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Fuel Injectors

8K views 46 replies 9 participants last post by  madmatt2024 
#1 ·




Anyone want to tell me the difference?

John
 
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#13 ·
So.....resurrecting my own thread!:p

I've read two schools of thought on injectors. One being, like Marclar. where they caution you that you should match the injector output to the MAF while another, that being MadMatt, claims that some of the ZX2 guys said that the 19 lb injectors have been found to improve power and mileage.

I was at the yard the other day and found a 1990 Mustang GT. I yanked the injectors which happened to be the yellow tops that MadMatt was talking about, I think, and have two questions.

Is there anyone that can say that they have experienced in real time the claim that 19 lb injectors do improve gas mileage and power or is it like Marclar says and the injectors should be matched to the MAF? I realize that just because there is the possibility of more flow from the injectors it doesn't mean that your car will see that bump in power since the engine needs what it needs and no more but if this is in fact true then I may install the set of injectors I pulled off the Mustang but I'd like to get a little more conformation before I try this.

Also wanted to confirm that the injectors I pulled are in fact the 19 lb ones that have been mentioned.

John
 
#14 ·
keeping in mind that the factory pcm is programmed to run slightly on the rich side from the factory... so what will happen is if you just slap larger flow injectors in, it will run a LOT richer. this has multiple side effects.. first off it has a chance of cooking the cat due to excessive fuel burning in the exhaust. creates more carbon deposits, and dirties your oil faster. IF it was a diesel, then yes, adding more fuel would help. but not in gas applications.
in order to make 'more power' and ' better fuel mileage' the idea is to lean out the mix and not waste the fuel.

i did personally experiment with this back in the 2004-2006 era. my findings were as such above. the ecc4 pcm is pretty dumb, and the fuel trims will lean out over time correcting for the extreme rich condition to a point. keeping in mind the 0-5v maf signal is designed to reflect a linear voltage porportional to air mass.. so a 19# injector will give slightly more fuel at the same voltage point than a 16#. the whole idea of swapping to the 19# vs 16# was to get the 4 nozzle discharge vs the single conical nozzle.. this gives better atomization and thus efficiency, not from adding more fuel. that is why the maf needs to be paired to the injector flow rate.

yellow top injectors from disgustang are 24#. you can refrence the part numbers on the injectors, there is a table somewehere in the webs that shows the flow per PN
 
#19 ·
Thanks for the lesson. So, other than my engine having been upgraded N/A or turboed the stock E6(?) Injectors are what would be best in regards to what the computer likes?

The injectors I have in the car currently are the 4 hole type so I guess I already have the recommended injector size. I put installed them as a temporary fix since they were pulled from another Escort I was pulling parts from at the yard. So far they've been fine but I'm not sure how long they're going to keep working. I figured if the 19 lb injectors wete going to improve mileage and power why not. I needed to get in there anyways.

John
 
#15 ·
The original injectors on my '92 wagon are four hole, as is the spare set I picked up from a '91 wagon. From my research these would have been 14lb/hr injectors.

As I understand it, at WOT the PCM defaults to open loop, generally running quite rich to be on the safe side, because the narrow band Oxygen sensor doesn't work in a rich (or lean) mixture. Does this mean with larger injectors the mixture would be proportionally richer, or does the brain know that it has been shortening the pulse recently because of the bigger injectors, and will only enrich the mixture the usual amount?
 
#16 ·
the pcm has the ability to control fuel trims, to an extent. nothing like obd2 ST/LT. it will lean out the mix as far as it is allowed to over time, could take weeks. but it wants to exist in its programmed range, and could throw a rich code. the difference between 14lb and 19lb for example is a sizeable difference. meaning 14/19lbs of fuel per min, which i believe a gal of gas is like 8lb,. so 2gal per min vs 1.75. so that extra quarter lb of fuel is effectively wasted.. (assuming WOT condition, but still applies in normal driving range) if it was a turbo diesel, then that extra .25 lb of fuel WOULD make a difference.
 
#22 ·
What is OBD2 ST/LT? novanutcase is running a (2000?) Zetec motor that has OBD2. I have a similiar interest in this because I am running a 98 Zetec in my 98 Wagon and may eventually be looking at a throttle body upgrade. I already plan to change my injectors from the current single pintle to 4 hole of the later zetecs or I have a source that recommends a set from a Volvo app. that should work well.
 
#21 ·
the factory fuel system even with 16# injectors is good for any bolt on-s. even in a turbo setup you can run 4psi or so depending on the turbo CFM capabilities with a draw-thru setup using stock injectors and maf.
if you indeed are running or are going to run the 19# skinny 4 port injectors, you can just get a maf and connector from a 97/98 split port car and wire it in. some of the wires are backwards though. cant remember off hand which is wich but i think there is a writeup, or i can look on mine at home.
 
#26 ·
Yes, you should. You are also probably hurting performance running a turbo cam on an N/A motor.
 
#34 ·
Nice chart, it would be good to have the Escort injectors in there as well. I think the 1.9 LX ones are 14#.

Another thing to keep in mind is that there are two resistance (or impedance, I don't recall for sure) styles of the EV1 injector as used on the LX 1.9 cars and the early HO 1.9s, and they are not interchangeable electrically even though they are, physically.
 
#35 ·
Another thing to keep in mind is that injectors for an engine with 2 intake valves (Cobra Mustang, Navigator, etc.) will most likely have a V-shaped spray pattern, making them incompatible with a single intake valve engine like the CVH. You'll end up spraying most of the fuel onto the walls of the port instead of atomizing it.
 
#37 ·
Short answer, no. Just get your tune modified for the new injectors.
 
#41 ·
Oh, it sounds like whoever did the tune locked it on you. Only the person who originally made the tune for you can modify it, is that an option?

I think the way they read the duty cycle is within the tuning software itself before loading the tune to the car, which is different than what you can do with an OBDII scanner.
 
#44 ·
Oh, it sounds like whoever did the tune locked it on you. Only the person who originally made the tune for you can modify it, is that an option?

I think the way they read the duty cycle is within the tuning software itself before loading the tune to the car, which is different than what you can do with an OBDII scanner.
Person who tune it is a tuner god but won't even consider talking about tuning our turds. He is highly respected in the industry and asks for big money.

All tunes are locked unless you have pro racer package and have a editable file.

Sent from my LG-H872 using Tapatalk
 
#43 ·
It depends on how much bigger the injectors are. For instance, going from 19lb to 30lb probably won't make a difference but going a 100lb/1000cc injector would.
 
#47 · (Edited)
I would honestly look into getting an actual dyno tune. A mail-in tune will never be as dialed in as a true dyno tune. Best of all, if something isn't right you can always go back to a brick and mortar location rather than waiting or getting ghosted by some guy on a forum. There is actually a guy that used to be on here years ago (NYinThaBuilding05) that now has his own tuning shop a couple hours away from me. Back in April his shop broke the world record for power for an MKV Supra. I'm not sure if he's doing mail in stuff right now though.
 
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