Installed 3 bar MAP sensor on LSJ

[jrsmith]

So my 3 bar map sensor arrived (55206797)

When I had the 2 bar map sensor it was showing 92 kpa. i plugged the 3 bar in & set Linear to 329.4375 and Offset to -6.35156. The scanner is now showing 97 kpa.

I was under the impression that it should show the same kpa, so will the 5kpa difference mean I should get the sensor calibrated?


Also, regarding scaling my tune, what should I be setting the Linear & offset to? I won't be seeing any more than 25 psi as i'm using a K04. StreetDreamz on cobaltss.net said he had the 209 cell reading at 300 kPa, the 140 reading 200 and 71 reading around 100. I did read the post below that shows how they calculated the 329.4375 and -6315.56, but I don't get how i'm going to know how to translate the numbers on the x-axis (i.e. 15, 21....215).

For example, on a stock 2 bar map what voltage equals 15 and what voltage equals 215? I know that 0v = -3.3 and 5v = 270 but I don't know how the voltages relate to the actual columns.

P1 (20kPa) occurs at 0.4v and P2 (300kPa) at 4.65v. The slope is (300-20)/(4.65-0.4) which is 65.88. Multiply by five to get the linear value (which is how much range the sensor has over 5v). That's 329.41.
4.65v would be 306.35kPa of range (329.41*(4.65/5)). Subtract that from 300kPa at 4.65 and you get the -6.35kPa offset.

[cobaltssoverbooster]

according to zzperformance, and CED that part number is supposed to be the stage 1 lnf sensors. a stock gm 3 bar file i have says you should have them set to 65.89 and -6.35

[jrsmith]

I see that tune. Doesn't make sense as 5 volts is only 65.89 kpa which is very far from 3 bar. Where is the VE table for the LNF? I can't find it anywhere, was hoping to compare with my lsj

[cobaltssoverbooster]

thats not what linear is. linear is the slope of the sensor--- 65.89 kpa per volt. so at 0 volts = -6.35 kpa and at 5 volts = 329.45 kpa - 6.35 kpa = 323.1 kpa Max readable value
lnf does not have a ve table, its based on internal coefficients and can be scaled via injector offset or maf calibration only.

[TCSS07]

I run that sensor in my lsj also and use these values ... linear = 329.41 and offset = -11.25 which for me at key on is 100kpa

[cobaltssoverbooster]

the only way you can run that value is if it designates a slope considering the divisions to be 5 volts instead of 1 volt. the calibration value is 1 volt per kpa division.
if you have a 5 volt per division slope then you should be 329.45 per 5 volt change and -6.35 at 0 volts.

that could be where the difference in data comes from. all the stuff i do now strictly uses a per volt slope division. double check the ecu feature and see if it says 5 volt division.

[cobaltssoverbooster]

im sorry guys. i went into the lsj file and double checked it. the linear value is in reference to a 5 volt range which isnt standard anymore.
you would find the slope of the sensor and multiply it by 5 and thats your proper linear value in the lsj ecu. the offset remains the same but if you think its wrong check it with your local barometric pressure readings and adjust the offset until the numbers match. then from there you are set to go.

[jrsmith]

Thanks for the info. TCSS07, are you running a ve-only tune? I'm on 60p injectors, would be a big help to see how you tuned the injector offsets & spark timing.

[TCSS07]

Sorry for the delay I've been crazy busy the past few days ... I run a maf only on 80's. But I have a friends 60's (maf only also) - I tuned maf and ve on my car - so I just figured the % difference between his and mine and adjusted the ve accordingly incase his maf fails (no wideband for his tune though - friend is too cheap atm - but o2mv read 900-925 during a 2nd gear pull so its safe with no knock should be a decent starting point for you - mod based pending obviously (pulley,exhaust,cai,etc...) - this tune map settings are the factory 2.5 bar

[jrsmith]

Thanks for that. I've realized that I need some serious help to get this 3 bar map tune going, so I just bought the Level 1 & 2 hp tuners from the tuning school. I'm gonna go through everything & then do a complete tune from scratch. Not sure until I go though all the material which route i'll go. It's the one here: http://thetuningschool.com/product/g...rs-of-support/

[TCSS07]

forgot to type it in previously but the tune posted is on a factory m62 with a 2.9 zzp 3inch cai mid length header w/ cat/2.5 exh so you'd need to adjust accordingly. may i ask what mods you currently have and tune file to look at to further assist you if youd like. im running the 3 bar mostly because i just wanted to change my map sensor being original and i had some extra lnf stage sensors laying around so why not right. the tune wont care what map sensor you run being a 2.5, 3 or 3.5 bar as long as the linear and offset numbers are correct reading 100kpa at key on but with that said the the ve maxes out at 215kpa so it becomes sorta guesswork since the rpm cells continue to use the same number listed and as for me i hit that at 3k and i also cammed my lsj so for me running maf only increased the driveability of the car then with ve enabled but thats me and everyone is different. now im not saying not to tune the ve at all since you should always have a good base fueling chart just in case.

[jrsmith]

Thanks for the reponse. Back in town now.

I've got forged diamond 9.5:1 pistons, 3" CAI, K04 turbo with full 3" catted exhaust all the way back. Running the stock water-air intercooler so i'll have to go a bit light on the timing I think.

Edit: Just did another voltage read: 2 bar map: 1.75v = 92kpa; 3 bar map 1.53v = 92 kpa

If you've got a second my spreadsheet is here: https://1drv.ms/x/s!AlMbe74f1lupjddlZ5u7BLKim_hv0A
2.5bar tab is how I thought the stock voltage & slope should be. 3Bar is how I thought the new one should be based on the numbers on the forums. 2.5Bar Bosch & 3Bar Bosch are based on the data from the manufacturer. 3Bar (Calibrated) is how i'm trying to configure the offset & map sensor linear

[cobaltssoverbooster]

so you have the oem mfg slope and you have a real time data value. i suggest you adjust your offset to make the two match each other.
at 97 kpa you should read 1.568 V according to the oem slope. your 97 kpa value reads 1.74 volts which is high by 10.9%. try decreasing the offset value by that percentage (-5.66) and see if it targets closer to calculated kpa.

[jrsmith]

Ok I finally figured some shit out. I had my multimeter wired backwards. 2 bar map: 1.75v = 92kpa; 3 bar map 1.53v = 92 kpa

I updated the spreadsheet 3Bar (Calibrated) to be -10.5 and 325.26. so 92 = ~1.53v in that tab.

My question now: In the main VE table, what will the true values of the 15 kpa column header & 215kpa column header be now? (so I can extrapolate to all the other columns)

i.e. the label for the first column in the Main VE table will say 15 kpa but its true value will be ????

I know the slope is steeper than the 2 bar but i'm unsure how to proceed.

[cobaltssoverbooster]

they are what they are. there is no scaling map pressures


the sensor data you entered tells the ecu how to interpret the sensors signal voltage. the map sensor values in the ecu remain what they are (200 = 200 kpa and 15 = 15 kpa )

[jrsmith]

The slope is different, so the numbers will definitely be different. What do you think i'm doing all this work for if the numbers would be the same ?! LOL

[cobaltssoverbooster]

the only way i know of to exceed the ve table limit is to enable the maf sensor prior to the map value exceeding the ve tables max pressure axis value.

heres the problem. if you scale the map sensor then the reported sensor data is all fucked up. if the sensor data doesnt read a reasonable value then the ecu can drop out of closed idle loop control and possibly enter pe enrichment prematurely causing massive headaches.
if you leave the slope correct to the sensor then the ecu reads correctly but anything past max pressure axis on ve will become your cap point.

there really isnt a good way to scale a tune by modifying the map sensor slope data. i think you should try and search for that tuning technique outside of hptuners. i googled it a few different ways and got 0 hits regarding anything close to scaling a tune by fudging the map sensor data.
it would be wise to start considering an aftermarket ecu option say haltech elite series because it has obd2 compatibility in the higher class ones, or considering a map ecu to try and run the fuel injectors instead of the oem computer.

[jrsmith]

Ok I figured it out...it was so obvious. So here is how it looks:

kpa stock vs 3 bar.PNG

The top row is the actual kpa values once I plug in the 3 bar map using the stock (2 bar) values for map sensor linear & offset. So I can just shift the values left, maybe just do a percent reduction or something like that. I should probably adjust the linear & offset though, as the whole plug & play setup will max me out at ~23 psi

People have done VE-only tunes with the LSJ. See this guy here: https://www.cobaltss.net/forums/tuni...ng-lsj-193030/
Unfortunately he doesn't specifically lay out exactly what he did with pics & stuff.

So what I have to do next is figure out how to recalibrate all the pressure-based tables (ifr, injector latency (offsets), timing, any more?)

Any idea where I should start with this? How is cylinder airmass calculated when running ve-only?

And i'm not interested in getting a different ECM at this point. I'm going to get this up & running & then decide later whether it's worth it or not.

[TCSS07]

I agree with cobaltss i would just scale the map sensor to read properly at all times and i messed with the scaler a while back and it made the car act odd during cruising so i changed it back and if a stand alone ecm system is out of the question ... if i were you id just run maf from 3k it will just make your tune easier to deal with and using maf during wot for me tends to keep the cylinder air mass more steady rather than jumping around and it keeps the timing smoother ... ecm is also hard coded to read only up to 250 map

Cylinder air mass is just a final airflow based off the maf and ve(if used) calibration including wot afr (rich will read higher on the cylinder air axis) ... injector flowrate modifier will scale your cylinder air also ... i use a modifier of 1 since if i were to use the 1.5 or whatever accoring to the lsj injector speadsheet id go off the airmass axis

[jrsmith]

Thanks for doing that cobaltssoverbooster. Can we chat a bit about this on SKype? So I can share my screen when we talk. my skype id is joel.smith