# Is stock ECU gonna handle 550cc injectors?



## alex12582 (Sep 30, 2003)

Like the topic says. 
Thanks


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## TheVodKA (Sep 19, 2002)

Stock ecu can't compensate for any injectors besides stock for most ecus, and definitely for any nissan I know of (I think DSMers upgrade their injectors w/o any other fuel management, but not sure)


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## holy200sx (Jan 8, 2003)

well think of it this way

an injector has a flow rate of 1-100%
Stock 157cc injectors flow at lets say X%, without an upgraded ecu if you installed 550cc injectors, your ecu would make them continue to run at the same X% flow... so you would be flowing.. oooh. 3x more gas than normal... 
with an upgraded ecu, or SAFCII, you can controll the flow rate, and change it from X% to 1/3X%

if you kinda understand waht im saying


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## alex12582 (Sep 30, 2003)

So, the engine will run very rich at idle?


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## TheVodKA (Sep 19, 2002)

Not just at idle but throughout the whole powerband.

And btw, holy200sx, good explanation on the functions of the duty cycle in relation to the ecu.


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## sersr20dk (Oct 15, 2003)

the car will run like shit, it might not even run, it might just stall alot, more than likely it will just dump too much fuel and stall, why do you ask this question, becuase there are ways around it, if you have a setup that requires 550's then the 350 or so for an e-manage shouldn't be that bad. without a s-afc or e-manage the ecu has no way to tell that the injectors are any different, the oxygen sensor will try to compensate but won't help when cold and at wot.


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## Trav4011 (May 1, 2002)

It will not handle that large of an injector... about 38lb(400cc) is the max..
Travis


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## jbanach77 (Jun 11, 2002)

i'm sorry if i over looked this, but what kind of car is it and what ecu?

don't flame me if i didn't see it


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## chimmike (Oct 17, 2002)

yeah I was wondering what car he's putting 550cc injectors in that has the stock ecu!


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## alex12582 (Sep 30, 2003)

I'm running a nissan/datsun 280zx turbo engine. Pic included.
All rebuilt, with 5000 miles on it. It's bored to 3.0 liter, ported and polished head and intake manifold, bigger ball-bearing turbo, HKS intercooler, dual bosch fuel pumps, 240sx throttle body, 3" exhaust system, K&N air filter, custom aluminum piping, Blow off valve, adjustable fuel pressure regulator, oil cooler, much more........
It's running OK. I'm running 14 psi boost and the engine is running lean under full throttle/boost. I need more fuel. I now have a custom made fuel rail which will be going on a car in a few days. 
I'm considering switching to a stand alone management system (TEC 3) as soon as the engine is run in. So I wanted to get the fuel injectors that can help me now with the stock ECU, and with TEC 3 later on. 
Hope this explains my situation.
Responses are appreciated.


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## jbanach77 (Jun 11, 2002)

i love the old school cars. very nicely done, i applaud it. i ran tech 2 on my 200sx. never had a fuel issue after that. you can run whatever injector you wnat with that stand alone. so 550cc's will be fine with that.


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## Taffy (Oct 30, 2003)

alex12582 said:


> Like the topic says.
> Thanks


As long as the injectors are high impedance, the ECU will be able to handle the injectors. You will need to change the program, via chip or other type of controller, to modify the pulse width.

Like the previous posts already pointed out, if you just plug in the 550 cc injectors, you will run rich.

From what I remember, the 280z used a top feed injector. I have not seen top feed injectors larger than 550cc that are still high impedance. If there are, please let me know. The side feed injectors that are used in later model Nissans can be had up to 850cc (maybe larger) in high impedance. We have some on our SR20DET powered 240sx.


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