taking away some fuel around 3500rpm and up

[ZL1Killa]

Ok, well i just bought efi live and i have had it for around a week and I'm wondering how to simply take away some fuel above 4500rpm.


My air to fuel is 13.3:1 throughout the board till around 44-4500rpm and on up, which it is at 12.1:1 then, rich. I have heard about copying high spark table to low spark table and do this and that and then you are in SD mode...i have printed all that paper out and I will be trying that next.

[Tordne]

I guess the first question to ask is: The AFR's that you are seeing/quoting, are they commanded, or do you have a Wide Band 02 it measure actual AFR's?

Depending on how aggressively you are accelerating (i.e. WOT) the commanded AFR's will be determined from the PE (Power Enrichment) tables.

Some of the stock tunes do actually command AFR's as low as 11.9 (2004 Corvette Z06 for example). So what you are seeing could be expected.

Cheers,
Andrew

[GMPX]

Ok, well i just bought efi live and i have had it for around a week and I'm wondering how to simply take away some fuel above 4500rpm.


My air to fuel is 13.3:1 throughout the board till around 44-4500rpm and on up, which it is at 12.1:1 then, rich. I have heard about copying high spark table to low spark table and do this and that and then you are in SD mode...i have printed all that paper out and I will be trying that next.

Yeah, commanded AFR or measured?.
13.3 is too lean, 12.1 is fine, really!!.
When it goes really rich it might be cat converter protection kicking in, either raise the temp thresholds or turn it off.

Cheers,
Ross

[Scoota]

Yeah, commanded AFR or measured?.
13.3 is too lean, 12.1 is fine, really!!.
When it goes really rich it might be cat converter protection kicking in, either raise the temp thresholds or turn it off.

Cheers,
Ross
Just one thing on the subject of Air fuel Ratios, Yes I tune my cars by AFR's, but I also back them up with checking the Lamda results. My best results have been when the Lamda is 0.9 across the board, 0.9 Lamda is where you will achieve the absolute torque that your engine will produce as far as fuel goes. Now that’s easy for me to say as I log Lamda on the dyno. When you compare the Lamda in relation to the AFR's, the AFR's aren't where you thought you should have set them to, they may start at 12.4:1 and raise to around the 13.0:1 through the mid to hi rpm range and then drop to around 12.4:1. "That's not a problem".
The Lamda results always play a Huge part in the art of tuning for me.
Having said that, I thought I search for a Pid that would log Lamda. Not that I need a Pid to log Lamda but others may like to try logging it. I couldn’t find any Pid’s. I may not be looking hard enough, if there isn’t a Pid available, could one possibly be added.
It was just a thought guys.

Cheers Scotty.

[dfe1]

Please explain the lambda back-up. As far as I know, lambda is simply another unit of measurement for air/fuel ratio. A lambda of 1 equates to an air/fuel ratio of 14.7:1 and lambda values above and below 1 are essentially factors that can be applied to 14.7:1 to convert lambda to actual air/fuel ratio. A lambda of .9 equates to an air/fuel ratio of 13.23:1 (14.7*.9=13.23). So anytime you have a lambda of .9, you should have an AFR of 13.23, and anytime you don't have an AFR of 13.23, you shouldn't have a lambda of .9.

[Scoota]

Please explain the lambda back-up. As far as I know, lambda is simply another unit of measurement for air/fuel ratio. A lambda of 1 equates to an air/fuel ratio of 14.7:1 and lambda values above and below 1 are essentially factors that can be applied to 14.7:1 to convert lambda to actual air/fuel ratio. A lambda of .9 equates to an air/fuel ratio of 13.23:1 (14.7*.9=13.23). So anytime you have a lambda of .9, you should have an AFR of 13.23, and anytime you don't have an AFR of 13.23, you shouldn't have a lambda of .9.
You’ve made a good point. It was more of a reference to lambda than anything without having to do the math.
Having read what I had wrote, I probably wouldn’t have worded it that way the second time around.
One of the points that I was trying to make was that the most amount of torque was to be gained at around and no higher than 0.9 lambda which is as you say 13.23:1 I graph lambda on the Dyno and AFR's on the laptop. Going by the math, my calibration is out by 0.4:1.
Sorry for the confusion.
Cheers Scotty.

[dfe1]

No problem, I was just wondering if the math worked the same in Australia as it does in the US. Seriously, each tuner develops his/her own way of doing things and I've found that sometimes it's a matter of personal preference and other times there are advantages to doing things a certain way. I just wanted to make sure I wasn't missing something. Thanks for the reply. Also, in reference to the original question, I've found that many LS1/LS6 air/fuel calibrations go really ruch around 4500 rpm because of converter overtemp protection. Unless you disable converter over-temp, you'll play hell trying to get air/fuel ratios above 11.9-12.1 range-- both commanded and actual. In fact, if you look at the dyno curves for some vehicles with stock tunes, you can see precisely where over-temp fuel kicks in because the power curve has a negative blip when the extra fuel kicks in.

[ZL1Killa]

the air to fuel that we were looking at was measured by a wideband that stuck way up in the tailpipe.

Sorry but i will have to modify this a little..it goes rich above 3500rpm.

The car was placed on a dynojet dyno in Benson at Fastlane Motorsports and Caleb dynoed the car. Of course you set the car at a certain rpm and then hit log and go WOT. In the beginning the car was running at around 13.x : 1 ratio (low 13.x's) then it went up to 13.6 and then 13.1 and then went on down to 12.1:1 above about 3500.

What is LAMBDA?? if you can't tell I'm new to all of this
about the catalytic converter protection ...is that under cat converter in efi live? under parameters and I need to disable that whole thing right?

[Tordne]

To disable Cat Converter protection set {B0701} to Disabled.

Also have a look at {B3618}. This table will show you what will be commanded when at WOT vs. RPM.

Good luck.

[ZL1Killa]

To disable Cat Converter protection set {B0701} to Disabled.

Also have a look at {B3618}. This table will show you what will be commanded when at WOT vs. RPM.

Good luck.

the B3618 is what we have changed and know that it affects the AFR, we know about that table...thanks man.

If you disable the cat converter protection, can't you lean out too much or richen the car too much and then cause issues?? that cat protection is there for why?? the temps of the cat protection are on mine at :

Cat converter low protection temp 830 (degrees C)
medium 840
high 850
extreme 920

830 is 1,526 in F..don't you want your Exhaust gas temps to be less than a certain temp..if you disable the cat protect then EGT could vary a lot and risk damage if you change some things too far right??

[GMPX]

Having logged EGT's on my car just before the cat, it takes about 8 - 10 seconds of WOT to reach the sort of temps GM like to kick the cat protection fueling in. Remember, it is a calculated value, not like some Euro cars that do run EGT sensors to protect the cats on the unlimited speed highways.

You really need to turn it off or you will end up getting inconsistant AFR's.
Eg, if in P.E mode and you are commanding 12.5:1, all things equal, you will get 12.5:1 at all RPM's, you will find with cat protection that will drop to about 11.0 - 11.5:1 by the end of the run. You don't risk going too lean with cat protection off unless something else is wrong (MAF Table, VE etc).

Some people like to raise the temps to much higher values too instead of turning it off, I suspect it was in there to help reduce warranty claims.

Cheers,
Ross

[dfe1]

You have to keep in mind that original equipment calibrations have to contain a fairly large "idiot factor". I'm sure you,ve heard cars driving along sounding like there's a diesel under the hood and the driver never lifts his/her foot off the gas pedal. Then when he/she puts a hole in a piston, cracks a ring or burns a valve, he/she determines that it's a result of a manufacturing defect. Since GM has to cover idiot drivers for 3 years or 36,000 miles there are a number of safeguards built into stock calibrations. If you're doing your own tuning, hopefully, you don't need these safeguards because you'll be aware of problems that crop up and take appropriate action. I've turned converter overtemp off in a number of vehicles and never had a problem. I'd advise you to disable cat overtemp as mentioned, then log air/fuel with a wideband and tune from there.

[Dirk Diggler]

Hell mine was turned off when I still had cats on the car

[ZL1Killa]

we have created a table based for the PE based on RPM and we have created that table to give us the commanded Air to fuel at WOT. I can attach this excel sheet later if needed and basically we took the stoich reference, basically 14.7 or whatever you want to use 14.6 and divided it by 0.9 all the way up to 1.26 which 1.26 yeilds an air to fuel of 11.67. thats what we are using to calculate what to put into the pe based on RPM table. Hypertech programming put in values starting at 1.1 and went on up to 1.15 at the highest value. Hypertech did lean me out some and did give me power, so they do advertise correctly I can share that tune if anyone would like to see the hypertech tune. I have my stock tune, hypertech's tune, and the tune we are running now, just let me know. The only thing that is modified for performance wise, is simplet he PE based on RPM values and the spark tables.

1.15=12.78 so that cat protection has to be causing us to go rich. Thank yall for the help on that, i will turn that off here soon.

if anyone would like the excell sheet let me know, and with that excel sheet i have included a tool thanks to RedHardSupra (marcinpohl@gmail.com) he found it and modified it , he doesn't know the original creator, but whoever it was thanks!!!!

[ZL1Killa]

i raised the temps on the cat protection except for the extreme temp.

so now my temps read 860 870 880 and extreme 920 these are in Celsius.

I think we might change the PE based on rpm to add a little fuel and i will turn the cat protect off.

Preciate the help yall. I just had my wisdom teeth cut out today!!!! what fun!! sleep is a good thing :)

[ZL1Killa]

ok now i got that down pat and I have turned off the cat converter protection and leaned out my car some (to a safe degree)

now what is it that i hear about the VE table (main ve table)

you either add or subtract values from this table and it does something i know that much....

I had not and do no plan on doing an SD tune. I want to keep the MAF intact and running with the car (if thats best-this is a daily driver). I also want to add that i do have a modified MAF --descreened, what under the MAF do i need to change....should i raise any values in B5001 table?? the car does run fine.