How do I add fuel?

[Blk02Ls1A4]

My ltft's are adding 5-7% fuel in part throttle operation. I know I need to get these 0 or slightly negative to get the ltft's 0 at WOT. Where can I go to add the fuel? I was looking to add it to the main ve table, but after doing some reading on ls1tuning.com and ls1tech.com it seems like that might not work out too well. Please help this tuning newbie.

ps: Flashscan rocks! I cant get over how awesome it is.

[Drake]

Well, there are several ways and places to work out the LTFTs. I'm a begineer like you, so please keep that in mind...

My 2002 F-body was running too lean. The LTFTs were running in the +5 to +6 ranges, pretty much across the whole range. Here are the three things I know you can change to get them down to toward zero, or slightly negative:

VE table
IFR table
MAF table

I've been reading and experimenting with all three. The best way I have found to get results across the board is with the MAF table. I managed to get everything above 10inHG-MAP to be in the -1 to -2 ranges with the MAF table. Unfortunately, everything below 10inHG-MAP is now running in the -6 to -8 ranges... I'm now trying to use the VE table to bring down those areas. I'm really not sure if this is the correct approach, but it seems to be working. Maybe someone else (who knows what they are doing) can chime in.

[jfpilla]

Those are the main tables that are used to set trims. You will notice that almost anything you change in any airflow, fuel and even timing table will affect trims.
Suggest you list your mods so that suggestions can be better targeted. ex.If you changed your air intake you might go to the MAF. Change injectors and go to IFR. Change everthing and the fun begins.
You should use MAP kPa. Most tables use it and is the standard for understanding each other.

[87gmc]

Same problem here what should I do?

99 GMC 5.3L All stock except for k&N filter. Where do I start to get them down to 0%

Gotta love the way efilive exports it into excel :-)


Cell# MAP/RPM boundaries Bank-1 Bank-2
0 MAP 0.00..33.0 kPa/RPM 0..900 0.00% 1.56%
1 MAP 0.00..33.0 kPa/RPM 900..1400 0.00% 1.56%
2 MAP 0.00..33.0 kPa/RPM 1400..2200 11.72% 12.30%
3 MAP 0.00..33.0 kPa/RPM 2200+ 11.72% 12.30%
4 MAP 33.0..55.0 kPa/RPM 0..900 1.95% 4.49%
5 MAP 33.0..55.0 kPa/RPM 900..1400 4.88% 6.45%
6 MAP 33.0..55.0 kPa/RPM 1400..2200 9.77% 9.37%
7 MAP 33.0..55.0 kPa/RPM 2200+ 11.72% 12.30%
8 MAP 55.0..77.0 kPa/RPM 0..900 11.72% 12.30%
9 MAP 55.0..77.0 kPa/RPM 900..1400 7.81% 8.40%
10 MAP 55.0..77.0 kPa/RPM 1400..2200 8.79% 9.37%
11 MAP 55.0..77.0 kPa/RPM 2200+ 11.72% 12.30%
12 MAP 77.0+ kPa/RPM 0..900 11.72% 12.30%
13 MAP 77.0+ kPa/RPM 900..1400 11.72% 12.30%
14 MAP 77.0+ kPa/RPM 1400..2200 11.72% 12.30%
15 MAP 77.0+ kPa/RPM 2200+ 11.72% 12.30%
16 P/N: A/C On 11.72% 12.30%
17 P/N: A/C Off 11.72% 12.30%
18 In gear: A/C On 11.72% 12.30%
19 In gear: A/C Off 4.88% 5.47%
20 Cold idle 5.86% 6.45%
21 Deceleration 10.74% 11.72%
22 WOT 10.74% 14.65%

[jfpilla]

Same problem here what should I do?

99 GMC 5.3L All stock except for k&N filter. Where do I start to get them down to 0%

Gotta love the way efilive exports it into excel :-)


Cell# MAP/RPM boundaries Bank-1 Bank-2
0 MAP 0.00..33.0 kPa/RPM 0..900 0.00% 1.56%
1 MAP 0.00..33.0 kPa/RPM 900..1400 0.00% 1.56%
2 MAP 0.00..33.0 kPa/RPM 1400..2200 11.72% 12.30%
3 MAP 0.00..33.0 kPa/RPM 2200+ 11.72% 12.30%
4 MAP 33.0..55.0 kPa/RPM 0..900 1.95% 4.49%
5 MAP 33.0..55.0 kPa/RPM 900..1400 4.88% 6.45%
6 MAP 33.0..55.0 kPa/RPM 1400..2200 9.77% 9.37%
7 MAP 33.0..55.0 kPa/RPM 2200+ 11.72% 12.30%
8 MAP 55.0..77.0 kPa/RPM 0..900 11.72% 12.30%
9 MAP 55.0..77.0 kPa/RPM 900..1400 7.81% 8.40%
10 MAP 55.0..77.0 kPa/RPM 1400..2200 8.79% 9.37%
11 MAP 55.0..77.0 kPa/RPM 2200+ 11.72% 12.30%
12 MAP 77.0+ kPa/RPM 0..900 11.72% 12.30%
13 MAP 77.0+ kPa/RPM 900..1400 11.72% 12.30%
14 MAP 77.0+ kPa/RPM 1400..2200 11.72% 12.30%
15 MAP 77.0+ kPa/RPM 2200+ 11.72% 12.30%
16 P/N: A/C On 11.72% 12.30%
17 P/N: A/C Off 11.72% 12.30%
18 In gear: A/C On 11.72% 12.30%
19 In gear: A/C Off 4.88% 5.47%
20 Cold idle 5.86% 6.45%
21 Deceleration 10.74% 11.72%
22 WOT 10.74% 14.65%

I think the 99' MAF has an impact on the 4l60. If so, reduce the Injector Flow Rate by 10% and see the result.

[Blk02Ls1A4]

hmmm, so if I reduce my injector flow rate based on map then that will make the ltft's go negative? Interesting... Now if a 2002 ls1 has 28.6 # injectors then why are mine flowing from 28.7 to 31.4, as map pressure increases?

As for mods, lid, headers, cats, catback, S2, SLP rocker arms.

So I would want to reduce my IFR by 7% across the board, so multiply the whole thing by -7% ?

[87gmc]

Same problem here what should I do?

99 GMC 5.3L All stock except for k&N filter. Where do I start to get them down to 0%

Gotta love the way efilive exports it into excel :-)


Cell# MAP/RPM boundaries Bank-1 Bank-2
0 MAP 0.00..33.0 kPa/RPM 0..900 0.00% 1.56%
1 MAP 0.00..33.0 kPa/RPM 900..1400 0.00% 1.56%
2 MAP 0.00..33.0 kPa/RPM 1400..2200 11.72% 12.30%
3 MAP 0.00..33.0 kPa/RPM 2200+ 11.72% 12.30%
4 MAP 33.0..55.0 kPa/RPM 0..900 1.95% 4.49%
5 MAP 33.0..55.0 kPa/RPM 900..1400 4.88% 6.45%
6 MAP 33.0..55.0 kPa/RPM 1400..2200 9.77% 9.37%
7 MAP 33.0..55.0 kPa/RPM 2200+ 11.72% 12.30%
8 MAP 55.0..77.0 kPa/RPM 0..900 11.72% 12.30%
9 MAP 55.0..77.0 kPa/RPM 900..1400 7.81% 8.40%
10 MAP 55.0..77.0 kPa/RPM 1400..2200 8.79% 9.37%
11 MAP 55.0..77.0 kPa/RPM 2200+ 11.72% 12.30%
12 MAP 77.0+ kPa/RPM 0..900 11.72% 12.30%
13 MAP 77.0+ kPa/RPM 900..1400 11.72% 12.30%
14 MAP 77.0+ kPa/RPM 1400..2200 11.72% 12.30%
15 MAP 77.0+ kPa/RPM 2200+ 11.72% 12.30%
16 P/N: A/C On 11.72% 12.30%
17 P/N: A/C Off 11.72% 12.30%
18 In gear: A/C On 11.72% 12.30%
19 In gear: A/C Off 4.88% 5.47%
20 Cold idle 5.86% 6.45%
21 Deceleration 10.74% 11.72%
22 WOT 10.74% 14.65%

I think the 99' MAF has an impact on the 4l60. If so, reduce the Injector Flow Rate by 10% and see the result. Can you explain how the maf impacts the trans. What does it effect or...........

[Blk02Ls1A4]

the Maf is used to calculate the ammount of air entering the engine.
The ammount of air that enters the engine is used to calculate the engine's torque output.
Shift speed, line pressure, and torque reduction are all adjusted based on the engine's calculated torque output.

[jfpilla]

hmmm, so if I reduce my injector flow rate based on map then that will make the ltft's go negative?

>>>Yes, your telling the PCM that you have smaller injectors than what you have. The PW is increased to add fuel and the adjustment to add air causes less Pos. trims.

Interesting... Now if a 2002 ls1 has 28.6 # injectors then why are mine flowing from 28.7 to 31.4, as map pressure increases?

>>> Don't know. Why do you ask?

As for mods, lid, headers, cats, catback, S2, SLP rocker arms.

So I would want to reduce my IFR by 7% across the board, so multiply the whole thing by -7%

>>> -7% or any # to determine what changes result in what levels for your car.

[XLR8NSS]

hmmm, so if I reduce my injector flow rate based on map then that will make the ltft's go negative? Interesting... Now if a 2002 ls1 has 28.6 # injectors then why are mine flowing from 28.7 to 31.4, as map pressure increases?

As for mods, lid, headers, cats, catback, S2, SLP rocker arms.

So I would want to reduce my IFR by 7% across the board, so multiply the whole thing by -7% ?

The pressure is increasing in the intake manifold but, the fuel pressure is not manifold referenced so the flow of the injector has to be increased to "fight" the extra pressure in the manifold as the MAP rises.

On '99-'03 GM trucks the fuel pressure is manifold referenced meaning it rises as the MAP rises. The values for IFR vs. MAP are constant in a system like this.

[87gmc]

So where on flashscan can you adjust the fuel pump pressure?

[XLR8NSS]

So where on flashscan can you adjust the fuel pump pressure?

I don't have my Flashscan setup yet but, I don't think that is even possible through the PCM.

The Injector Flow rate is increased as MAP increases not the fuel pressure.

On the trucks the fuel pressure is increased mechanically with the manifold referenced fuel pressure regulator as the MAP increases. Since the fuel pressure is increased with MAP the IFR stays the same at all MAP values.

Just two different ways to get the same end result. :)

[Blk02Ls1A4]

if the engine needs more fuel and the ltft's are adding fuel, then how does decreacing injector flow rates help?

[87gmc]

I was also thinking someone said my transmission depends on my maf. Is it possible that the maf is dirty from oil off the k&n? Transmission is taking it sweet time shifting from 1-2 on WOT its also losing timing in this area.

[XLR8NSS]

if the engine needs more fuel and the ltft's are adding fuel, then how does decreacing injector flow rates help?

The Injector Flow Rate tells the computer how big the injector is. If you decrease the IFR the computer thinks the injectors are smaller and will keep the injector on longer. Now you have the same size injector still but, the computer is keeping it on longer which means more fuel is being delivered. :)

[Drake]

So where on flashscan can you adjust the fuel pump pressure?

Interesting... do trucks and other non F-body and Y-body vehicles use something other than demand type fuel systems?

[XLR8NSS]

So where on flashscan can you adjust the fuel pump pressure?

Interesting... do trucks and other non F-body and Y-body vehicles use something other than demand type fuel systems?

It might be a possiblity. I was just looking around in a LS1Edit(gasp) file and saw this table. I don't know if it's actually active on my truck or Fbody but, the numbers are all 1 so it wouldn't do anything anyway if it was. Someone adjust it and see if anything happens. ;) The scale is from 4.5 volts to 18 but, the lower end is cutoff in the picture.

[Drake]

Weird... I've never heard of or seen a fuel pressure sensor returning information to anything. Not sure how that would work.

Ls1ed...what? :wink:

[XLR8NSS]

Yeah, I assume it's for some other platform. Like you say I've never seen any pressure sensor.

As much as we might not like to mention it sometimes Edit was one of the first on the block. We all probably have old Edit cables in our closet. :P ;)

[GMPX]

It might be a possiblity. I was just looking around in a LS1Edit(gasp) file and saw this table.

One more outburst like that and you'll get banned :wink: :wink:

Table does nothing more than adjust Injector pulse width based on battery voltage, it compensates for the fact the pump would be running slower and injector opening times for a lower/higher voltage.

Cheers,
Ross

[87gmc]

Adjusted my IFR and lowered ltft's from +8-10% to -1%. Some of the lower areas were -6--10% Adjusted VE in that area and solved my problem. AFter all these adjustments you could feel the difference as far as normal driving speeds. Felt like you didnt have to smash on the pedal as much to get it going. Maybe its a mental thing but it feels all better to me.

[jfpilla]

Adjusted my IFR and lowered ltft's from +8-10% to -1%. Some of the lower areas were -6--10% Adjusted VE in that area and solved my problem. AFter all these adjustments you could feel the difference as far as normal driving speeds. Felt like you did have to smash on the pedal as much to get it going. Maybe its a mental thing but it feels all better to me.

Nice job.
We're all mental, are we not? :shock:

[XLR8NSS]

It might be a possiblity. I was just looking around in a LS1Edit(gasp) file and saw this table.

One more outburst like that and you'll get banned :wink: :wink:

Table does nothing more than adjust Injector pulse width based on battery voltage, it compensates for the fact the pump would be running slower and injector opening times for a lower/higher voltage.

Cheers,
Ross

I promise no more outburst once my EFILive cable gets sent after the new production run. 8) ;)

That is nice info to know about that table. Not a particularly useful table is it.

[Drake]

Not useful unless you're having to limp home when your power system goes (partially) belly up.

[Delco]

Adjusted my IFR and lowered ltft's from +8-10% to -1%. Some of the lower areas were -6--10% Adjusted VE in that area and solved my problem. AFter all these adjustments you could feel the difference as far as normal driving speeds. Felt like you did have to smash on the pedal as much to get it going. Maybe its a mental thing but it feels all better to me.

Nice job.
We're all mental, are we not? :shock:

Like all the tables in the PCM they have a use when needed , in your case its tuned out because the calibration engineer attacked the problem from a different angle.

[jfpilla]

Adjusted my IFR and lowered ltft's from +8-10% to -1%. Some of the lower areas were -6--10% Adjusted VE in that area and solved my problem. AFter all these adjustments you could feel the difference as far as normal driving speeds. Felt like you did have to smash on the pedal as much to get it going. Maybe its a mental thing but it feels all better to me.

Nice job.
We're all mental, are we not? :shock:

Like all the tables in the PCM they have a use when needed , in your case its tuned out because the calibration engineer attacked the problem from a different angle.

What am I missing?????????

[Delco]

Adjusted my IFR and lowered ltft's from +8-10% to -1%. Some of the lower areas were -6--10% Adjusted VE in that area and solved my problem. AFter all these adjustments you could feel the difference as far as normal driving speeds. Felt like you did have to smash on the pedal as much to get it going. Maybe its a mental thing but it feels all better to me.

Nice job.
We're all mental, are we not? :shock:

Like all the tables in the PCM they have a use when needed , in your case its tuned out because the calibration engineer attacked the problem from a different angle.

What am I missing?????????

Nothing , the calibration engineers have a lat of tables added as they are developing a calibration and on different platforms , sometimes they are not used but there for only one particular cal or they added it then decided to do it with a different table ie the intake temp spark table and the intake temp spark scaler both have the same function and in most cases only one of the two tables are used

[dfe1]

When you're trying to understand the application of various tables, keep in mind that recent pcm architecture is typically designed for use with a variety of engine/chassis combinations. The same pcm hardware/software scheme is found in Corvettes, F-bodies, GTOs, trucks and SUVs. Consequently, tables that may figure prominently in one application may not even be used in another. Also, it's best to leave the MAF table unaltered unless you've changed MAF sensors or have a specific MAF-related problem. LS1/LS6 calibrations rely on MAF readings (grams/cyl) for a variety of functions. If you alter the MAF tables to address a fuel issue, you may inadvertantly alter spark timing (which is referenced to air flow and engine speed). You should be able to get your fuel trims in line without changing the MAF tables.

[DebianDog]

I was also thinking someone said my transmission depends on my maf. Is it possible that the maf is dirty from oil off the k&n? Transmission is taking it sweet time shifting from 1-2 on WOT its also losing timing in this area.

A dirty MAF will mess with the tranny. Brake cleaner or Alcohol and a Q-Tip will fix that!