Bought a 1990 YJ about 2 months ago...
Dana 30 Front
Dana 35 Rear w/ SSBC Disc Brake Conversion
IPF Headlight Conversion
Tuffy Center Console
Wilderness Rack Rear Swingout
Tan Bestop Softtop
This weekend will be doing a 4.0L Fuel Injection Swap. Will be placing a 4.0L head, intake, and wiring harness on a 4.2L. The reason for doing this is to keep the low end torque of the 4.2 and combine it with the high end output of the 4.0L, also will increase gas mileage about a 100+ a tank and add 65HP, you will gain 40HP by just swaping out the heads and keeping your carb setup, and an extra 25HP to 30HP by going to fuel injection. The reason for a 40HP jump in heads alone is due to the angle and cut of the intake and exhaust ports, and air flow inside the head, will give the air fuel mixture smoother lines to pass through and better atomize the air fuel mixture. This swap is pretty straight forward and I will try to do my best to cover everything, unlike articles I have read in the past. This will be my 5th swap, including a 2.5L to 4.0L in a Rio Grande. The wiring is straight forward, but there are some things to know. An OBD 1 (91-95) ECM is the easiest to install, and will only require 5 wires to run your vehicle. 2.5 and 4.0 ECMs differ, so if you are doing a swap from a 2.5 you will need to pick up a 4.0 ECM, I know they look the same but your 4.0 has 2 more cylinders to account for. Also if you install swap a 4.0 for a 2.5, you will need to cut grind and re-weld your motor mounts on the frame 4 inches towards the front. You will also have to add 4 wires for the 2 new injectors, 2 grounds and 2 hots. ECM always grounds, every wire on the ECM with the exception of 3 get grounded at the ECM, that's how the system works. The PDC (Power Distribution Center) gives power to everything in the system. With the 4.2 Fuel Injection, you will need to cap off the water jackets closest to the intake manifold, I will include pictures when I do this. I know I haven't covered everything yet, but we will get there. If I have already completed this swap just keep reading, I will also include bulkhead pinouts and wiring diagrams from the FSM (Factory Shop Manual) for YJs. As far as the fuel pump issue goes, you will need to purchase a fuel pump for a 1991 and later YJ, and if you already have a 2.5, you do not need to swap the pumps out, they are the same output. You just drop the tank and removing the hanger and sending unit, and Advance Auto sells the whole assembly for $131, it just drops right in, all you have to do is connect one wire, and I will cover that later when we reach that point. Any questions, please ask...
Several Key Notes Before I Begin this swap, for people interested the best of each in my opinion is in bold lettering
3 Types of Computer Systems
Renix - Very Bad System, Came on 87-90 Jeep Cherokee 4.0L
OBD1- Best For Swaps, Came on 91-95 Cherokee's, Wranglers, Commanches, and Grand Cherokee's
OBD2- Good System, Harder for swaps, Came on 96-01 Cherokee, 97-05 Wrangler, and Grand Cherokee's
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, ...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
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 19.2lb/hr @ 44.1psi (ACC-150119)
Accel 21.1lb/hr @ 44.1psi (ACC-150121)
Accel 24.4lb/hr @ 44.1psi (ACC-150124)
Accel 25.6lb/hr @ 44.1psi (ACC-150126)
Accel 29.4lb/hr @ 44.1psi (ACC-150130)
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)
The stock cylinder head is cast iron and weighs 60lb. The valve head diameter is 1.91" intake/1.50" exhaust. Casting numbers are as follows:
Cylinder head flow figures (cfm) at 28inH2O pressure drop are:
Non-HO head #2686 (Courtesy of Greg Friedman)
Valve lift (in)..... 0.2 ... 0.3 ... 0.4 ... 0.5 ... 0.6
Intake flow.... 122.0 168.0 186.0 189.0 192.0
Exhaust flow....88.0 114.0 130.0 134.0 138.0
Ported non-HO head #2686
Valve lift (in)..... 0.2 ... 0.3 ... 0.4 ... 0.5 ... 0.6
Intake flow.... 124.0 183.0 197.0 207.0 216.0
Exhaust flow....87.0 113.0 138.0 153.0 159.0
HO head #7120 & #0630 (Courtesy of John Brown)
Valve lift (in)... 0.1 ... 0.2 ... 0.3 ... 0.4 ... 0.5 ... 0.6
Intake flow.... 66.0 128.0 179.0 206.0 209.0 209.0
Exhaust flow. 55.0 100.0 120.0 136.0 141.0 141.2
HO head #0331
Valve lift (in)..... 0.1 ... 0.2 ... 0.3 ... 0.4 ... 0.5 ... 0.6
Intake flow..... 59.4 122.6 171.1 201.1 214.3 218.4
Exhaust flow...47.1 93.4 123.3 140.9 147.0 149.7
Ported big valve 2.02/1.60 HO head
Valve lift (in)... 0.1 ... 0.2 ... 0.3 ... 0.4 ... 0.5
Intake flow.... 73.9 142.4 197.8 229.8 247.0
Exhaust flow. 65.3 114.0 135.9 146.3 157.1
The early '87-'90 non-HO heads have low intake ports that flow rather poorly
. The later HO heads have higher intake ports that flow more air by allowing a straighter shot into the cylinders.
The '91-'95 HO heads with casting no.7120 have the highest intake and exhaust port airflows, especially at lower valve lifts where it is most important, and are the best for performance. The '96-'99 0630 heads are almost identical except that they don't have a port for the coolant temp. gauge sending unit. The '00 and later HO heads with casting no.0331 have smaller exhaust ports to produce a faster warm-up of the catalytic converter and improve emissions, but performance also suffers because the ports don't flow as well as those of the 7120 and 0630 castings.
The exhaust ports flow relatively poorly compared to the intake ports on all the 4.0 heads so this engine would perform better with a dual pattern cam that has more exhaust valve opening duration and lift than the intake.
The intake ports of the HO head are rectangular and measure 1.625" x 1.375", while the exhaust ports are elliptical and measure only 1.375" x 1.250". The port cross-sectional areas are 2.234 and 1.350 sq. inches respectively. For good street performance, it is recommended that the port c/s area should be about 85% of the valve head area. Therefore it should be 2.435 sq. in. for the intake ports and 1.502 sq. in. for the exhaust ports. The stock port c/s areas therefore need to be enlarged by 9.0% for the intake and 11.3% for the exhaust. The ports should be matched to the intake and exhaust manifold runners to smoothen airflow and prevent power-robbing turbulence.
For those who would like to undertake a DIY head porting job, the Standard Abrasives DIY Head Porting Guide
is a must read.
The compressed thicknesses of the following gaskets for the 4.0 engine are:
Stock 4.0 (all years) 53020754AB----0.051"
Mopar Performance P4529242 / Victor Reinz Dana 5713----0.043"
Corteco 20667CS '87-'95, Corteco 20871 '96-'06 ----0.051"
The pin heights and dish volumes of pistons available for the 4.0 engine are:
Stock 4.0 cast aluminium '87-'93 #83500251, '94-'95 #4773157, '96-'06 #4798329----1.601" 13.1cc
Keith-Black Silvolite (UEM) cast aluminium 2229/2229c----1.581" 11.5cc
Keith-Black Silvolite (UEM) hypereutectic 3241hc/3242hc----1.592" 13.3cc
Sealed Power (Sterling) cast aluminium 677P/677CP----1.585" 17.5cc
Sealed Power (Sterling) hypereutectic H802CP/H825CP----1.592" 15.1cc
Keith-Black Silvolite (UEM) forged stroker IC944----1.353" 21.0cc NEW
Keith-Black Silvolite (UEM) forged stroker IC945----1.353" 10.8cc NEW
The '91-'99 intake manifold is aluminium and has equal length 24cm (9.5") long runners. The runners are rectangular with internal dimensions of 1.625" x 1.375" and a cross sectional area of 2.234 sq. in. (14.4 sq. cm). The '00-'06 intake manifold has smaller diameter curved runners with internal dimensions of 1.53" x 1.26" and a cross sectional area of 1.928 sq. in. (12.4 sq. cm), and is clearly designed to produce more torque at lower rpm. The distance from the intake valve to the port opening is 3.5" (9cm), making the total distance 13" (33cm) from the manifold plenum wall to the intake valve.
For a given intake manifold design, the cross-sectional area of the runner and the runner length affect the location of an engine's torque peak in the RPM band. According to the Helmholtz tuning model and the formula shown here
, the intake runner area and length are tuned to resonate and produce an inertial supercharging effect at 5000rpm for the '91-'99 engine and 4650rpm for the '00-'06 engine. That's very close to peak horsepower rpm for all High Output 4.0L engines.
The same design principles for the intake manifold also apply to the exhaust manifold. The cross-sectional area of the primary header pipe affects the location of an engine's torque peak in the RPM band. The pipe length generally will not change the peak torque or the RPM at which it occurs. A length change has the effect of improving the torque on only one side of the peak by "borrowing" it from the other side. A shorter pipe improves torque after the peak (reduces it at lower RPM), preventing the torque curve from falling off so quickly as speed increases. A longer pipe extends the torque curve backwards to improve the engine's flexibility, at the expense of after-peak torque.
The stock exhaust manifold and the Borla header have a primary pipe internal diameter of 1.375" and a cross sectional area of 1.49 sq. in. Using this formula:
Peak Torque RPM = [Primary Pipe Area (sq. in) X 88200] / Cylinder Volume (cu. in.)
the stock exhaust manifold and the Borla header are tuned to a peak torque of 3265rpm. That's right at the peak torque rpm of the 4.0 engine.
Block Casting Numbers
Year............Casting No. ...........................Part No.
Crankshaft Casting Numbers
The stock Jeep 4.0 crankshaft is nodular iron, has 8 counterweights, and weighs 55lb.
Year............Casting No.........Part No.
Connecting Rod Casting Numbers
Stock Jeep 4.0 rods are cast iron, 6.125" long from center to center, and weigh 660g. The casting no. is 53020126 for all years.
Stock pushrods are oil-through type with pressed-in balls at each end. They are 5/16" in diameter and 9.625" long
The 5-speed manual transmission is the light-duty Peugeot BA10/5 in the '87-'89.5 4.0 XJ, the medium duty Aisin-Warner AX15 in the '89.5-'99 4.0 XJ, and the medium-duty New Venture Gear NVG3550 in the '00-'01 4.0 XJ. When carrying out engine swaps (either another 4.0 or a stroker), selection of the correct pilot bearing can be a headache. The details below will make choosing a pilot bearing simple:
OEM pilot bearing 33004041 for '87-'91 4.0 engine
Advance Adapters pilot bushing 716120 for '92-'06 4.0 engine
*Upgrade transmission to AX15 or NVG3550 for stroker engine swap*
OEM pilot bearing 33004041 for '87-'91 4.0 engine or stroker
Advance Adapters pilot bushing 716120 for '92-'06 4.0 engine
'92-'99 AX15 and NVG3550:
OEM pilot bearing 53009180AB for '87-'91 engine or stroker
OEM pilot bearing 53009180AB or 53009181 for '92-'06 4.0 engine.
If you are swaping out your 4.2 to a 4.0 or converting the 4.2 you have to fuel injection, you will need to adapt 3 very key things... You cannot just simply put the new motor in and plug up the 4.0L Bulkhead connector and expect it to run.
CPS (Crankshaft Position Sensor) - If you have the AX-15 Transmission, there will be a cuttout in the transmission for the sensor, you will just have to find or buy one and put it in:::You will also have to replace the flywheel with a 91-95 in order to use the fuel injection. If you have the BA-10 5 Speed, the TF-999 Automatic or another type of transmission other than a Jeep, you will have to buy the Hesco Kit to relocate this sensor to the Harmonic Balancer. http://www.hesco.us/products/7902/40...1-04-hes9199ed
Vehicle Speed Sensor - This is located on the backside of your transfer case and has your speedometer attached. The one you need for fuel injection looks the exact same except has an additional electrical connection that tells the ECM how fast your going which controls fuel curve. Hesco makes this also, http://www.hesco.us/products/7902/40...sensor-hes7015 . You can also buy one for a 91 YJ at the parts store that will have both connections as well, however you will have to do some modifications for it to work. I suggest using the Hesco Part.
Neautral Safety Switch (NSS) - This tells the ECM that your in Park or Neautral and it's safe to start the vehicle. You can fool this by putting a female wire connector on pins B and C to connect them to each other, completing the circuit. The connector is large and black and found on the passenger side of the motors main wiring harness for the 4.0L.
Please DO not post things you think I should do or something that I have not covered because it will only confuse people that are interested in swaps. I promise to cover everything in due time... just stay tuned and crawl this thread, doesn't matter if your an experienced jeeper, or new trying to better your knowledge and your rig... you will learn something from this thread I promise.
THIS IS AN UPDATE::::
Fuel Injection Wiring seems to be the thing that I get call about the most, second would be why is my Jeep not starting. I hope to clear up a few things with this update.
The easiest way to do this swap is to leave your 4.2L Engine Harness alone... all of it. I suggest to lay the 4.0L Harness right on top of it. If you do this it makes life a lot easier.
If the harness is left alone, you will only need to provide power to the ECM, Fuel Pump and Ignition. Doing this, your jeep will run. Also put the Oil Pressure Sending Unit and the Water Temp Sending Unit from the 4.2L on the new motor. Doing this and running the electrical connections off of your 4.2L harness will ensure that you have accurate working gauges when your done.
Also, I strongly suggest putting in a Check Engine Light when doing your swap. If something does not work, it will tell you by doing a simple test. Everything about all of this is covered in this thread and easily found. These are just key notes after years of phone calls and frustrations from Jeepers in need of help.
I do not mind helping anyone, you may PM or Call me. However do remember that I am helping you fix your Jeep when I answer those PM's and phone calls. I take time away from my family, friends and work sometimes to help out. I do not ask for anything in return, other than a donation of your choice to my paypal account for my time.
DO NOT UNDER ANY CIRCUMSTANCE, CALL ME IF YOU ARE WORKING ON A CUSTOMERS JEEP THAT YOU CANNOT FIX, UNLESS YOU PLAN ON PAYING ME UPFRONT FOR MY TIME. IT GRINDS MY GEARS WHEN I AM TAKING TIME AWAY FROM MY FAMILY TO HELP SOMEONE ONLY TO FIND OUT AT SOME POINT THAT IT'S A CUSTOMERS JEEP THAT THEY CAN'T SEEM TO GET RUNNING RIGHT DURING A SWAP. IF YOU DO CALL BECAUSE YOU NEED HELP THAT BADLY, BE PREPARED TO PAY FOR MY TIME AND SERVICE. I WILL WARN YOU HOWEVER, THAT I AM NOT CHEAP.
Here is a few pictures...