Tuning Info

[Gelf VXR]

Some info i put together from the web

http://i5.photobucket.com/albums/y164/andysa1966/41_image_airfuel.jpg

http://i5.photobucket.com/albums/y164/andysa1966/exhaustmixture1.jpg

http://i5.photobucket.com/albums/y164/andysa1966/AFR_Torque.gif

http://i5.photobucket.com/albums/y164/andysa1966/Timing_Torque.gif

http://i5.photobucket.com/albums/y164/andysa1966/Compression_Power.gif

http://i5.photobucket.com/albums/y164/andysa1966/Octane_Requirement.gif

[stigmundfreud]

nice post gelf!

[Bruce Melton]

I think there are different assumptions for PE or WOT. 14.7 there would be a threat to all that you hold dear.

[mr.prick]

isn`t stoich 14.63?

[hquick]

isn`t stoich 14.63?

Yes it is...and that's where the Auto VE tutorial is wrong/misleading also.

[Garry]

Nice info, tnx!

[JezzaB]

isn`t stoich 14.63?

Suppose it depends on how many decimal places you are showing :D

[joecar]

Stoich for gasline is published as being 14.68 which is ~14.7.

[Gelf VXR]

Yes it is...and that's where the Auto VE tutorial is wrong/misleading also.

How is the VE tutorial misleading? Its states 14.63, is this because you don't want to command stoich during AutoVE and you should command 14.7 like I have read in COS threads?

[hquick]

Yep!

[MN C5]

How about adding a feature that would allow us to cut and paste images ect.. into the user notes tab or description tab?

I would like to be able to see certain things associated with the various tables when I'm working on them.

Nice info thanks for taking the time.

[Gelf VXR]

Stoich for gasline is published as being 14.68 which is ~14.7.

I assume EfiLive use 14.63 because thats what the PCM uses in closed loop?


I did a search and 14.63, 14.67 and 14.68 are all there, which is it? I couldn't find a scientific based result..

[joecar]

EFILive uses the value of B3601.

[Gelf VXR]

EFILive uses the value of B3601.

E40 doesn't have that calibration, what I mean is that the PCM programming uses the value 14.63 as stoich?

[joecar]

Oh, it doesn't...? In that case I don't know what is used.

[Xtnct00WS6]

I assume EfiLive use 14.63 because thats what the PCM uses in closed loop?


I did a search and 14.63, 14.67 and 14.68 are all there, which is it? I couldn't find a scientific based result..

Through the research I've done, it seems as though the stoichiometric air-fuel ratio for pure gasoline is 14.7:1. The stoichiometric air-fuel ratio for gasoline with 10% Ethanol is 14.63:1.

Can someone confirm that?!

[swingtan]

In the E38 PCM, stoichiometric fuel ratio is set in B3671 which is a table representing AFR vs Ethanol %. If your car is set up for "Flex Fuel" then this table is used to alter the Stoichiometric figure depending on the amount of ethanol in the fuel. If your car is not set up for "Flex Fuel", then I believe only the 0% Ethanol setting is used which in stock form is set to 14.68:1.

Some figures from the table are as follows.....
Ethanol AFR
00.0% 14.68
06.2% 14.32
12.5% 13.97
18.7% 13.61

and skipping to the end....

100% 9.00 ( which is the correct figure for 100% Ethanol )

Given that the B3671 graph is a straight line between 100% petrol and 100% Ethanol, we can probably assume it's correct.

So the stoichiometric ratio for 10% Ethanol is more like 14.09:1. I run 10% ethanol all the time and my car does not have the "Flex Fuel" option, so it's always using the 0% setting for stoichiometric.

[427]

Thanks heaps-

very helpful-

Nick--

[Chevy366]

Great post , good reference .
Have been playing around with this stuff for a few months (10% Ethanol) I used 14.13 for 10% Ethanol in my LS1 PCM . Does make some difference in performance .
I arrived at 14.13 from a more detailed fuel stoich chart .

[odd boy]

Gents,

I tried toluene as an octane booster. It improved the performance and made the car run faster, even when it is hot!!!!!!!!!!

[Aint Skeered]

Gents,

I tried toluene as an octane booster. It improved the performance and made the car run faster, even when it is hot!!!!!!!!!!

Can you give me a mixxing formula ? I would like to put some in my Nova since its a race car.

[odd boy]

30% octane booster and 70% gas.

Toluene is 114 octane. So use this formula to figure what octane you get:

( Gallons of gas * Octane of gas ) + ( Gallons of octane booster *Octane of booster )
__________________________________________________ _ = new octane
Total Gallons

[The New Pro]

how can I fix the car on 12.6 in full throutal?

[joecar]

how can I fix the car on 12.6 in full throutal?Ok, using the LS1 tables to illustrate...

poor method: you could repeatedly measure with a wideband and adjust the PE table B3618 until you see the WOT AFR you want.

good method: calculate the IFR table and correct the VE and/or MAF tables using a wideband... this then causes the measured AFR to equal the commanded AFR for a greater range of operating points (not just WOT)... and then you set set the PE table B3618 and/or the OL AFR table B3605 for the WOT AFR you want (the AFR selected by the PCM is the richest of all enabled tables at that moment).

In the tunetool, if you type the table id (e.g. B3605) in uppercase into the search box and press Search, you will be taken to that table...

BTW: don't forget to read the scantool and tunetool user manual pdf's... they have lots of useful info on how to operate the tools.

[stigmundfreud]

Joe quick question on IFR, surely the stock ratings should be fairly spot on? Was my (mis)understanding you adjusted IFR if you changed the injectors/fuel system? I know that some tuners just tune on IFR when on a rolling road as one way of acheiving the desired AFR

[ScarabEpic22]

If you are running stock injectors leave IFR alone, IFR/PE raping is a quick way of getting desired AFRs under most conditions but its not tuned properly.

[joecar]

It works better if the IFR table matches the injectors, and you make adjustments elsewhere (MAF and/or VE tables, or in PE table, or in OL table)...

if he doesn't have time to correct the VE and/or MAF, then using a wideband he take a WOT log and adjust the PE table until he gets measured AFR 12.6, even tho his commanded AFR may be different.

[ScarabEpic22]

It works better if the IFR table matches the injectors, and you make adjustments elsewhere (MAF and/or VE tables, or in PE table, or in OL table)...

if he doesn't have time to correct the VE and/or MAF, then using a wideband he take a WOT log and adjust the PE table until he gets measured AFR 12.6, even tho his commanded AFR may be different.

This is what I was trying to say and didnt quite get it across, yes you get the AFR you want even if commanded is leaner/richer. Problem will arise when you get back into CL, LTFTs will be bouncing around trying to command stoich if the VE/MAF tables arent properly setup.

[joecar]

Mike, exactly what Erik said.

[stigmundfreud]

Mike, exactly what Erik said.

what I thought, stock injectors = keep things on the IFR as stock. What is shocking/scary is one of the "most experienced" tuners here tunes stock setups with IFR rates/PE which cannot be good in the long run surely?

If investing in EFILive it surely makes no sense to scrimp on a bit of time. A few hours of consistent logging conditions should get the VE pretty much dialed in, especially on an LS1.

Joe, now running LS3, such a fantastic bit of kit :D

[joecar]

...
If investing in EFILive it surely makes no sense to scrimp on a bit of time. A few hours of consistent logging conditions should get the VE pretty much dialed in, especially on an LS1.We spend lots of time turning physical wrenches/spanners on our cars... we take our time (because we like to see how the guts of it works...:hihi:)...

So why should we not take our time when we turn virtual wrenches/spanners...? :hihi:


Joe, now running LS3, such a fantastic bit of kit :DI bet it's fun to drive...:rockon:

[ScarabEpic22]

LS3 must be a hoot, every time I get out of my LS2 inside a truck I have a fat grin on my face. Ive tricked a few of my buddies into thinking the SS is my old TrailBlazer, then I step on the gas and they sit there with a "Holy Sh|t" look on their face, priceless. :D

Cant wait til I can afford to really put some $$ into my truck for speed...should be fun.

[stigmundfreud]

oh the ls3 is something else, really it is. And yes like you I love getting folks in the car and bimbling along in 3rd doing 30 then just hammer it - the sounds people make :D

[FirstGenThree]

I know this is an older thread but I was reading through some info that linked here. How is it that no one mentioned or discussed that the top 2 charts on the first page contradict each other? Very top chart says 14.0:1 is best mileage (seems unlikely although closer to mean or rich best torque) and the second chart down shows 15.4:1 as best fuel economy. Are either of these correct and if 15.4 is, then is this the target for lean cruise or does it get taken further (17:1?)

[ferocity02]

I know this is an older thread but I was reading through some info that linked here. How is it that no one mentioned or discussed that the top 2 charts on the first page contradict each other? Very top chart says 14.0:1 is best mileage (seems unlikely although closer to mean or rich best torque) and the second chart down shows 15.4:1 as best fuel economy. Are either of these correct and if 15.4 is, then is this the target for lean cruise or does it get taken further (17:1?)

Good question, I noticed that too. The idea of lean cruise is to save fuel by obviously using a lean the mixture not a rich one, so I wonder why the first chart says richer will give best mileage. Maybe richer will give you more power for the same amount of fuel, and thus less fuel required to maintain speed.

[FirstGenThree]

Yes the 14:1 would make better torque = more efficient engine = potential for better mileage. But I thought part of the logic behind lean cruise was not only to consume less fuel but to make less power causing the need for greater throttle position which helps your dynamic compression come closer to your static compression ratio. Throttle defined: to F$%& up an engine.

[sam_pon]

very useful info .
it means that if i need more power , must spend more money

but if i want to have the power only in acceleration , what i can do ?

thanks a lot .

[joecar]

very useful info .
it means that if i need more power , must spend more money

but if i want to have the power only in acceleration , what i can do ?

thanks a lot .With a gasoline engine, to make more power in acceleration you must maximize for torque throughout the operating range...

once torque is maximized then fuel economy is maximized also (engine is now operating at peak efficiency)...

it may take money... but for given hardware (existing or purchased) you will require tuning.


What vehicle do you have...?

[sam_pon]

With a gasoline engine, to make more power in acceleration you must maximize for torque throughout the operating range...

once torque is maximized then fuel economy is maximized also (engine is now operating at peak efficiency)...

it may take money... but for given hardware (existing or purchased) you will require tuning.


What vehicle do you have...?

thanks my dear for your nice reply ,

my car is GMC Envoy 2003 , and my only problem in acceleration , when i try to push the gas pedal for accelerate the car , it accelerate very slowly , and some times without any reason i find it very smoothly , and that always happen when the gas tank almost empty or near quarter full ,

i think there is some problem at gas pump , because when the tank full , the acceleration is very bad , or what you think ?
because i noticed that when the a/c working the acceleration is bad also .
so, i don`t know what is the problem ? is it need a new software for the PCM , and that is very costly here in my country (( Qatar )) .

thanks again for your interest , and have a nice day

[joecar]

thanks my dear for your nice reply ,

my car is GMC Envoy 2003 , and my only problem in acceleration , when i try to push the gas pedal for accelerate the car , it accelerate very slowly , and some times without any reason i find it very smoothly , and that always happen when the gas tank almost empty or near quarter full ,

i think there is some problem at gas pump , because when the tank full , the acceleration is very bad , or what you think ?
because i noticed that when the a/c working the acceleration is bad also .
so, i don`t know what is the problem ? is it need a new software for the PCM , and that is very costly here in my country (( Qatar )) .

thanks again for your interest , and have a nice dayI think you may have a problem with the EVAP system (it may have an air leak), it needs to be diagnosed.

[sam_pon]

I think you may have a problem with the EVAP system (it may have an air leak), it needs to be diagnosed.

dear joecar

i have a OBD2 Cable , could you advice me with a good software to diagnose my car , or this diagnosing must be through the dealer shop ,

thanks in advanced for your help .

[sam_pon]

dear joecar

i have a OBD2 Cable , could you advice me with a good software to diagnose my car , or this diagnosing must be through the dealer shop ,

thanks in advanced for your help .

dear joecar , i am so sorry if my question was stupid question , or i asked it in the wrong place , but as you see i am new for this job ( tuning ) , so if you just lead me to the right way i will appreciate that so much .

thanks in advanced .

[joecar]

Which OBD2 cable do you have...?

Do you have the GM Service Manual for your 2003 GMC Envoy (this is required for diagnosing problems)...?

Have you done mechanical work on your 2003 GMC Envoy (you must be familiar with general procedures/methods/tools)...?

[sam_pon]

this cable :
15523
and i have the service manual for the envoy from 2002 to 2009 in one manual ,
i made many simple things to my car , like changing spark plugs , replace fan clutch , replace brakes pads , cleaning throttle body , changing heating sensor , changing thermostat ... etc

that is all about me , and i am 38 years old , started loving mechanical works from about 20 years .

but i am consider my self a beginner till now .

i am waiting for your reply

thanks a lot

[joecar]

Did it come with software...?

Is it ELM327 compatible...? If it is, Google "ELM327 software".




. . .
i think there is some problem at gas pump , because when the tank full , the acceleration is very bad , or what you think ?
because i noticed that when the a/c working the acceleration is bad also .
. . .




. . .
and i have the service manual for the envoy from 2002 to 2009 in one manual ,
i made many simple things to my car , like changing spark plugs , replace fan clutch , replace brakes pads , cleaning throttle body , changing heating sensor , changing thermostat ... etc

that is all about me , and i am 38 years old , started loving mechanical works from about 20 years .

but i am consider my self a beginner till now .
. . .

Ok, good...

In the GM Service Manual, for your vehicle (2003 GMC Envoy), goto the Engine section, find the Description subsection, read about EVAP (and the other systems)...

then look thru the DTC pages (for your engine) and look closely at the DTC for the EVAP system;

you will have to test your EVAP system for a leak...

if it is leaking air, then it will cause acceleration to be poor (fuel mixture too lean)...

or it may be allowing fuel to be sucked from the tank which will also cause accleration to be poor (fuel mixture too rich).


The GM Service Manual will be your guide, read thru all the various Description and DTC sections to understand how the various systems operate.

Also look at the Engine Control circuit diagrams.

[joecar]

http://en.wikipedia.org/wiki/ELM327
http://scantool.imechatronics.com/downloads.htm
http://www.youtube.com/watch?v=VA-T2qm0lsg
http://www.youtube.com/watch?v=DNUaSp1bRnc

[sam_pon]

thanks my dear for the very useful links , i will try more than one software , to see what is better for diagnosing my problem .

thanks a lot , and have a good day

[joecar]

Also, measure the pressure at the fuel rail, and check if it agrees with the pressure specified by the GM Service Manual.

You have a good day also, let us know how you go.