Fuel Injector and Fuel Pump Upgrade? [1G]

[Oblivion02]

Hey guys,

I checked out my fuel injectors yesterday, and the rubber tip of two of them is broken. I was considering a fuel injector upgrade, but I heard that i'd have to upgrade/update my ECU. Is this true? How does this work?

I was also considering a fuel pump, but not sure which pump to get.

What else should I get while I'm working in the FUEL department? Any recommendations?

 

[kenamond]

First of all, can you post a picture of your broken fuel injector tips?

Next, if you replace your stock injectors with upgraded, larger injectors, you need to do other things as well.

Injectors 101:

The injectors connect between a fuel rail and the intake ports on the head of the engine. The fuel pump provides high pressure fuel to the fuel rail on the passenger end. The car expects the pressure in that fuel rail to be a certain amount, so there is a fuel pressure regulator (FPR) on the driver's side end of the fuel rail. It opens just enough so that the fuel pressure in the rail is the correct value, and the extra fuel is recirculated back to the gas tank.

Injectors are just quick-acting valves that open all the way when told to and snap all the way shut otherwise. When they are open, they let that pressurized fuel in the rail pass through the injector. The tip of the injector is designed to form a fine spray of fuel so that it can evaporate or mix very well with the air.

The injector is calibrated to flow a certain volume of fuel over a certain period of time (like cubic centimeters per minute or cc/min). But this is based on having a certain pressure difference on each end of the injector. So if the FPR is doing its job, the pressure upwind of the injector is always a certain amount higher than the pressure in the inlet port of the head at the other end of the injector where it is squirting the fuel.

But we have turbocharged engines, so the pressure in the intake port of the head is boosted. In order to keep the fuel rail pressure a fixed amount higher than the inlet port pressure, a vaccuum line is used to let the FPR correct the fuel pressure so that it is always a constant amount higher regardless of the boost pressure in the inlet ports (43psi in a 2g and 38.5psi in a 1g if I remember correctly).

The ECU knows all about how much air is going into each cylinder per revolution, and it knows what air:fuel ratio (AFR) it wants, so it knows how much fuel it needs to deliver. It tells the injectors to open for a specific duration called the pulse width (it provides a voltage pulse that causes the injector to open all the way). It knows that with the correct fuel pressure and the stock injector type, opening the injector for that time will deliver precisely the correct mass of fuel.

Now if you get a larger set of injectors, they flow more fuel per second at the same pressure than a smaller injector. So if all you do is change to larger injectors, the ECU doesn't know this. So it still pulses the injectors the same way. But the larger injectors flow more fuel now, so you inject too much fuel, the car runs really rich, and power goes out the window.

So if you go to larger injectors, you need to do something to either reprogram the ECU or somehow deceive it such that it thinks that it should pulse the injectors a shorter period of time. If you get a programmable ECU (EPROM ECU), you can buy a new chip for it that is designed for a certain size of larger injectors. Or you can get DSMLink which allows you to program the chip yourself and change it if you need to over and over until you're happy or until you change something else on the car. If you get S-AFC, you intercept some of the sensor data, manipulate it, and the give it to the ECU, and the manipulation is adjusted until the car runs properly (until your lies cause the ECU to do what you want it to).

Another problem is that the stock fuel pump is *just* big enough for the stock power levels. It is limited both by the fuel pump size as well as the voltage supply in the stock wiring harness. If you increase the demand on the fuel system (usually because you're running higher boost which sends more air through the motor which must be properly mixed with enough fuel, so you need more fuel), you can hit the limits of the fuel pump. When this happens, the pressure in the fuel rail starts to drop below what it's supposed to be. When this happens, the whole expectation by the ECU of how long to pulse the injectors is no longer valid; pulsing the injectors the same duration but at lower fuel pressure results in less fuel flowing through the injectors over that pulse duration. That results in a lean condition in the combustion chamber (AFR is too high) which is dangerous for the engine.

So usually, you rewire the fuel pump to improve the voltage. That buys you a bit on the stock fuel pump. If you push performance farther, eventually, the fuel pump is maxed out and it needs to be upgraded to one that can flow much more fuel.

However, once you go to a larger fuel pump, that FPR on the end of the fuel rail becomes a limiting factor. It's supposed to let just enough fuel out of the rail (and back to the fuel tank) so that it maintains the proper pressure differential between the rail and the inlet ports, but when a bigger fuel pump is supplying much more fuel to the rail, it overwhelms the FPR and the rail pressure goes too high (called FPR overrun). In that case, the higher pressure results in too much fuel getting delivered in the pulse width, and the car runs rich, which decreases power. So usually, folks get an adjustable FPR (AFPR) when they upgrade their fuel pump, and these can handle the higher fuel flow rate and also let you dial in the desired pressure (43psi for 2g, 38.5psi for 1g) and usually include a pressure gauge to facilitate this adjustment.

So with all that said, you now need to decide what your goals are for performance and then search to find out what all parts you need to replace so that you can do that.

 

[tqmx1]

Not so many words but I told him that yesterday

 

[Calan]

Is that stickied somewhere?

If not, it needs to be.

 

[Oblivion02]

@Kenamond ->Again, great post.
@tqmx1 -> I know, I just didnt know how it worked.
@calan -> Yes it should.

My goals are just to get the max out of my car, stock. I do not want to upgrade the turbo, or anything like that. Just squeeze the most out of it. I was thinking about increasing my turbo boost to 15psi, which should be OK for my stock BOV. But i figured, since I'd be sending more air into the engine, I might need more fuel. So now I'm stuck with this problem. Because I do not NEEED soo much fuel, since I will not be doing any major upgrades, or pushing my car over 15psi boost. How much is needed if I just want to keep it stock and run at this boost level? I do not know. Recomendations? I'm thinking about just buying replacement injectors, and a replacement stock pump, and maybe rewire it? Is this necesarry? Again, all I want to do is increase my boost to 15psi, keeping most things stock, no BIG upgrade.

 

[kraka]

All you need is a Walbro 190lph fuel pump or a simple rewire kit. You will be able to safely run 15psi on the stock turbo.

 

[Oblivion02]

Won't I still need a pressure regulator with that? Or since its close to what a stock pump sends, I wont have any problems?

 

[16gpoweredgsx]

Won't I still need a pressure regulator with that? Or since its close to what a stock pump sends, I wont have any problems?

Most of the time the walbro 190 won't cause any problems with the stock regulator, but their has been a few posts I've read where they still ran a little rich at idle.

 

[outkastracing]

if your lookin to keep it stock just do the free mods for the dsm you can safely run 13-15 pounds until your turbo gives up with just a simple rewire... i did that on my first dsm and ran it for about a year before the great 14b gave up on me

 

[Oblivion02]

Will a simple rewire send in enough gas for the extra air the 15 psi boost + K&N OEM Replacement filter will be taking in? If so, I could just purchase some stock fuel injectors, and rewire the pump.

What do you guys recommend? Stock pump simple rewire? Or new walbro pump with stock regulator? Walbro + fuel regulator? The injectors, i'ma keep them stock, just to avoid the ECU problem.

 

[nfernotalon]

Just buy the 190 your stock is old anyway and wouldnt hurt to replace it, change your fuel filter too and rewire the fuel pump. Stock injectors are fine for what you want, you dont need a FPR with the 190

 

[Oblivion02]

Yeah. Fuel filter is part of the tune-up I'm doing. But the thing is... wouldn't the WALBRO 190 need a fuel regulator? I don't want to take any chances. I want to make sure it works properly.

By the way, if it does need a fuel regulator, can someone point out to a good and cheap fuel regulator?

 

[nfernotalon]

99% of people here run the 190 without a FPR with no problems..

 

[Oblivion02]

If I rewire the WALBRO 190 Fuel Pump, wont it send TOO much gasoline? or did you mean REWIRE the STOCK pump?

 

[nfernotalon]

Rewire the 190 too, your stock FPR can still handle the 190 but not the 255

 

[Oblivion02]

Isn't rewiring to send MORE gasoline? If I rewire the 190, won't I send WAY TOO MUCH gas?

 

[nfernotalon]

Get a FPR then.. you dont need it but get it anyways if you want.. rewire the fuel pump because at WOT the voltage goes down on it and doesnt work like it should

 

[kraka]

Rewiring the voltage supply just helps keep a more consistent flow of fuel. It may cause you to run richer but it is worth it to do anyway. My car didn't need an AFPR with my walbro, and I am not currently using one either for my rewired walbro 255

 

[kenamond]

Here's my opinion/suggestion.

If you're going to be changing the FP, why not upgrade to a 190? But either way, rewire it. The pump is drinking electricity through a coffee straw, and this isn't a problem on a stock motor but will get to be a problem when you increase the boost and are at higher rpm and higher boost; the FP will not be able to maintain the correct fuel rail pressure. And you'd want the 190 to have ample voltage. The rewire is really easy to do and is very well documented. I have a 2g, so I'd get a 2nd opinion on rewire from a 1g owner.

Replace the fuel filter. If it's clogged, that just gets in the way of fuel pressure.

Get a logger. 1g owners have the luxury of a simple logger cable (called an interface) that you can buy super cheap (2g interface is $90) or even make it yourself if you want to (search for the palm'n'stein web site, it has a link to the how-to if you're interested). And the PDA can be had for dirt cheap (get a refurbished one off of eBay). My wife found a Palm IIIe or something for $1 at a 2nd hand store. And the logger software is free (OBDgauge, MMCd, or Palm'n'stein are all free - I'd recommend OBDgauge or MMCd from what I've read). The logger will tell you if you're running safely at increased boost levels.

If you find that you're overrunning the stock FPR a bit, decide if you want to upgrade to an AFPR (most folks use an Aeromotive AFPR with liquid-filled fuel pressure gauge). It's something like $200. If you can live with the low-rpm overrun on the 190 fuel pump, then live with it. But if you get the AFPR, you're one step closer to larger injectors, turbo upgrade, more power, etc. Almost everyone on this forum will tell you that once you get wrenching on the car and start getting more power, you'll want even more.

But don't forget to do all of the other maintenance in the Stage 0 mods section. If your car has problems and you start increasing boost, things will break faster.

If the shop hasn't fixed the injectors yet, you might want to make sure they replaced the insulators (some call them seals) between the injectors and head. They're a super cheap part, but the rubber turns to like a plastic over time from the heat, and they'll start to leak. Since they're sealing the intake ports against the injectors, they see boost pressure, so leaking insulators is a boost leak...and it's very common. It's not too hard to change them, but if the mechanic is in there already, they will already have the insulators in the palms of their hands and would add no time to put in new ones. Save you an hour of pulling the fuel rail and injectors and replacing the insulators.

Good luck!

 

[Oblivion02]

I've already done some maintainance in the car. I took advantage of it being in the mechanic, and had alot of the things updated. I bought new:

Spark plugs, spark plug wiring, timing belt, balance shaft belt, timing belt tensioner, water pump, oil filter, and synthetic oil.

Still to be updated list:
Thermostat
PCV Valve
Water Hoses
Build My Own MBC
Aftermarket Boost Gauge
Fuel System Upgrade [pump, filter, palm, logger cable, possibly an AFPR]

It makes sense, the fact that I'd probably want MORE and MORE power. But that wont be the case, at least not for now. I do not want my parents getting paranoid. Since I'm 18, I had a hard time convincing them to get me a 1G Turbo Eclipse in the first place.

Besides, even though bigger injectors means more power, but it would also mean less MPG wont it? I just want to get the max out of my car at 15psi. If the walbro 190lph fuel pump + rewire + fuel filter will get me the gas I need to properly mix with the air that the K&N OEM Replacement Air filter will be taking in, plus the 15 psi boost, then I'll be fine with that. I just don't want to be missing any gas, or putting in TOO much. Trying to get the max out of it, just at 15psi.

 

[kenamond]

I've already done some maintainance in the car. I took advantage of it being in the mechanic, and had alot of the things updated. I bought new:

Spark plugs, spark plug wiring, timing belt, balance shaft belt, timing belt tensioner, water pump, oil filter, and synthetic oil.

Still to be updated list:
Thermostat
PCV Valve
Water Hoses
Build My Own MBC
Aftermarket Boost Gauge
Fuel System Upgrade [pump, filter, palm, logger cable, possibly an AFPR]

It makes sense, the fact that I'd probably want MORE and MORE power. But that wont be the case, at least not for now. I do not want my parents getting paranoid. Since I'm 18, I had a hard time convincing them to get me a 1G Turbo Eclipse in the first place.

Besides, even though bigger injectors means more power, but it would also mean less MPG wont it? I just want to get the max out of my car at 15psi. If the walbro 190lph fuel pump + rewire + fuel filter will get me the gas I need to properly mix with the air that the K&N OEM Replacement Air filter will be taking in, plus the 15 psi boost, then I'll be fine with that. I just don't want to be missing any gas, or putting in TOO much. Trying to get the max out of it, just at 15psi.

Sounds like a good plan. If the timing job hasn't yet been done, I'd also recommend replacing the idler and tensioner pulleys themselves, as they tend to come apart (not good). I don't know much about details, which parts are good, etc., so you should search around.

As for gas mileage, your foot on the gas pedal is what controls that. I'm running 15psi boost, but I still get 29mpg highway. It's when you tromp it all over the place that the gas gauge needle starts moving too fast. It will depend on your tune, but I'd only worry about gas mileage if you don't think you can control yourself. If I tromp it around town, I can get 19mpg, but I usually get 22-24mpg around town. Also, keeping the car well maintained will help with mileage, such as making sure you don't have boost leaks.

 

[Oblivion02]

So for now, walbro fuel pump + stock injectors + rewire. Eventually, once I save up enough cash, get an AFPR. Then once I have that AFPR, I have the door open for the bigger injectors like you guys said.

I'm considering maybe just buying used fuel injectors, or just buying 2 stock replacements, since eventually i Will get bigger injectors.

But again my concern comes up. Won't I flood the engine with too much gasoline when I install the walbro 190lph fuel pump + stock injectors + rewire?

[By the way, would a FUEL RAIL be something to upgrade as well? I have no idea what it does... but noticed its in the performance FUEL parts area.]

I also noticed that some of the prices on some "performance" parts are quite expensive. I never thought a boost gauge would cause soo much. Do you guys think its worth investing in it, as far as my GOALS go? It's going to be my drive-everyday car, not a race car.

 

[Oblivion02]

Also, any specific recomendations as far as Fuel Injectors[size, and brand], Fuel Filters, and AFPR come? What do you guys recommend for my goals?

 

[97gstjosh]

Also, any specific recomendations as far as Fuel Injectors[size, and brand], Fuel Filters, and AFPR come? What do you guys recommend for my goals?

Ok for fuel injectors I thought you were just going to buy OEM ones for now?
Later on when you want to upgrade your turbo and you know what turbo you are getting
thats when we can tell you fuel injector sizes. But go with FIC injectors when you upgrade
your turbo.
For a fuel filter use the stock one for now. I still use the stock one its perfectly fine.
For a AFPR kit here you go: Best one around its even cheaper if you dont want SS lines
ImportEvolution.com - Import Performance Parts, DSM, WRX, Supra, Honda
Heres a link for a AFPR gauge:
ImportEvolution.com - Import Performance Parts, DSM, WRX, Supra, Honda

Hope this helps you

 

[Oblivion02]

I was planning on sticking to stock injectors, but if I'm going to buy an AFPR, thought I should have gotten slightly bigger injectors.

But anyhow, since I do not have much cash available now, I will probably go with the stock fuel filter, stock injectors, and walbro 190lph rewired. I wanted to do this to avoid problems when I increase my PSI, but to do that, I need to purchase a boost gauge [which are expensive... If anyone has recomendations please let me know], then build my MBC, then upgrade the fuel system, then increase my boost. So until I can afford a boost gauge, my upgrading is pretty stuck for now. I gotta focus on finishing the tune-up, get it running, and then upgrade. Its just I'm building a small upgrade list for things I want to eventually upgrade. Thanks for your time, and keep the recommendations comming please. I'll post my current list of upgrades just in case it helps anyone out, maybe someone with similar goals.