This link is no longer any good....I would love to read the information.

Would someone send me the file?

W


Title: Detailed Diagnostic Information
Description: GM LS1 Information PDF file
Purpose: Interesting read describing the various sensors and how they work...
Location: https://ls1tech.com/forums/pcm-diagnostics-tuning/103710-detailed-diagnostic-info-ls1.html
Quick Jump: http://carprogrammer.com/Z28/PCM/LS1/Holden_LS1.pdf
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its still here http://www.hsvdriversclub.co.uk/ls1.pdf

 

also added this (^^^)PDF to my personal server... so long as I don't run too close to using up my bandwidth, I'll let it stay

Added SVO Injector tuning post

 

i dont know if there is any full write up i have done or someone else has thats out there but the IAC count and effective area table seems to be comming up a lot maybe we can add this. i think i wrote it all up in here somewhere...

 

please do, make a nice preset .cfg for it too, i have few big cam cars with funky idles coming up soon.

 

ok if i get a chance when i get home ill type it in here and ive got to get my computer online to load up the config, if not ill post up the stuff i logged and someone can make the config.

 

search and search man, most of the stuff still applies, just might be different tables

 

Added an FAQ section. If anyone has any ideas for simple 1 line questions and answers (well maybe more than 1) that are asked commonly (started because I noticed 2 threads today asking if their tune will be lost due to resetting the PCM) let me know...

Just send me or post up here something like:
Q: What type of FAQ should I make?
A: Whatever kind you want

 

Added IAT vs Temp vs Resistance chart.

 

I've read all the FAQs and stickies. Maybe it's the way the info is organized and presented but I don't feel comfortable beginning my foray into changing the program yet.
My mind works best when I get comfortable with each step in the title of this post in order.
Theory
As far as theory is concerned the goal is to get the optimal combustable mixture and ignite it at the optimal time. The old gas plus air plus spark equation.
a) Gas is the amount of fuel supplied by the injectors. This is further broken down into the size of the pipe (injectors) and the length of time they are pumping.
b) Air is the molecules of oxygen present in the combustion chamber.
c) Spark is when the spark plug fires during the combustion stroke.
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AFR is the ultimate indicator of how well the process is going so the first step would be to log wideband O2 sensor data and see where in the operating range of the engine the process is amiss.

Quote from gameover:
PCM first works out airflow, then fuel.
It calculates it has X grams of air in the cylinder (MAF/VE table), it knows it has a target AFR of Y, therefore it needs to inject Z grams of fuel. Z = X / Y
Once it has worked out it needs Z grams of fuel, it then looks to the IFR table to work out how long to pulse the injector for to get Z grams of fuel.

Speed Density
Air density is calculated from the IAT (intake air temp sensor) and the MAP (Manifold Absolute Pressure). ie Higher IAT = less dense air, Higher MAP = more dense air. Combined with information from the CKP(crankshaft position sensor) the PCM detrmines the required injector pulse.

Mass Air Flow
Under normal conditions the MAF (Mass airflow sensor) works in conjuction with the speed density system to calculate the required injector pulse. If the MAF malfuctions then the speed density system is used exclusively. The ECT (engine coolant temperature sensor) and the TP (throttle position sensor) also provide inputs to determine injector pulse width.

Open Loop
This system is used when the O2 sensors have not come to full operation temperature or they have failed. Injector pulse width is detremined by the
the inputs from the CKP, MAF,MAP,IAT,ECT and TP.

Closed Loop
The O2 sensor input is used to modify the injector pulse width signal determined in Open Loop to achieve an approximate 14.7 to 1 AFR (air fuel ratio)

Power enrichment
Fueling changes dictated by the the O2 signals are ignored. AFR is richened based on large TP changes

STFT (short term fuel trim)
Corrections to the AFR based on O2 inputs. These are not stored by the PCM.

LTFT (long term fuel trim)
If the PCM continues to adjust the STFT for an extended time period for a particulat cell in the trim table the PCM will change the value in the LTFT table cell and reset the STFT adjustment to zero. Each cell in the LTFT represent a specific engine operating range. When the engine is operating in that range the PCM looks to the LTFT table and makes the correction to the injector pulse width indicated in that cell. The STFT continues to monitor AFR and further adjusts this Injector pulse width if necessary.
Information in the LTFT table is lost when power to the PCM is lost.


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Programming methodology: There are two schools.
a) Log data on the road or on a dyno and simply bump the numbers up or down on a particular table to get the right AFR and timing. What the numbers actually mean in the tables are irrelevant.
b) Log data on the road or on a dyno and calculate the "correct" values for the cells in various tables.
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Mechanics

What are the sensors that provide the data to the PCM software so...
the software can compare these sensor values to those in various lookup tables and then provide an output signal to:
1) the injectors
2) the coils

So I would like to have an excel table which shows cause and effect listing:
a) sensor
b) what it measures
c) what are it's units of output
d) how to convert this output to meaningful information such as temperature in degrees celsius
e) what PCM lookup tables it values are compared to
f) based on this comparison, what the PCM software outputs to which device, compares to a further PCM lookup table, or modifies a lookup table.

Consensus information I have gathered so far:

1)Timing is primarily adjusted through modification of the High Octane Spark Advance table.

2)Adjusting AFR is a little more complicated and controversial in regards to what table or tables should be adjusted.
-some say to leave the VE (volumetric efficiency) table alone and adjust the MAF (MAF vs Frequency Table).
-others say to adjust everything, PE (power enrichment) , VE and MAF.

3) Everyone does agree that LTFT (long term fuel trims) are a critical indicator of how things are going. Adjusting them exclusively does nothing as they will just go back to where they were as a result of STFT adjustments. You must correct the AFR through adjustment of table values (VE and MAF) and then zero (or as close as possible with a bias toward negative which makes the mixture leaner) the LTFTs.

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Tools

Then we can use the tools, of which there is the most information on, to modify the look up tables in order generate the signals we want, when we want them, to the injectors and coils.

I am happy to accumulate contributions to the building of such a table.

 

How accurate is the injector scaling? My pcm shows something different for my 42lb SVO injectors. I have HP Tuners and I would like to know what values to change if I switched from 42 to 60lb Seimens. Thanks.

 

^^^ 42lb brand (what) to 60lb (brand what) ? Vince .... PM me the info and also make a post about it here (PCM section) .. (if both siemens .. i'd think they'd be linear... so the standard formula would work.... but would be best to post up anyways...... at your power level.... it may not be linear)

 

I sent you an email with my current settings.