[IneedAZ]

finally got the gas low enough to add more 93 to drop the percent closer to where i plan to drive the car which will be e30. I over shot it at e25-e28. I am gonna richen it up a little and add a touch of e and see if i get my e30 and make another test hit.

At e25-e28 my Lambda averaging .88 and pulse width ran between 5.5-5.8. Fuel pressure held between 79 and 80psi. I plan to target .87 Lambda at e30 and see how it does.

Anyone know what the high side pressure range should be?

[Joshinator99]

Originally Posted by IneedAZ

finally got the gas low enough to add more 93 to drop the percent closer to where i plan to drive the car which will be e30. I over shot it at e25-e28. I am gonna richen it up a little and add a touch of e and see if i get my e30 and make another test hit.

At e25-e28 my Lambda averaging .88 and pulse width ran between 5.5-5.8. Fuel pressure held between 79 and 80psi. I plan to target .87 Lambda at e30 and see how it does.

Anyone know what the high side pressure range should be?

High pressure will be 2900 psi commanded on a stock fuel system LT4.

[IneedAZ]

Originally Posted by Joshinator99

High pressure will be 2900 psi commanded on a stock fuel system LT4.

ok, thanks...I was between 3600-3800psi.

[JSH]

Adding some ETOH is exactly where I am right now.

[Joshinator99]

Originally Posted by IneedAZ

ok, thanks...I was between 3600-3800psi.

I’ve seen tuners crank up the LT4 HPFP pressure to try to help injector PW go down, but the HPFP moves less volume when you do that… fine line to walk.

[IneedAZ]

Originally Posted by Joshinator99

I’ve seen tuners crank up the LT4 HPFP pressure to try to help injector PW go down, but the HPFP moves less volume when you do that… fine line to walk.

seems i have enough low side and high side but i want to try to get it closer to the e30 and recheck. Not sure the pressures will change much for the small e i need to add to get there. If i can get my .87lambda to match my commanded .87 and keep my PW at 6 or less i will be satisfied with that. I see others running up to 6.5ms on e without issues.

I know the low side pump commanded was raised, but i don't see anything for high side being changed. Any idea what it would be called?

[KingLT1]

How high you can run the injector pulse width depends on how the SOI table is tuned. If you set SOI to inject fuel earlier then you can get away with a wider pulse width. There is a fine line there as well. It's like walking a tight rope with these DI fuel systems.

[IneedAZ]

Originally Posted by KingLT1

How high you can run the injector pulse width depends on how the SOI table is tuned. If you set SOI to inject fuel earlier then you can get away with a wider pulse width. There is a fine line there as well. It's like walking a tight rope with these DI fuel systems.

when i get home from work i will look at the tune and see what was changed for the SOI

the original tuner had me on the rich side at .8Lambda hence my PW was in 6.0-6.2 range on 93 gas. So, if i hit 6pw or better on e30 and my high and low side are holding i think that's pretty good while at .87

I also lowered my KR sensors down quite a bit from what they were at and i still don't see any KR which i am happy about.

[radz28]

Originally Posted by KingLT1

Yes I know. But if you have a flex sensor then you do not use 14.1 across the sliding scale table any longer. The OP is now tuned for E which is why I keep trying to tell him not to worry about E10 AFR anymore. I guess I am not explaining myself very well.

After doing some further research I think what is going on here is that the OP tuner targets leaner based on what his wideband sensor reads because that type of sensor tends to reads leaner then what the actual is. I don't believe his engine is truly running 13.0 on a gas scale.

I appreciate your responses btw! I have read a lot of your posts over at HPT forum!!

I was floored seeing Higgs over here, lol. I never noticed before. Dang near royalty, lol!

Originally Posted by IneedAZ

when i get home from work i will look at the tune and see what was changed for the SOI

the original tuner had me on the rich side at .8Lambda hence my PW was in 6.0-6.2 range on 93 gas. So, if i hit 6pw or better on e30 and my high and low side are holding i think that's pretty good while at .87

I also lowered my KR sensors down quite a bit from what they were at and i still don't see any KR which i am happy about.

If you’re (understandably) concerned it’s too lean, could you just add a little more fuel in PE? It sounds like you already have a plan for a little lower E’, so fattening-up the PE would work, so long as IPW doesn’t get too much into the 6s, no?…

I’m still learning myself :-)

[JANNETTYRACING]

Originally Posted by Higgs Boson

One atmosphere of pressure (sea level) is 14.6959 psi or 100 kpa or 1 bar

Therefore, stoichometric mixture ratio of combustion meaning all parts of gas and air burned is 14.6959 at sea level for ethanol free gasoline

Lambda is used as a common reference across all altitudes and fuel types to represent stoichiometry. .8 lambda is 20% richer than stoich no matter what fuel type and altitude you are at

This means that no matter what is in your tank you can find what percentage richer than stoich works best for your application no matter what the stoich afr value is.

Trying to convert back and forth to understand AFR "comparisons" for E10 at 14.08, E0 at 14.7, or E85 at 9.85 to find your "correct" enrichment ratio is fruitless and will get you confused fast.

Think in terms of percentage of enrichment....10%, 15%, 20%, 25% rather than 13:1, 12.5:1, 12:1, or 11.5:1 because those AFR numbers DO change based on fuel type but the Enrichment Percentage off lambda do not.

Good to see you over here Higgs, NAILED IT

AZ use lambda please and stop with the AFR.

[IneedAZ]

Originally Posted by JANNETTYRACING

AZ use lambda please and stop with the AFR.

i agree and that is what i would prefer...just got complicated cause the dyno at Fasterproms displays in AFR and on top of that i read that it is based on 14.7 Stoich, not the 14.1 our car are based on.

[IneedAZ]

And for those that talked about Inj PW..I asked yet another well known tuner "Kyle" from Goat Rope and he is good with 6 to 6.5, but not higher..Obviously lower is better!! He also said he likes .84 to .87 Lambda on the LT4.

[KingLT1]

Originally Posted by IneedAZ

i agree and that is what i would prefer...just got complicated cause the dyno at Fasterproms displays in AFR and on top of that i read that it is based on 14.7 Stoich, not the 14.1 our car are based on.

Your car uses 14.1 if you put E10 in it. My car uses 14.1 if I put E10 in it. If we use any other fuel, the ECU is no longer based on using 14.1. That is why these cars need a flex sensor and setup correctly. Not all fuel is E10 as it can vary just like E85. Although it usually is only a couple percent variance and the ECU will use fuel trims to clean up any error. If you have a flex sensor with a stoich table setup correctly then the ECU will always be using the correct stoich ratio for the fuel used.

Brett Stewart targets 11.7-12.0 using the 14.7 gas scale on LT4's. He chooses not to use Lambda for whatever reason. I couldn't get a answer why.

Also I would not advise running above 6.0ms on the injectors if the SOI table is stock and not set up to allow more injection time. The start of injection is based around when to start injecting fuel based on crank degrees. We can start injecting fuel earlier then stock which will allow for a little wider pulse widths and still maintain complete combustion. This is why your really good tuners invested in a 5 gas system instead of relying strictly on a wideband the gen5 platform. Once you start spraying fuel outside of the injection window the wideband reading is useless. It will show dead rich and you are likely lean because unburnt fuel is going out the exhaust. I personally seen this happen on my brothers C7Z when it ran out of fuel...it started showing really rich.

[IneedAZ]

Originally Posted by KingLT1

Your car uses 14.1 if you put E10 in it. My car uses 14.1 if I put E10 in it. If we use any other fuel, the ECU is no longer based on using 14.1. That is why these cars need a flex sensor and setup correctly. Not all fuel is E10 as it can vary just like E85. Although it usually is only a couple percent variance and the ECU will use fuel trims to clean up any error. If you have a flex sensor with a stoich table setup correctly then the ECU will always be using the correct stoich ratio for the fuel used.

Brett Stewart targets 11.7-12.0 using the 14.7 gas scale on LT4's. He chooses not to use Lambda for whatever reason. I couldn't get a answer why.

Also I would not advise running above 6.0ms on the injectors if the SOI table is stock and not set up to allow more injection time. The start of injection is based around when to start injecting fuel based on crank degrees. We can start injecting fuel earlier then stock which will allow for a little wider pulse widths and still maintain complete combustion. This is why your really good tuners invested in a 5 gas system instead of relying strictly on a wideband the gen5 platform. Once you start spraying fuel outside of the injection window the wideband reading is useless. It will show dead rich and you are likely lean because unburnt fuel is going out the exhaust. I personally seen this happen on my brothers C7Z when it ran out of fuel...it started showing really rich.

Be nice if the gauge and software companies went to Lambda only which will force everyone to speak the same language...The 1st day of tuning i asked my tuner what Lambda he likes and he said he likes AFR...Just makes it more difficult for us novices. As far as the SOI tables..i know mine were adjusted, but since i am not familiar with them i dont know to what extent.

I tried to do a log last night, but with our temps still near 90 my DR heat up quickly and cant get a WOT more than second or two without having to back off. I started at 26Cold, but the time i got to the street to test it i was 28/29 psi. I put it at 26 thinking with cooler weather i will drop to 24ish cold. Might be another month before i see the cooler weather that will drop them. Guess for now i will drop them myself.