Injector Advice Needed - Runs Lean (Not Stock!)

[gamefreakgc]

Anyone with tuning/custom build experience, your advice would be appreciated!

I have a Supercharged 5VZ-FE engine with larger intake, swapped the MAF for the less restrictive 99-02 MAF, Deckplate mod, headers, and other things to help air flow in and out much quicker. Let's just say I've succeeded and now I've got a problem.

My engine runs lean. Not under boost, I have a methanol injection system that takes care of that. I'm talking about driving around town or inching along in traffic. My long-term fuel trims go between 16.5 - 19.5. At idle, it's pegged at 19.5, which is the maximum value. Which means, if I understand this right, my injectors flow is increased by 16.5%-19.5%. A value of 20% or more will throw a check engine light. The short-term trims stay near 0% for the most part, which is good. Last part, when I had the headers installed it ran a little funny (turns out it was running lean, but I didn't know that yet) so I went ahead and pulled the EFI fuse to reset the fuel trims to stock. Bad idea! My AFR at idle, 10 MPH, 30 MPH, etc. was pegged at 17+ AFR. A few times it went unreadable, over 18 AFR. Finally after about 10 minutes of driving the computer kicked in and went back to 14.7 but scared the heck out of me for a while.

So, that leads me to my question, do I need larger injectors?

Our stock injectors flow at ~240cc. If my math is any good, just for stock driving around town I would need injectors between 240 * 1.16 (278.4 cc) and 240 * 1.19 (285.6 cc). I'd probably push that a little higher, since I need more fuel anyway with the S/C system. Does this sound right? I'd appreciate thoughts.

P.S. I am buying a piggyback controller very soon.

This is the stock injector we have, measured by WitchHunter Performance (an injector servicing company):

 

[JayRolla]

Anyone with tuning/custom build experience, your advice would be appreciated!

I have a Supercharged 5VZ-FE engine with larger intake, swapped the MAF for the less restrictive 99-02 MAF, Deckplate mod, headers, and other things to help air flow in and out much quicker. Let's just say I've succeeded and now I've got a problem.

My engine runs lean. Not under boost, I have a methanol injection system that takes care of that. I'm talking about driving around town or inching along in traffic. My long-term fuel trims go between 16.5 - 19.5. At idle, it's pegged at 19.5, which is the maximum value. Which means, if I understand this right, my injectors flow is increased by 16.5%-19.5%. A value of 20% or more will throw a check engine light. The short-term trims stay near 0% for the most part, which is good. Last part, when I had the headers installed it ran a little funny (turns out it was running lean, but I didn't know that yet) so I went ahead and pulled the EFI fuse to reset the fuel trims to stock. Bad idea! My AFR at idle, 10 MPH, 30 MPH, etc. was pegged at 17+ AFR. A few times it went unreadable, over 18 AFR. Finally after about 10 minutes of driving the computer kicked in and went back to 14.7 but scared the heck out of me for a while.

So, that leads me to my question, do I need larger injectors?

Our stock injectors flow at ~240cc. If my math is any good, just for stock driving around town I would need injectors between 240 * 1.16 (278.4 cc) and 240 * 1.19 (285.6 cc). I'd probably push that a little higher, since I need more fuel anyway with the S/C system. Does this sound right? I'd appreciate thoughts.

P.S. I am buying a piggyback controller very soon.

This is the stock injector we have, measured by WitchHunter Performance (an injector servicing company):

The LTFT is interpreted over time off the STFT. So if your maxed on the long term the short term has been running lean.

Usually when swapping the maf it changes the tune due to more flow. If you do not have a piggy back to compensate for this then you have been running lean in closed loop. Dont be worried because without much load you can run really lean without issues.

You most likely just need to get it tuned. You do not need more fuel at idle and cruise and your meth injection compensates for more fuel at WOT. You get the piggy back and tune closed loop you should be fine.

 

[19963.4lsr5]

The LTFT is the representation of the STFT maxing out in the + or - direction. Every time the STFT maxes out at -30 or +30 it will add or subtract a 1 to the LTFT and zero the STFT and start over. Think of the LTFT as the left of the decimal point and the STFT as the right of the decimal point. Like this LTFT.STFT.

Ever look at your fuel pressure at the fuel rail?


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[gamefreakgc]

The LTFT is interpreted over time off the STFT. So if your maxed on the long term the short term has been running lean.

Usually when swapping the maf it changes the tune due to more flow. If you do not have a piggy back to compensate for this then you have been running lean in closed loop. Dont be worried because without much load you can run really lean without issues.

You most likely just need to get it tuned. You do not need more fuel at idle and cruise and your meth injection compensates for more fuel at WOT. You get the piggy back and tune closed loop you should be fine.

When I do get it tuned though, will my injectors max out pretty quick? I don't necessarily want to go to pay to get a tune, and find out my injectors are running at 100% duty cycle or something. I though that a near 0 value for LTFT is ideal?

What I might do, is put the stock MAF back in and see if it really is running lean or not.

 

[JayRolla]

When I do get it tuned though, will my injectors max out pretty quick? I don't necessarily want to go to pay to get a tune, and find out my injectors are running at 100% duty cycle or something. I though that a near 0 value for LTFT is ideal?

What I might do, is put the stock MAF back in and see if it really is running lean or not.

Near 0 is ideal. But it wont get to 0 until you tune the difference in your maf. Im sure it would run just fine if you installed your old maf.

I believe the odb2 scanners will read IDC. What is your IDC at full throttle and high rpm?

The stock injectors should beable to handle closed loop cruising no problem. The meth injection acts as fuel and dramatically lowers IDC's at wide open throttle. But like you said the best option would be larger injectors so when you do get it tuned you dont run out of fuel.

I would also recommend a denso Lancer evo 8/9 190lph fuel pump. This way you dont run out of fuel at all. The walbros fail and are super loud.

 

[gamefreakgc]

Near 0 is ideal. But it wont get to 0 until you tune the difference in your maf. Im sure it would run just fine if you installed your old maf.

I believe the odb2 scanners will read IDC. What is your IDC at full throttle and high rpm?

The stock injectors should beable to handle closed loop cruising no problem. The meth injection acts as fuel and dramatically lowers IDC's at wide open throttle. But like you said the best option would be larger injectors so when you do get it tuned you dont run out of fuel.

I would also recommend a denso Lancer evo 8/9 190lph fuel pump. This way you dont run out of fuel at all. The walbros fail and are super loud.

I will get back to you on IDC soon, I'm not sure if my scanner does read it or not.

The thing is, pre-header with the stock MAF I was already at +7 to +9 constant on LTFT. I need to swap the stock MAF back in, but I'm thinking my current readings are actually somewhat accurate.

Would putting in larger injectors be pointless to do without a larger fuel pump?

 

[JayRolla]

I will get back to you on IDC soon, I'm not sure if my scanner does read it or not.

The thing is, pre-header with the stock MAF I was already at +7 to +9 constant on LTFT. I need to swap the stock MAF back in, but I'm thinking my current readings are actually somewhat accurate.

Would putting in larger injectors be pointless to do without a larger fuel pump?

It might be pointless if the pump runs out. The 7th injector kit comes with a 190lph fuel pump so I'm sure with the 2.1 pulley, larger injectors that you do need an upgraded fuel pump.

 

[gamefreakgc]

Near 0 is ideal. But it wont get to 0 until you tune the difference in your maf. Im sure it would run just fine if you installed your old maf.

I believe the odb2 scanners will read IDC. What is your IDC at full throttle and high rpm?

The stock injectors should beable to handle closed loop cruising no problem. The meth injection acts as fuel and dramatically lowers IDC's at wide open throttle. But like you said the best option would be larger injectors so when you do get it tuned you dont run out of fuel.

I would also recommend a denso Lancer evo 8/9 190lph fuel pump. This way you dont run out of fuel at all. The walbros fail and are super loud.

No go on IDC, or anything else fuel related really besides LTFT & STFT.

I'm going to slap my old MAF & airbox on this evening and take it for a spin and see how the readings are post-header. That will decide if the MAF swap is the reason behind being pegged at 19.5.

 

[JayRolla]

No go on IDC, or anything else fuel related really besides LTFT & STFT.

I'm going to slap my old MAF & airbox on this evening and take it for a spin and see how the readings are post-header. That will rule out the MAF swap as the reason behind being pegged at 19.5.

Just remember to watch STFT over the entire drive during cruise to see how much fuel is being added or removed. Usually I would datalog this data and look at it afterwards. For the LTFT to adjust it may take quite a few miles of driving.

 

[gamefreakgc]

Just remember to watch STFT over the entire drive during cruise to see how much fuel is being added or removed. Usually I would datalog this data and look at it afterwards. For the LTFT to adjust it may take quite a few miles of driving.

From what I remember the last time I did it, it took about 5ish miles for the LTFT to kick in. Was stuck at 0, and then bam 19.5 and has never really moved since.

I realize I'm in uncharted territory with the MAF swap, only a couple of people have ever done it.

 

[JayRolla]

From what I remember the last time I did it, it took about 5ish miles for the LTFT to kick in. Was stuck at 0, and then bam 19.5 and has never really moved since.

I realize I'm in uncharted territory with the MAF swap, only a couple of people have ever done it.

I have swapped mafs in Mitsubishi's and they have always needed compensation. I have seen as much as a 20% difference in fuel compensation.

 

[gamefreakgc]

I have swapped mafs in Mitsubishi's and they have always needed compensation. I have seen as much as a 20% difference in fuel compensation.

Alright, got a good amount of driving in with the stock MAF. It runs at +11% LTFT, will dip a bit under heavy throttle to +9%, and blip up to as high as +12%. So I am running lean. When I reset the EFI fuse after putting the original MAF in, with 0 fuel trim adjustments my AFR was 16-17, 16.8 at idle.

If I follow this math correctly, I should be able to run larger fuel injectors and the fuel trims can adjust? I'm adding a piggyback soon anyway, but should I add a larger fuel pump and larger injectors (roughly 10%-15% larger) to the list?

Also, the DENSO Lancer fuel pump you mentioned, is it a bolt on replacement? Apparently the Walbros are not.

 

[JayRolla]

Alright, got a good amount of driving in with the stock MAF. It runs at +11% LTFT, will dip a bit under heavy throttle to +9%, and blip up to as high as +12%. So I am running lean. When I reset the EFI fuse after putting the original MAF in, with 0 fuel trim adjustments my AFR was 16-17, 16.8 at idle.

If I follow this math correctly, I should be able to run larger fuel injectors and the fuel trims can adjust? I'm adding a piggyback soon anyway, but should I add a larger fuel pump and larger injectors (roughly 10%-15% larger) to the list?

Also, the DENSO Lancer fuel pump you mentioned, is it a bolt on replacement? Apparently the Walbros are not.

Your running lean but not maxed out. Now your ecu is working and adjusting like it should. Seems it fixed the issue. So you're ecu is keeping you at lambda. Again 14.7-16 afr is normal during idle and cruise.

If I was boosted and running smaller pulley I would run piggy back and larger fuel pump/injectors.

The denso also needs wired in. It's two wires. Just need soldered. People on eBay sell used densos with the plug. I run one and just soldered the pump into original harness.

 

[gamefreakgc]

Your running lean but not maxed out. Now your ecu is working and adjusting like it should. Seems it fixed the issue. So you're ecu is keeping you at lambda. Again 14.7-16 afr is normal during idle and cruise.

If I was boosted and running smaller pulley I would run piggy back and larger fuel pump/injectors.

The denso also needs wired in. It's two wires. Just need soldered. People on eBay sell used densos with the plug. I run one and just soldered the pump into original harness.

Wires are easy, I can do that. The Walbro instructions said to cut the hard line, etc, and didn't seem so simple anymore. You wouldn't happen to have a part number for the denso Lancer evo 8/9 190lph would you? Or is there only one option?

I guess what I meant about running lean is that since my LTFT are already having to add extra fuel, once I step on it in open loop my injectors don't have much more to give. That explains why I had to go 2 nozzle sizes higher than what the water injection company told me to use. I think fuel pump and injectors are on the list now!

 

[19963.4lsr5]

How old is your fuel filter?

If you have the older model you can watch your O2 sensor voltage on a scanner and see your relative AF based on the voltage.


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[JayRolla]

How old is your fuel filter?

If you have the older model you can watch your O2 sensor voltage on a scanner and see your relative AF based on the voltage.


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I believe he has a wbo2 installed.

 

[JayRolla]

Wires are easy, I can do that. The Walbro instructions said to cut the hard line, etc, and didn't seem so simple anymore. You wouldn't happen to have a part number for the denso Lancer evo 8/9 190lph would you? Or is there only one option?

I guess what I meant about running lean is that since my LTFT are already having to add extra fuel, once I step on it in open loop my injectors don't have much more to give. That explains why I had to go 2 nozzle sizes higher than what the water injection company told me to use. I think fuel pump and injectors are on the list now!

195130-3360. I believe it was just wires. Issue is this fuel pump is very hard to find now. I cant find it anywhere. You might want to go with the walbro 190lph and modify it in. Cutting the tube would be very easy.

 

[Scramble]

From what I've read the stock Evo 8 is only 160lph & the Walbro is 190. I have no idea what the stock 4R lph is but I guess the Evo 8 is enough because a few people here run it.

 

[SIKHILUXSURF]

Wires are easy, I can do that. The Walbro instructions said to cut the hard line, etc, and didn't seem so simple anymore. You wouldn't happen to have a part number for the denso Lancer evo 8/9 190lph would you? Or is there only one option?

trust me it isnt as hard when you have the pump out. i ordered a pump assembly to do this off the truck and just swap over when ready. i am using the 190LP that came with the urd kit. it is only a 1/2" that you are cutting because the pump is taller that the original factory pump. the only thing i didnt like it the fact that i had to splice the connector to the current wiring plug. so far i have disconnected the plug and dissasembled it in hopes of son splicing anything and just using connector pins to beable to reuse the plug and plug it back in creating to break in the winring as i dont know how much i trust a crimp connector in fuel vs. a solid connection. i will take pictures of it tonight and show you guys tommorow as i have the pump asemble at home ready to go and just waiting on the crimp terminals to finish and plug everything back in.

 

[19963.4lsr5]

I believe he has a wbo2 installed.

Yea, I wondered what year he's got because of the comment about going to the newer MAP sensor. Blowing a .88-.93 is good WOT if he has got the narrow band older 1v sensor. If he's able to already see the AF ratio than yep........


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