how to go from 10 to 17mpg (city) with RENIX

Just an update on my old RENIX:

Car has been using lots of fuel ever since I got it. Barely making 10 miles/gallon (city driving that is).. After extensive troubleshooting+replacing all sensors+inspecting cylinders and replacing piston rings, my wits were at an end... Even the spark plugs had a nice tan hue, indicating a healty mixture ration... What was I to do???

As a last resort, I though I might try to swap my fuel injectors for more modern Ford 19# yellow-tops, but did not dare to hope for any significant improvement... boy, was I in for a surprise...

My mpg instantly leapt from a lousy 10 (city) to about 16-17!!!!!! Just by replacing my old injectors, which had shown no symptoms of malfunction... I'm VERY happy with this, as I'm running 5" lift, 32"x11,5" tires, and stock axle ratios...

Beside the good milage I really can't tell much difference from the old injectors. Just that I don't have to push the accelerator as far in as before, and perhaps a somewhat smoother running operation...

And the best thing. I found the Ford injectors (8pcs) on e-bay for about 50$... new and with o-rings included...



Rejoyce! recjoyce! it's a new era! party1:

They could have been clogged. And the Ford injectors have 5 holes for spraying fuel, so the atomization is better and helps the fuel burn better.

Johnnie Walker said:

They could have been clogged. And the Ford injectors have 5 holes for spraying fuel, so the atomization is better and helps the fuel burn better.

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Four holes. :eeks1: Unless they have changed again?

wow thats quite impressive, hows the power compared to the old injectors

Ford #19 came in what engine?......SANTA

+1, Id like to know this myself.

Power is about the same. Possibly some more torque on low revs.

4 holes.

Ford #19 (aka yellow tops) delivered in many mid-90s fords, like mustang etc. Do an e-bay search for "ford #19 injectors" og "ford 19 lbs injectors" or "ford injector yellow"... They are used in lots of Fords... (they are the ones that have a yellow top half and black bottom half)

I liitle off topic....but does anyone know if a upgrade fuel injector for a 2000 XJ, 4.0 w/AW4? Been getting crappy around town milage as well and it is most likely the injectors.

willam said:

I liitle off topic....but does anyone know if a upgrade fuel injector for a 2000 XJ, 4.0 w/AW4? Been getting crappy around town milage as well and it is most likely the injectors.

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x2

Cool beans! would this work on a 91 cherokee? woud like to benefit from better gas milage. my rig has more than 200xxx miles.

THANKS!

willam said:

I liitle off topic....but does anyone know if a upgrade fuel injector for a 2000 XJ, 4.0 w/AW4? Been getting crappy around town milage as well and it is most likely the injectors.

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Run a 20 oz bottle of Chevron Techron FUEL SYSTEM CLEANER not Fuel Injector cleaner, thru a 3/4 tank of gas. The fuel system cleaner has a higher concentration of cleaners than the fuel injector cleaner. It has proven pretty good on my jeeps, TJ's, ZJ and XJ.

4xSanta said:

Ford #19 came in what engine?......SANTA

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The Ford (Bosch) orange-top 19 lb. injectors are used in 3.8 L and up engines, in cars, pickups, and vans even up to the F350.

Note: I know that the orange-tops work great in Renix jeeps, but I don't know about 1991 and up. The rating increased on the later XJs, but there are other Ford injectors with higher ratings, so as long as the connector and length are right you should find something that fits.

Here is the color code:

Injector Lb Ford Color
14 Lb/Hr Gray
19 Lb/Hr Orange
24 Lb/Hr Lt Blue
30 Lb/Hr Red
36 Lb/Hr Dk Blue
42 Lb/Hr Lt Green

some injector info cut and paste from another thread

Injectors *********

The following is a list of the injectors used on the 4.0L since 1987 along with their rated static flow:

Model Year, ...Part #, ......Colour, .....Fuel Pressure, ...Static Flow,
'87-'90, ........53003956, ...Dark Tan, ...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
'99-'01, ........04854181, ...Blue tip, .....49psi, .................22.5lb/hr

The injector flow rate varies as the square root of the pressure drop across the injector. The stock '91-'95 4.0 injectors are rated at 22lb/hr @ 43psi fuel pressure, so at 39psi they flow ( sq. rt.(39/43) x 22.0 = 21.0 ).

For stock/modified 4.0 engines or stroker build-ups the following injectors can be installed. The flow rates are:

Ford Motorsport 19.0lb/hr @ 39psi (Part no. FMS-M9593-C302)
Ford Motorsport 24.0lb/hr @ 39psi (Part no. FMS-M9593-A302)
Ford Motorsport 30.0lb/hr @ 39psi (Part no. FMS-M9593-B302)
Chevy LT1 24.0lb/hr @ 43.5psi (Part no. 17124248)
Chevy LT4 28.0lb/hr @ 43.5psi (Part no. 17124251)
'98 Chevy LS1 25.2lb/hr @ 58.0psi (Part no. 12533952)
'99-'00 Chevy LS1 26.2lb/hr @ 58.0psi (Part no. 12456154)
'01-'02 Chevy LS1/LS6 28.6lb/hr @ 58.0psi (Part no. 12482704)
Accel 19lb/hr @ 43.5psi (ACC-150819)
Accel 24lb/hr @ 43.5psi (ACC-150824)
Accel 26lb/hr @ 43.5psi (ACC-150826)
Accel 30lb/hr @ 43.5psi (ACC-150830)

The '95 Jeep 5.2 ZJ/Dodge 5.9 injectors (Part no. 53030262) are rated to flow 24.6lb/hr at 39psi.

The selection of injector size will depend on the estimated horsepower output, brake specific fuel consumption BSFC (assume 0.5), no. of cylinders, and the injector duty cycle (assume 80% or 0.8). The formula is:

Injector size (lb/hr) = (horsepower x 0.5)/(no.of cylinders x 0.8)

these?

joe_peters said:

Four holes. :eeks1: Unless they have changed again?

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My mistake, but they do have more than the stock injectors.

RichP said:

Run a 20 oz bottle of Chevron Techron FUEL SYSTEM CLEANER not Fuel Injector cleaner, thru a 3/4 tank of gas. The fuel system cleaner has a higher concentration of cleaners than the fuel injector cleaner. It has proven pretty good on my jeeps, TJ's, ZJ and XJ.

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Seafoam will work the same, you do not actually need as much either. You can also run it thru your intake ( I usually use the brake booster hose) and the crankcase.

ive been thinking about the Seafoam, just scares me. kinda like if it aint broke don't fix it. i feel like it might loosen up some stuff internaly and make things worse then i was before.

I use the LUCAS Fuel Injector Cleaner and Upper Cylinder Lubricant every other tank full, I usually see about a 2-3 mpg improvement on the tank-fulls that I run it. The RENIX XJ seems to love it better than the HO's do. I have all new BOSCH OE replacement injectors on my RENIX and they do very good.

SeansXJ said:

ive been thinking about the Seafoam, just scares me. kinda like if it aint broke don't fix it. i feel like it might loosen up some stuff internaly and make things worse then i was before.

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I've used it on most of my vehicles. Even my old XJ that had 350k on it. Only major thing to ever go wrong with it was the water pump. Just run 1/3 thru your intake, 1/3 in your fuel and the last of it in your crankcase (for crankcase - 500 miles or less before your next oil change.

Just to clarify, running Seafoam thru your intake will not clean your injectors, but clean your combustion chambers (since the topic seems to be injectors). I too prefer to use straight Techron to clean the injectors as well as the combustion chambers.

SeansXJ said:

these?

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Yes, these have the right look! And the Ford O-rings are WAY easier to install than the Jeep ones, but still gives a good seal.