddenly looks like atmospheric plus 6 psi, so the pcm calculates that you need a bunch more fuel all the time. Now how would you correct that? If you pull fuel the engine's going to be lean when the BARO reading gets straightened out. If you leave it alone the car will run like it's not tuned right. You'd almost be better off with a 1 BAR sensor and a check valve / vent to atmospheric pressure.
I can tell you the resolution on my OBDI timing tables after switching to 3 BAR sensor sucked. From 15 to 40 kPa was gone. That's most of my around town driving. It's almost like having no vacuum advance, only rpm based advance. Gotta find the setting that works best and deal with it.
-->Slow
I am 100% with slowolej
Go back to John02's post about switching to the 2.5-3 bar and look what you're doing. You are compacting how many rows of timing advance is thrown off because you are condensing it down into 4 or 5 columns
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nah theres something missing there. your ve is just a starting point. kinda like " here car use this fuel to start off with, then go ahed nd finen tune me" . your accel advacne and your controller authoritys should throw everyting in check once you dont see proper AFR's and timing advacnces. I think your missing a paramter and the cars not correcting right.
another thing why cant you just set the BARO to read straight atmo, by taking out the senosr or hooknig up a controlled leak. it might fueck with the tuning, but you can always work around it.
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