19# injectors sans chip

[RobE30]

My engine is an m20 w/ a shrick 272/284 cam, IE shorty headers, no cat and supersprint exhaust. I am currently running a 173 ecu stock. In the future I am planning on a "chip" of some sort, poss the miller conversion. What injector would benefit me the most @ this time?

[nando]

is it a stock 2.5l or is it a 2.8l?

if it's a 2.5l, you'll want 19# and the miller conversion for a proper tune. if it's a 2.8l then look for 21# injectors, the miller conversion at minimum and standalone engine management for best results. no off the shelf chip is really going to give you a good tune though.

[downernsp]

is it a stock 2.5l or is it a 2.8l?

if it's a 2.5l, you'll want 19# and the miller conversion for a proper tune. if it's a 2.8l then look for 21# injectors, the miller conversion at minimum and standalone engine management for best results. no off the shelf chip is really going to give you a good tune though.

And just to add a bit, if one has 19# let miller know so they can provide you with the new chip that comes with the MAF to support the increase of air and 19#. As to if you don't they give you the stock chip that comes with MAF instead of the new chip as stated above.

[T Verdier]

nope, that has nothing to do with it

design 2/3 just have more pintles and a far superior spray pattern

electically, they are exactly the same. The ECU cannot tell them apart, except that with O2 sensor feedback it has to dial back the pulsewidth to reach it's 14.7:1 target.

the ECU has long term and short term fuel trims. the short term trim adjusts the injector pulsewidth in real time to keep it as close to 14.7:1 as possible. the long term trim adjusts a global base pulsewidth value based on how much it has to adjust for the short term trim. It only works with a functioning O2 sensor.

So all these guys saying that there getting bad gas millage and that it runs rich have bad o2 sensors right? because the ecu should correct it no matter if you have #14 #17 or #19 it should always put the same amount of fuel. but the 17 and 19 have better spray patterns or "atomization"
so why do I need a chip that's ment for the correct injectors? Or do I.
I can't get more fuel without more air and the stock intake system isn't gonna get me much more.

P.S. I like how this is in general discusion. Lol

[Wh33lhop]

So all these guys saying that there getting bad gas millage and that it runs rich have bad o2 sensors right? because the ecu should correct it no matter if you have #14 #17 or #19 it should always put the same amount of fuel. but the 17 and 19 have better spray patterns or "atomization"
so why do I need a chip that's ment for the correct injectors? Or do I.
I can't get more fuel without more air and the stock intake system isn't gonna get me much more.

P.S. I like how this is in general discusion. Lol

The idea behind the bigger injectors is that 1) they'll atomize better, and 2) the stock injectors are running a high duty cycle when you chip your car. High duty cycle in general is bad, as injectors are not as consistent or predictable to the ECU at a high duty cycle than they are at a lower one.

Then, there's 3) that you'll need more fuel down the line whenever you do anything else to your car. Stock 14# M20 injectors can't really support much more than stock power.

As for the fuel economy, I'll leave that to Nando.

Also of note, after adjusting my idle trim screw to full lean (stock M20 except 19#ers and Mark D) the infamous "idle CEL" went away and I passed smog with flying colors.

[T Verdier]

The idea behind the bigger injectors is that 1) they'll atomize better, and 2) the stock injectors are running a high duty cycle when you chip your car. High duty cycle in general is bad, as injectors are not as consistent or predictable to the ECU at a high duty cycle than they are at a lower one.

Then, there's 3) that you'll need more fuel down the line whenever you do anything else to your car. Stock 14# M20 injectors can't really support much more than stock power.

As for the fuel economy, I'll leave that to Nando.

Also of note, after adjusting my idle trim screw to full lean (stock M20 except 19#ers and Mark D) the infamous "idle CEL" went away and I passed smog with flying colors.

alright so more overhead. should I go with17s or 19s I don't think I'll ever need 19s.

[nando]

So all these guys saying that there getting bad gas millage and that it runs rich have bad o2 sensors right? because the ecu should correct it no matter if you have #14 #17 or #19 it should always put the same amount of fuel. but the 17 and 19 have better spray patterns or "atomization"
so why do I need a chip that's ment for the correct injectors? Or do I.
I can't get more fuel without more air and the stock intake system isn't gonna get me much more.

P.S. I like how this is in general discusion. Lol

generally, yes. that or something else isn't right. Just think about the ratio oif poorly running M20s to highly maintained ones. People can't get them to run right in stock form, much less with mods. I've also done 19# with the stock chip, years ago, and my fuel economy was unchanged. car ran perfectly.

a chip meant for the injectors is already setup with the right base PW. so you don't have to wait for long term trims to kick in before the car runs correctly. Plus you usually get a better tune in general that way.

if you just have a stock M20, the 17# M50 injectors are a better choice. 19# don't get you very far, anyway.

[nando]

Also of note, after adjusting my idle trim screw to full lean (stock M20 except 19#ers and Mark D) the infamous "idle CEL" went away and I passed smog with flying colors.

what year was it? later ones don't have any idle trim screw that I know of, I think it's completely blocked off.

[Wh33lhop]

My car's running pretty well, and my gas mileage definitely went down after the injectors. However, I wouldn't really blame it on the injectors so much as me trying to chirp third everywhere I go.

The car is an 87. When you say completely blocked off, you mean impossible to get to, or you've got to punch through a plug? My car had already been screwed with by some dumbass who put a blue plug in there (and used SAE bolts on my crank pulley), so we just got rid of the plug altogether and left it accessable.

[nando]

I mean there's nothing there, it's all cast aluminum.

[Wh33lhop]

I mean there's nothing there, it's all cast aluminum.

Huh. Well in that case, guess I'm lucky. ;)

[nando]

maybe it should be the 87 325i AFM & 19# injector swap injectors instead of the M30 AFM swap :p

[Wh33lhop]

maybe it should be the 87 325i AFM & 19# injector swap injectors instead of the M30 AFM swap :p

...Maybe it should just be the MAF conversion. ;)

[RobE30]

@ this time my car is a standard 2.5. Eventually I plan on going to 2.7 w/ euro 11:1 pistons etc (thats far off).