Injectors, fuel pressure regulators, spark plugs, etc...

[2grimjim]

I finally have everything gathered up for a 4.6 build going into a 2006 LJ. One of the items I've spent untold hours was what injectors were available. Seems a lot of references here are older, and the various injector part numbers being recommended are either no longer available new, or becoming difficult to find reconditioned or used. On top of this, there's a lot of not-so-accurate info on the best sizing, the actual flow rates of the stock injectors, and posts describing frustration on trying to get things running right after a performance engine build. So, based on past engine build experiences and what I'd discovered lurking inside the ECU programming of the JTEC and NGC3 controllers, I've come up wit a "modernized" list of fuel injectors.

Two sources I've used that proved to be a wealth of knowledge were injectorplanet.com and injector-rehab.com

2004-2006 4.0 Jeeps are equipped with the NGC3 ECU. After downloading the stock programming with HP Tuners, I was able to validate that the stock program is assuming the injector flow rate is about 250 cc/min @4 bar (24 lbs/hr @ 58psi). Unfortunately the table for injector calibration doesn't have enough adjustability to enter flow rates for anything much larger than the stock size injector. Since the vast majority of injectors are flow rated at 3 bar, the stock NGC3 injector calibration has a 3 bar flow rate of 220 cc/min (21lb/hr). Now I had a starting point to "scale" the injector flow based on the projected power output. Another bit of knowledge with the stock NGC3 calibration is at max output, the stock 220 cc/min injectors are only operating at about a 65% duty cycle. So, If I scale the injector size based on an estimated 270 HP and a 65% duty cycle, I can find an injector that will require a minimal amount of adjustments on the VE tables and still guarantee that I have enough fuel delivery. At 270 hp, I have a scale factor of 1.5, meaning that I am producing 1.5 times the stock horsepower. 1.5 times the stock 220 cc injector size injector means that I need about 315 cc/min to meet my horsepower requirement and still stay close to the stock 65% duty cycle of the stock injectors. Right now, there's really only a handful of Bosch number options that have the correct USCAR connector and conical spray pattern. The best injector I've found for 250-280 hp is Bosch 0280158049 (Bosch catalog number 62648) for 2004-2006 NGC2 applications. It fits 2005-2007 Chevy/GM LS-2. This is a new technology, 4 hole, standard length EV14, high impedance injector. The "standard length" EV14 is 48mm long, shorter than the 60mm EV6, but Injector Rehab sells adapters for using the 48mm injectors in place of 60mm.

So, digging through the ECU programs for 1996-1998 JTEC, 1999-2003 JTEC+, and 2004-2006 NGC3 controllers, here's an updated list of injector choices:


Year/Make/Model/ECU Type/Connector Type Bosch Injector Catalog Numbers

240 hp 255 hp 270 hp 285 hp 300 hp
91-95 Jeep, all 4.0, Chrysler MPI, Jetronic 62385* Note 1 62687 Note 2 62203
96-98 Jeep, all 4.0, Chrysler JTEC, Jetronic Note 3 62687 Note 4 62203 Note 5
99-04 Jeep, all 4.0, Chrysler JTEC+, USCAR 62385** 62648 62648 62648 62647
05-06 Jeep, all 4.0, Chrysler NGC3, USCAR 62385** 62648 62648 62648 62647

Note 1, use 62385 or 62433, or Ford M-9593-LU24A with 3.7 bar (55 psi) fuel pressure. Must convert from Jetronic to USCAR connector
Note 2, use 62687 with fuel pressure at 3.5 bar (50 psi)
Note 3, use 62687 and modify ECU program to reduce fuel delivery
Note 4, use next lower power injector with modified ECU program to increase fuel as required
Note 5, use 62203 and modify ECU programming to increase fuel as required

*Ford M-9593-LU24A, or Bosch 62433 injectors may be substituted. Must use with 3.5 bar (50 psi) fuel pressure and convert from Jetronic to USCAR connectors
**M-9593-LU24A injectors are 24lb/hr @39.15psi (25.2 lb/hr @3 bar/43.5psi). Same as Bosch 0280158165 (62385), and 0280156081 (62433). May program ECU to add fuel as required.



Bosch Catalog Numbers:

62385 0-280-158-165 25.2lb/hr @43.5psi, 4 hole, conical spray pattern EV14CL Long, USCAR connector
GM/Mercury Marine/Volvo Penta 5.0L, 5.7L, 6.2L

62433 0-280-158-081 25.2lb/hr @43.5psi, 4 hole, conical spray pattern EV6CL Long, USCAR connector
GM/Mercury Marine/Volvo Penta 5.0L, 5.7L, 6.2L

62687 0-280-155-759 31.4lb/hr @43.5psi, 4 hole, conical spray pattern EV6CL Long, Jetronic connector
Volvo 2.3L B5234T, 2.5L B5254T

62203 0-280-155-868 34.6lb/hr @43.5psi, 4 hole, conical spray pattern EV6CL Long, Jetronic connector
GM 3.8L Supercharged

62648 0-280-158-049 29.4lb/hr @43.5psi, 4 hole, conical spray pattern EV14 Standard, USCAR connector
GM LS2 (requires NGI-2 SHORT extension from Injector Rehab)

62647 0-280-158-051 34.5lb/hr @43.5psi, 4 hole, conical spray pattern EV14CK Compact, USCAR connector
GM LS3/LS7/LS9/L76 (requires NGI-2 LONG extension from Injector Rehab)

More to follow...

[2grimjim]

I'll have to post a better table for the injector numbers.

[2grimjim]

Year/Make/Model/ECU Type/Connector Type, Bosch catalog number

91-95 Jeep, all 4.0, Chrysler MPI, Jetronic connector
240-255 hp, Bosch 62385, 62433, or Ford M-9593-LU24A w/ 55 psi (3.7 bar) fuel pressure (must convert to USCAR connector)
255-270 hp, Bosch 62385, 62433, or Ford M-9593-LU24A w/ 59 psi (4 bar) fuel pressure (must convert to USCAR connector)
270-285 hp, Bosch 62687 with 43.5 (3 bar) to 50 psi (3.5 bar) psi fuel pressure
285-300 hp, Bosch 62203 with 43.5 (3 bar) to 50 psi (3.5 bar) psi fuel pressure

96-98 Jeep, all 4.0, Chrysler JTEC, Jetronic connector
240-255 hp, Bosch 62385, 62433, or Ford M-9593-LU24A with modified fuel tables in ECU program, stock fuel pressure
(must convert to USCAR connector)
255-270 hp, Bosch 62687 with modified fuel tables in ECU program, stock fuel pressure (must convert to USCAR connector)
270-285 hp, Bosch 62687 or 62203 with modified fuel tables in ECU program, stock fuel pressure
285-300 hp, Bosch 62203 with modified fuel tables in ECU program, stock fuel pressure

99-04 Jeep, all 4.0, Chrysler JTEC+, USCAR connector
240-255 hp, Bosch 62385, 62433, or Ford M-9593-LU24A with modified fuel tables in ECU program, stock fuel pressure
255-270 hp, Bosch 62648 with modified fuel tables in ECU program, stock fuel pressure
270-285 hp, Bosch 62648 or 62647 with modified fuel tables in ECU program, stock fuel pressure (must use length adapter)
285-300 hp, Bosch 62647 with modified fuel tables in ECU program, stock fuel pressure (must use length adapter)

05-06 Jeep, all 4.0, Chrysler NGC3, USCAR connector
240-255 hp, Bosch 62385, 62433, or Ford M-9593-LU24A with modified fuel tables in ECU program, stock fuel pressure
255-270 hp, Bosch 62648 with modified fuel tables in ECU program, stock fuel pressure
270-285 hp, Bosch 62648 or 62647 with modified fuel tables in ECU program, stock fuel pressure (must use length adapter)
285-300 hp, Bosch 62647 with modified fuel tables in ECU program, stock fuel pressure (must use length adapter)

[2grimjim]

Pressure regulators:

Found elsewhere on this forum are part numbers for 91-95 fuel-rail, return system:

Standard Motor Products:
PR209, 55psi (3.7 bar)
PR210, 39psi (2.7 bar), Stock 91-95 Jeep 4.0
PR211, 50psi (3.5 bar), Various Dodge, Chrysler, Plymouth w/3.5L V-6, 1990-1997
PR321, 58psi (4 bar), Various Dodge, Chrysler, Plymouth w/3.8L V-6, 2000-2008


Regulators for 2004-2006 Jeep w/in-tank fuel pressure regulator:

Quantum Fuel Systems (www.highflowfuel.com)
PR-4, 58psi (4 bar), Stock fuel pressure
PR-9, 43.5psi (3 bar)
PR-42, 39psi (2.7 bar)
PR-435, 50psi (3.5bar)
PR-440, 59psi (4 bar)

Bosch
0280160575, 58psi (4 bar), Various Audi 1999-2003
0280160587, 55psi (3.7 bar), Various Mercedes Benz 1992-1993


No Information has been found for 1999-2003 Jeep fuel pressure regulators other than the stock replacement 49psi units.

The correct Walbro 255 LPH high flow fuel part number is GSS342BX. This should work in all 91-2006 Jeeps. You will need to buy the matching electrical connector from Amazon, Summit Racing, etc.
Quantum Fuel Systems (www.highflowfuel.com) also sells a Walbro 255 kit for Jeep.
Walbro is now TI Automotive, but their pumps haven't changes and are still high quality and made in USA.

[2grimjim]

The adapters for using LS2 injectors can be found here:
https://injector-rehab.com/product/14mm ... 2-to-48mm/

Adapters for using the LS3 injectors can be found here:
https://injector-rehab.com/product/14mm ... 2-adapter/

Conversion calculators (at bottom of page):
https://injector-rehab.com/knowledge-base/

[2grimjim]

Spark Plugs:

A bit of history on the odd, very long projected tip spark plugs used in the 4.0 and the 258. Early on in the history of both of these engines, they both used a normal looking "projected tip" spark plug where the insulator projects past the threaded shell by about 1.5 mm. Then, somewhere along the line (1991 for the 4.0, and 1978 for the 258), AMC and then Chrysler switched to a ridiculous 10+ mm extended tip. This was done for emissions reasons, nothing else. These long-nose become a huge liability as soon as you start making performance upgrades. The very long nose will cause detonation and pre-ignition because the ground electrode is much too long to be able to deal with the increased heat input from higher compression, bigger cams, etc. Throw these long nose spark plugs as far away as humanly possible.

For performance applications, you should always start with spark plugs that are at least one or more heat range numbers colder. On NGK, that would mean going from the stock 5 heat range to a 6 or 7. If there's a power adder involved (Nitrous, Turbo, Blower), go at least 2 or more heat range numbers colder. Not all spark plug manufacturers use larger numbers for colder plugs, Champion and Autolite use descending numbers for colder plugs.

My personal preference for spark plugs is NGK, ND (Nippondenso, or Denso), then Bosch. Motorcraft and AC/Delco are still OK due to the fact that that they are still OEM suppliers, but all others are junk. At the bottom of the barrel is Champion. In 40 years of wrenching, I've seen 3 sparkplugs blow the porcelain out while in service; all Champion. And all the gimmicky sparkplugs like E3 are also junk.

The NGK BKR6E and BKR6EIX are a good starting point. If you're running much over 10:1 compression, go with BKR7E or BKR7EIX. Power adders, go with BKR8 or 9. If you are running really high horsepower, a lot of nitrous, or a lot of boost, you need to go to a non-projected tip plug like NGK R series.

The only advantage of running the IX (or any other platinum, iridium, gold-palladium, ruthenium) is they last longer. Much, much, longer. Power adder or high compression applications are very hard on sparkplugs and the extra money for rare earth plugs is probably worth the money unless you like replacing spark plugs. In normal applications, the exotic metal sparkplugs will last 100,000 miles. Old-school "copper core" sparkplugs are usually pretty worn out at 25,000 miles.

I've seen a few here using or recommending the NGK ZFR6FIX-11. I would say stick with the BKR, for two reasons. The first is the ZFR series has a projected tip that is about 3 mm, twice as long as the BKR. The 2nd reason is the -11 suffix means the plug is pre-gapped to 1.1 mm (.044"). This is too much gap, especially if you are running higher compression or power adders. Bending the ground electrode to close up the gap only makes the edge of the ground electrode wear away faster and they will need replaced sooner.

For very high horsepower applications, you want to stay away from all projected or extended tip sparkplugs. The best for high horsepower applications is something similar to NGK R5671A-7, R5671A-8, R5671A-9, or R5671A-10. The dash number being the heat range. This type sparkplug will give maximum resistance to detonation and pre-ignition resulting from an overheated spark plug. But, these plugs will probably not work well if you have a mild engine build with the stock lean idle and cruise power ECU calibrations. Gap on these type plugs for high horsepower applications is usually between 0.025" and 0.032". Bigger gaps require big upgrades to the ignition like an MSD, matching coil, larger cap (to prevent cross-fire), and better quality sparkplug wires.

Spark plug gap is going to vary by application. Part of the reason the silly super long nose plug was adopted on the 4.0 in 1991 was the weak stock ignition system. The later coil-on-plug ignition used on 2000-2006 Jeeps is much more tolerant of bigger sparkplug gaps. Wider sparkplug gaps are necessary for consistent ignition of lean air-fuel mixtures. In the 1970's, vehicle manufacturers were forced to try to make engines run at leaner than what they had historically designed because of EPA emissions regulations. The 1970's was when you first saw high energy ignition systems to deal with wider sparkplug gaps. The wider gaps and higher energy ignition systems were necessary for a smooth idle and to prevent misfires from overly lean mixtures. On the 258 and 4.0, AMC, and later Chrysler, found it cheaper to go with an oddball sparkplug than redesign the ignition system for a more powerful spark. The OEM sparkplug gap has always been a rather conservative 0.035". High performance applications and the stock Jeep low power ignition will usually require that you keep at, or below the stock 0.035" gap. Go with bigger gap and not make any significant upgrades to the stock ignition system and you are guaranteed to experience full-load misfires. This is especially true on the 1999 and earlier Jeeps.

[2grimjim]

Ignition timing, compression, and exhaust:

The stock ECU calibrations on the JTEC, JTEC+, and NGC3 are really bad for performance applications. The light load timing tables are too aggressive to allow high compression to work with milder cams and still keep the fuel mixture ratios lean enough to allow for good fuel economy. And the full power timing is about 10° less than what you need for best power at a Lambda of 0.85. The full load timing with a stock iron head should be around 34° for a naturally aspirated gasoline build, and slightly less for the Edelbrock at 32°. The Edelbrock requiring less advance because of the better combustion chamber design. The stock ECU calibration is around 21° at full load. That's giving up a lot of torque (and horsepower).

Anyone that's had a 4.0 Jeep will tell you that they've experienced a little pinging using regular 85-87 octane fuel and mild loads. This is from the terrible long nose sparkplug and the overly aggressive timing mapping at medium loads. This bad timing calibration makes it a nightmare to get a stroker to run right, and most end up thinking it has to do with fuel injectors, fuel pressure, or the fuel pump. It's a viscous circle of frustration if your not doing any data logging with a wideband O2 sensor.

A good tune, injector, and sparkplug selection will allow a lot more compression than most DIY builders are using. But you aren't going to get there without some data logging and a wideband O2 meter.

If you have a 1991 to 1995 MPI ECU, you're pretty much in the cold for timing adjustment because there isn't anything you can do except try to modify the trigger windows on the flex plate for the CPS sensor.



An aluminum head will allow you at least a half point bump in the compression due to its ability to better manage combustion heat. Going to a 180° thermostat is going to help power also. Contrary to many myths, a colder thermostat will not wreak havoc on the engine or upset the ECU programming by running a colder thermostat. Altitude is going to have a big effect on how much compression you can ultimately run. Where I live, the elevation is 4,600 feet and you can run with 12.5:1 and an iron head all day long on 91 octane pump fuel. There's no reason, with a good tune, and good injector and sparkplug selection, you can't run 10.5-11:1 compression at sea level with an aluminum head, 180° thermostat and premium (92-93 octane) pump gas. The more compression, the better the power, and the better your fuel economy.



Exhaust systems downstream of the engine is something way too may people overlook. The stock Ø2.25" tail pipe is a power killer. Anything over 250 hp is going to require a Ø2.5" diameter exhaust minimum! for the full length of the vehicle. If you spent $7K on a Golden "270hp" engine, you're throwing away 20 hp by running an exhaust where there's anything smaller than Ø2.5" in the exhaust. Most single outlet headers have a Ø2.25" and just crush power above 250hp. The best header setup is the 2000-2006 dual outlet style. Even though the two outlets are only Ø1.75", they flow almost twice as much as the single Ø2.25" header outlet. Mufflers are another power robber if they are a bad design. I hate the traditional Flowmaster muffler. They're annoyingly loud and don't flow any better than most baffle type mufflers. For my Jeep, I'm running a full Ø2.5" exhaust system with two small straight though mufflers, one slightly longer than the other. It's very quiet and runs much better than any other muffler setup I've used.

[2grimjim]

EV1 vs EV6 vs EV14 injectors:

There seems to be a lot of confusion and misinformation about the differences between these classifications of injectors. The EV reference really has nothing to do with the connector type, impedance, or size/shape of the injector. The EV designation is just the evolution of the technology of these injector. Each EV class is available in multiple connector styles, spray patterns, and impedance values. So, they will generally interchange with each other provided you use the same connector type and impedance class. I'll try to break it down into the most relevant features.



Connectors:

There are four common electrical connector types; D-Jetronic, L-Jetronic, Sumitomo, and USCAR. There are a few manufacturer specific connector types that are not common.

D-Jetronic connectors were used on the very early Bosch FI systems beginning in 1968. This was used up through the late 1970's, but largely abandoned by 1980. D-Jetonic connectors were replaced by L-Jetronic connectors. The L-Jetronic connector is the most prolific connector type and still very common today. As Japanese manufacturers adopted Bosch type injection systems in the 1980's, they standardized their own connector type that still seen on Asian automobiles today. This is called the Sumitomo connector. Beginning in the late 1990's, a fourth connector became common among North American auto manufacturers. This is the USCAR connector, commonly found on most GM, Ford, and Chrysler vehicles manufactured after 1999.

The EV1 technology class injectors are easily identifies as the "fat body" injector. These were the first generation injectors from the late 1960's up to the late 1990's. Early EV-1 injectors used the D-Jetronic connector through the 1970's, and later EV-1 up to the late 1990's used the L-Jetronic and Sumitomo connector. I'm not aware of any EV-1 class injector that uses a USCAR connector.

EV-6 technology class injectors were the replacement for the EV-1. These started to appeared in the mid 1990's. EV-6 injectors are available with L-Jetronic (simply called Jetronic today), Sumitomo, and USCAR connectors. No EV-6 class injectors are made with the old D-Jetronic connector.

EV-14 (and EV-12) are the newest technology and was a quick follow up as an improved EV-6. These started showing up in the late 1990's. The EV-14 also uses the Jetronic, Sumitomo, and USCAR connectors. No EV-14 class injectors are made with the old D-Jetronic connector.

1987-1998 Jeeps use the L-Jetronic (Jetronic) connector. All Jeeps from 1999-2006 use the USCAR connector. You can change the connector on the wiring harness or buy adapter plugs if you want to use injectors with a connector that doesn't match your wiring harness. Makes no difference in how the EFI functions. Just make sure you get the polarity of the wires/pins correct!



Length:

Beginning with the EV-6, you will start to see injectors with different lengths. The EV-6 was most commonly found as a 60 mm long injector, approximately the same length as the EV-1. The 60 mm EV-6 is by far the most common. The EV-14 comes in 4 different common lengths: 60 mm (called EV-14 long), 48 mm (EV-14 Standard), 38 mm (EV-14 Compact), and a very short one called a Pico.

Adapters for using the different lengths can be found from multiple sources.



Spray pattern:

Over the years, there have been many spray patterns used with injectors using anywhere from one to 12 holes. EV-1 were almost all single hole injectors with a few oddballs that used 2 holes that had two separate flow streams at various angles. EV-6 and EV-14 have many spray pattern types. As far as any injector spray pattern needed for a Jeep engine build, there's only two types that are desirable. The single hole and the conical spray pattern 4 hole. Not all 4 hole injectors spray a uniform conical pattern!. There are many 4 hole injectors that spray a "V pattern" with two distinct streams of fuel. These are commonly found on injectors used in applications where there's 2 intake valves supplied by a single injector. A good example would 2004 and later Ford 4.6L and 5.4L modular V-8's with the three valve cylinder head.

A good reference to find out the spray pattern, flow rates, or connector types is Injector Planet https://www.injectorplanet.com/



Impedance:

Early EV-1 injectors were mostly Low Impedance designs. Impedance is just another term used for electrical resistance. Low impedance injectors are generally defined as less than 10 ohms resistance. Most Low Impedance injectors measure between 2 and 5 ohms. Later EV-1, and as far as I've seen all EV-6 and EV-14, are classified as High Impedance injectors. Most High Impedance injectors measure between 12-16 ohms.

Low Impedance and High Impedance injectors are NOT interchangeable! You must use the impedance class your ECU was designed to use. All Jeeps from 1991-2006 use High Impedance injectors.



Summary:

The EV-14 is the best technology injector to use. The advancement in technology comes from the faster reaction times of the armature that opens and closes the injector. This allows you to size your injector up and keep the duty cycle low but still get good fuel control at idle.

Size your injectors to match your horsepower and keep the duty cycle below 80% at max power.

[2grimjim]

A correction on a previous post:

The Chrysler NGC3 controller (or Powertrain Control Module, PCM) was only used on 2005-2006 Jeep Wranglers. Not 2004.
The NGC3 has 4 connectors and incorporates transmission control for the 42RLE in the same box as the engine control.

The JTEC+ ECM was used on 2000-2004 Wranglers and Grand Cherokees (WJ), and 2000-2001 Cherokee (XJ) 4.0.
The JTEC+ uses a separate transmission control module for the Aisin Warner AW4 (2000-2001 Cherokee 4.0), Chrysler 42RE (2000-2004 Grand Cherokee 4.0), or the Chrysler 42RLE (late 2003-2004 Wrangler 4.0)

The JTEC ECM was used on 1996-1999 Wrangler, Cherokee (XJ) and Grand Cherokee (ZJ and WJ).
The JTEC+ uses a separate transmission control module for the Aisin Warner AW4 (1996-1999 Cherokee 4.0), Chrysler 42RE (1996-1998 Grand Cherokee ZJ 4.0, and 1999 Grand Cherokee WJ 4.0).

The difference between the JTEC and JTEC+ was the change from a distributor to coil-on-plug ignition. The JTEC and JTEC+ both use 3 connectors on the ECM, where the NGC3 uses 4.

All three of these controllers are supported by HP Tuners and can have the fuel and timing maps modified by the user by re-flashing through the OBD2 connector.

The 1991 to 1995 Chysler MPI is OBD1 and does not use flash memory. Therefore, these Chrysler MPI controllers are not re-programmable. Same for the old 1987-1990 Renix FI controller.