420A Fuel system maintenance.. Proper sized injectors for replacement.

[Mitsubi-doo]

I'm not turbo at the moment.
Header, full stainless catback, intake porting and soon to be 60mm throttle body.
Want to do fuel system maintenance, car has over 300k miles, but engine only has 1k miles on a fresh rebuild. So while I'm in there I'm doing a Walboro 190 (why not, gives me options later one), new fuel filter, and I want to do new injectors.

I like Fuel Injector Clinic, and want to support them. They have 420a specific injectors, but the smallest they offer is 365 cc injectors. Is that fairly close to OEM size?

I'm thinking with the free flow exhaust, and the intake mods it might be OK if slightly too much. I'm not shooting for much power but I want to improve on the car this year. And I want to use good parts.

This is my baby however slow it is but I'm hunting for increases when I can.

 

[jesse12345]

You'll need an adjustable fuel pressure regulator. I have 380cc and it was pretty rich at idle.

 

[Mitsubi-doo]

You'll need an adjustable fuel pressure regulator. I have 380cc and it was pretty rich at idle.

Thank you. I am assuming if its gonna be anything it's gonna be idle where fuel issues come up

 

[BLACK'98DSM]

If your injectors are in good working order, I wouldn't upgrade them yet. Your engine likely is not demanding more fuel yet.

You really need 2 components of data to monitor for making the determination. (1) A way to monitor air fuel ratio and (2) a way to monitor injector duty cycle. You can normally use a diagnostic tool to monitor the live reading of duty cycle. For the AFR, the only accurate way is to install a proper wideband sensor and gauge setup.

There was a time I had far more engine modifications than you, and I ran out of pump before injector. I never researched the flow rate of the stock pump, but I would imagine a 190lph is a little more stout. (Just read an older thread stating 160lph, but I cannot confirm this as a fact).
I went with a 255lph and never ran out of pump again. That's a good enough pump for a strong turbo setup, so I went a little overkill. What happened though is my mixture richened up significantly at WOT. The idle was almost perfect, bouncing between 14.7-15:1, but AFR dropped down to 11:1 around 5k rpm and WOT. That's too rich, as an N/A 420A seems to run best at around 12.5:1.

So if you were running lean at WOT, and the injector duty cycle was say less than 90%, a pump upgrade would likely be the solution. It will naturally boost fuel pressure and even raise the flow rate of stock injectors accordingly. The stock fuel injectors are rated at 235cc. At stock fuel pressure. Raising the fuel pressure will increase their flow rate a fair amount, and upgrading the pump will do this naturally.

When I finally did upgrade my injectors, I went with Fuel Injector Clinic's 365cc. The idle was richened to 12:1 and especially in the mid range rpm to 11-11.5:1. Rather than adjusting fuel pressure, I ramped up the dead times. Lots of adjusting was required but I achieved an idle at the stoichiometric ratio.

In conclusion:
- Rather than jumping the gun and spending money and time on injectors, I would rather you invest in the proper equipment to gather data. This way you can KNOW exactly what you need, rather than making assumptions.
- It sounds like you're enjoying modifying the engine and the car, so I'd highly suggest adding a tuning solution to your list of next modifications. MegaSquirt, MS2 or MS3. That way you can properly tune the engine to work with your modifications, rather than using trickery or guess work to achieve efficiency and proper engine performance.

If you need further clarification on anything or have further questions, just let me know.

 

[Mitsubi-doo]

If your injectors are in good working order, I wouldn't upgrade them yet. Your engine likely is not demanding more fuel yet.

You really need 2 components of data to monitor for making the determination. (1) A way to monitor air fuel ratio and (2) a way to monitor injector duty cycle. You can normally use a diagnostic tool to monitor the live reading of duty cycle. For the AFR, the only accurate way is to install a proper wideband sensor and gauge setup.

There was a time I had far more engine modifications than you, and I ran out of pump before injector. I never researched the flow rate of the stock pump, but I would imagine a 190lph is a little more stout. (Just read an older thread stating 160lph, but I cannot confirm this as a fact).
I went with a 255lph and never ran out of pump again. That's a good enough pump for a strong turbo setup, so I went a little overkill. What happened though is my mixture richened up significantly at WOT. The idle was almost perfect, bouncing between 14.7-15:1, but AFR dropped down to 11:1 around 5k rpm and WOT. That's too rich, as an N/A 420A seems to run best at around 12.5:1.

So if you were running lean at WOT, and the injector duty cycle was say less than 90%, a pump upgrade would likely be the solution. It will naturally boost fuel pressure and even raise the flow rate of stock injectors accordingly. The stock fuel injectors are rated at 235cc. At stock fuel pressure. Raising the fuel pressure will increase their flow rate a fair amount, and upgrading the pump will do this naturally.

When I finally did upgrade my injectors, I went with Fuel Injector Clinic's 365cc. The idle was richened to 12:1 and especially in the mid range rpm to 11-11.5:1. Rather than adjusting fuel pressure, I ramped up the dead times. Lots of adjusting was required but I achieved an idle at the stoichiometric ratio.

In conclusion:
- Rather than jumping the gun and spending money and time on injectors, I would rather you invest in the proper equipment to gather data. This way you can KNOW exactly what you need, rather than making assumptions.
- It sounds like you're enjoying modifying the engine and the car, so I'd highly suggest adding a tuning solution to your list of next modifications. MegaSquirt, MS2 or MS3. That way you can properly tune the engine to work with your modifications, rather than using trickery or guess work to achieve efficiency and proper engine performance.

If you need further clarification on anything or have further questions, just let me know.

That is a interesting observation. I much appreciate all that input, I doubt I'm running out of much fuel, with my setup but I would like to refine it and make every small improvement I can. And fuel maintenance was on the agenda. Im definitely wanting a good fuel pump. And I like the idea of adjusting the fuel pressure. The 190 supposedly flows 400hp but what set up did you run to adjust your 255?

I'm still in the process of gathering data, I want a good wide band. Theres a port on my header im not using but its external threads id like to find something to modify to use. But I have my old snapon solus ultra scan tool I run with the mitsubishi adapter I'm using.
I am thinking ms2 with a ms transmission controller ( if I stay auto, I cant count how many auto transmissions I've rebuild)

But I found a tuning solution for the oem ecm I want to try first and see how good it is
If it doesn't work well for me it's worth the experience. But I have to brush up on my computer skills .
The only issue from people using it on our cars is boosted fuel maps I hear. Being 1 bar it doesn't like going positive pressure. But I think there is a way to use a 2 bar at least and build a new fuel map around it.
And it's very more computer guy type stuff.
That and you'll have to make an adapter to tap into the secondary diagnostic port.

Turbo is in the future, but not right now just making improvements where I can.
I'm spending alot of money going all out on a forged, turbo Lancer.