VN Commodore ECU update

[mag]

yes amplifier on the right. could have avoided the amp had the sensor model I wanted been available in oz. the GM factory unit would be similar design with the amplifier is integrated with the sensor and different packaging. intend to add connector to wiring to match the commodore loom. fix my error with the amplifier gain, now indicating 2.76 volts for atm air pressure (14.7lbpsi). just need to trim the amp gain for 2.45 volts.

[delcowizzid]

looks good hope you get some good results cheap way to get a 2bar

[mag]

2 bar map circuit attached. not complicated. 20k resistors set the gain. output now 2.54 volts at 1 bar. if necessary can change gain by changing both 20k resistors.

[UCMatt]

Looks good.
Beware of the 1uF Tantalum cap if this circuit is going to be exposed to engine bay temperatures. They tend to short and pull the 5V rail down.

[VL400]

Well done mag, nice solution for getting a 2bar sensor without resorting to buying a GM sensor. These are the formulas for the MAP sensors used on GM vehicles if you needed to check the output of your circuit...


1Bar
MAP(kPa) = (0.369 x N) + 10.354

2Bar
MAP(kPa) = (0.781 x N) + 8

3Bar
MAP(kPa) = (1.22 x N) + 2.2

Where N = (Volts/5) * 255

As an example, if you get say 1.6v using a 3 bar sensor.....
N = (1.6 / 5) * 255 = 81.6
kPa = (1.22 * 81.6) + 2.2 = 101.7kPa

[mag]

Back with more questions. delcowizzid, have not yet tried your mag2 bin still playing around with winaldl & ASBY.

ASBY appears better suited to my engine than ARBP ie BLM around 128 when cruising at various loads, but BLM for idle is around 113. am I correct to assume closed loop does not run at idle and the BLM numbers should be ignored.

how easy is it to tune the idle for smoother running or is the poor idle more a function of the S1/2 engine.

notice that spark timing table for ASBY has 20 deg advance at most low rpm & map range where as ATFY is in 5-15 deg range. assume that as this area of timing table is not likely to be used in normal driving it is not really important what values are used.

still coming to terms with winaldl BLM numbers which appear to coincide for each VE table cell, yet my understanding is that the number of BLM cells, updated during closed loop running, is a much smaller number. should not winaldl generate the same number of BLMs as there are BLM cells. 16 BLM cells is a number I have seen quoted but believer some ecu codes use more. do the GMH codes compatible with the 808 ecu use a 16 cell BLM table.

[antus]

generally speaking the table in the ecu's ram is smaller than the ve table, so the BLMs work internally, but with reduced accuracy. Winaldl can do it better because it can maintain its own table of the same size as VEs and record the BLM against the correct cell from the map and rpm readings in the datastream. This higher resolution table is good for tuning VEs. I assume holden would have used a larger table, but the '808 only has 256 bytes of ram, and its chockas in there allready!

[mag]

any suggestions regarding how to improve the idle smoothness with a change of tune. am I correct that idle mode is an open loop system. is WOT power enrichment the same as the table "open loop A/F ratio vs RPM & MAP" and this is also open loop. if winaldl BLM values are meaningless outside closed loop, how do you know if "open loop A/F ratio vs RPM & MAP" or power enrichment setting are correct. is this where a wideband o2 sensor is used and its output is monitored directly to give rich/lean readings.

[delcowizzid]

the buick isnt the smoothest of idlers at the best of times.but by adjusting the ve cells it idles in you should be able to smooth it out.wot fueling is done in the open loop table it does both closed loop and open loop anywhere that is 14.7 is closed loop anywhere that isnt is open loop.to do wot fueling you need a wideband or to monitor O2 volts via aldl.

[mag]

have had some fun burning chips but as my only EEPROM has died and as removing the chip every time to change tune is a pain, as predicted by all, contemplating next step to real-time tuning. any recommendations as to best approach.

delcowizzid I was loading your tune when EEPROM failed. not impressed only got 5-10 burns. suspect willem burner interface software is suspect. have noticed at times that burner status LEDs sometimes illuminated, sometimes not when cables attached and burn application started. have usually done "hardware test" to reset everything before installing chip, may have forgotten this time. lost the free 27C128 chip that came with the burner when using this burner & recommended software. have found other version of willem burner software that appears to be a better match to my burner. prompts for link changes and shows you which ones when you want to erase, but too late now that 27SF512 is dead.