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H.O. fuel injectors...Does any non-OEM fuel injector put out 21lbs at 39 psi?

92DripCherokee

NAXJA Forum User
Location
Tampa, Florida
Does any non-OEM fuel injector put out 21lbs at 39 psi?

The OEM 21lb Siemens injectors are ideal and too expensive, a well known fact. Why spend $400 for another 1-2 mpg?

At 39 psi, a #19 would run lean, and a #24 would run rich.

My 1992 HO engine is bored out .030, APN header, 2.5 inch exhaust and a cone filter etc, nothing fancy. Doesnt need extra fuel, theres no extra displacement.
(The Renix engines once again are shown to be more straightforward beasts, the #19 ford injectors are near perfect matches for OEM)
 
isnt 39psi low for the HO engine?

i thought the renix puts out 39psi and the HO was 49psi.

how about looking into an adjustable fuel regulator?
 
Well, there are two kinds of HO fuel system. Early HO has a fuel rail mounted regulator with a return line, the late HO uses an in-tank regulator and is "returnless".


Model Year, ...Part #, ......Colour, .....Fuel Pressure, ...Static Flow,
'87-'90, ........53003956, ...Black, ........39psi, .................18.6lb/hr
'91-'93, ........33007127, ...Brown, .......39psi, .................21.0lb/hr
'94-'95, ........53030343, ...Tan, ...........39psi, .................21.0lb/hr
'96-'99, ........53030778, ...Grey, .........49psi, .................23.2lb/hr
'00-'01, ........04854181, ...Blue tip, .....49psi, .................22.5lb/hr

91-95 run at 39 psi

An adjustable FP regulator will only limit the maximum pressure at lower RPM. I don't think it would let me run injectors from the "high pressure" HO.

Looks like virtually everyone who changes injectors is either Renix, or a stroker motor. Still searching...
 
didnt someone in the last week or 2 put chevy LT1 injectors in his 96?

try a search for chevy injectors
 
I would look for a set of ford 24 lb/hr injectors on e-bay. It will not make you run rich as the computer will adjust pulse width to maintain mixture. I got a set of stock 5.0 injectors on e-bay for $20 and have been very happy with them.
 
I just swapped in some injectors from a 94 Crown Vic. It had the 4.6L in it. The Jeep isn't registered right now so I have no mileage data, but the idle is alot smoother & throttle response is better. JIM.
 
jeeperjohn said:
I would look for a set of ford 24 lb/hr injectors on e-bay. It will not make you run rich as the computer will adjust pulse width to maintain mixture. I got a set of stock 5.0 injectors on e-bay for $20 and have been very happy with them.

Not quite all true. It will while using less that 80% throttle and coolant is above 175*C. Below that temperature and above 80% throttle the O2 sensor is not read as the ECU goes into open loop mode. So having larger injectors will cause more fuel to be used. The answer then is to tune it for those conditions with an adjustable MAP sensor: http://www.go.jeep-xj.info/HowtoMAPsensor.htm
 
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I wish I could just find a simple answer for which injectors to swap into my 2000 XJ....cant ever get a straight answer!!! :)
 
I'd like an upgraded one though....something with multiple nozzles on the injector....heard thats better for atomization.
 
Gojeep said:
Not quite all true. It will while using less that 80% throttle and coolant is above 175*C. Below that temperature and above 80% throttle the O2 sensor is not read as the ECU goes into open loop mode. So having larger injectors will cause more fuel to be used. The answer then is to tune it for those conditions with an adjustable MAP sensor: http://www.go.jeep-xj.info/HowtoMAPsensor.htm

Isnt the ECU in open loop mode upon startup anyway? regardless of injector size...til your engine reaches normal operating temp, its considered open loop and your O2 sensors basically have no input (probably why you get shitty gas mileage if you run a 160 degree thermostat).

and 80% throttle? who goes up that high? I dont rev my engine up like that ever...4400RPM or higher?
 
Gojeep said:
Not quite all true. It will while using less that 80% throttle and coolant is above 175*C. Below that temperature and above 80% throttle the O2 sensor is not read as the ECU goes into open loop mode. So having larger injectors will cause more fuel to be used. The answer then is to tune it for those conditions with an adjustable MAP sensor: http://www.go.jeep-xj.info/HowtoMAPsensor.htm
Thanks Gojeep, I wasn't considering open loop mode.
 
JNickel101 said:
Isnt the ECU in open loop mode upon startup anyway? regardless of injector size...til your engine reaches normal operating temp, its considered open loop and your O2 sensors basically have no input (probably why you get shitty gas mileage if you run a 160 degree thermostat).

and 80% throttle? who goes up that high? I dont rev my engine up like that ever...4400RPM or higher?

That is what I said when I stated that it is only in closed loop above 175*F. That is the same as saying it is in open loop below 175*F.
 
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