RTEK 1.8, 4 x 750cc injectors, Apexi Neo MAXED - STILL LEAN UNDER WOT
maybe it failed because they were running at max dutycycle..
No need in getting even bigger injectors, just replace with the same ones and check fuel pressure after installing.
Even 650cc worth of sec injection would not lean out that much with proper fuel pressure.
No need in getting even bigger injectors, just replace with the same ones and check fuel pressure after installing.
Even 650cc worth of sec injection would not lean out that much with proper fuel pressure.
Thread Starter
Joined: Jul 2004
Posts: 766
Likes: 1
From: corvallis, or
Jee wizz... Ya think?
Of course no one will agree to that as "there's no way your maxing 4x 750cc injectors"
... And Injector Dynamics has confirmed the serial numbers on my injectors ARE authentic and now are arguing that the specific gravity of the test fluid used to flow the injectors MUST be differnt than gasoline even though the RC injectors flowed within 1% of spec on the same rig.. At the same time.
Of course no one will agree to that as "there's no way your maxing 4x 750cc injectors"
... And Injector Dynamics has confirmed the serial numbers on my injectors ARE authentic and now are arguing that the specific gravity of the test fluid used to flow the injectors MUST be differnt than gasoline even though the RC injectors flowed within 1% of spec on the same rig.. At the same time.
Joined: May 2006
Posts: 3,881
Likes: 3
From: Jacksonville, Tampa & Tallahassee
...This
Also, perhaps I missed it but i don't see what PSI they performed this test at... that is the single biggest determining factor in observed injector flow and not all injectors are factory rated at the same pressure. For example, GSL-SE "680's" are rated at like 38 psi, while Siemens 750's are rated at 43.5 psi. So if you test the siemens injectors at 38 psi they would "fail" but the denso's would be spot on. Coincidentally at 40 psi they both flow around 720cc's. Not saying this is what happened with your test, but something to consider.
Something else to consider is if they are in fact bad, what caused the failure? Was it sediment causing an obstruction or physically damaging the components or was there some sort of electrical failure?
I'm gonna go out on a limb and suggest the problem is physical in nature, which brings us back to a point that has been made numerous times in this thread, but you still don't seem to grasp......CHECK YOUR TANK. Is it that hard to look inside a first gen tank? is it that hard to believe that a 30 year old tank might not be in pristine condition? (I apologize if at some point you mentioned having the tank cleaned, cuz if you did, I certainly didn't see it)
...Because you aren't. Also that statement makes the assumption that your fuel system is functioning properly.
Also, perhaps I missed it but i don't see what PSI they performed this test at... that is the single biggest determining factor in observed injector flow and not all injectors are factory rated at the same pressure. For example, GSL-SE "680's" are rated at like 38 psi, while Siemens 750's are rated at 43.5 psi. So if you test the siemens injectors at 38 psi they would "fail" but the denso's would be spot on. Coincidentally at 40 psi they both flow around 720cc's. Not saying this is what happened with your test, but something to consider.
Something else to consider is if they are in fact bad, what caused the failure? Was it sediment causing an obstruction or physically damaging the components or was there some sort of electrical failure?
I'm gonna go out on a limb and suggest the problem is physical in nature, which brings us back to a point that has been made numerous times in this thread, but you still don't seem to grasp......CHECK YOUR TANK. Is it that hard to look inside a first gen tank? is it that hard to believe that a 30 year old tank might not be in pristine condition? (I apologize if at some point you mentioned having the tank cleaned, cuz if you did, I certainly didn't see it)
...Because you aren't. Also that statement makes the assumption that your fuel system is functioning properly.

If your fuel pressure is too low, the injectors will flow way less then they should..
It is only when you go WOT, which still makes me come back to a fuel delivery issue, pressure or flow
Thread Starter
Joined: Jul 2004
Posts: 766
Likes: 1
From: corvallis, or
New secondary fuel injectors installed... Much better... Mid to low 11's under WOT and AFRs dropping to mid 10s by 6k rpms.. Fat and happy... Could probely tune some fuel out with Neo though
What's "too rich"?
What's "too rich"?
Joined: Mar 2001
Posts: 31,837
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From: https://www2.mazda.com/en/100th/
it will run leaner, but you run the risk of having it just fail one day. it'll be from preignition, but it won't have any symptoms.
Thread Starter
Joined: Jul 2004
Posts: 766
Likes: 1
From: corvallis, or
After installing the new injectors, i started over on the Neo with ALL correction OFF. I'm now running +30% from 4000-5000rpm to keep me in the low 11's AFRs. Than -15% from 6000+rpm to keep from full rich (10:1 is full rich on the AEM wideband)... So with -15% im hovering in low 10's. ZERO misfires or ANY hesitation... Pulls HARD and LOUD... I was doing 3rd gear pulls to maintain traction and consistant load... Was shifting to fourth and hitting 110mph faster than i could stomp the pedal, glance at boost gauge to make sure no creep than look at my AFR's long enough to make sure they're steadily dropping to readable numbers before shifting gears and letting off... I love my car
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