PL2k Neon Engine Information

2002.1 Single Overhead Cam (SOHC)

The second generation 2.0 litre SOHC (still designated ECB) engine is standard in most U.S. spec Neons. It is not available in the ACR or the R/T. The basic design is the same as the first generation, and shares all the internals with the original engine. The mounting system was redesigned to improve durability and NVH isolation, and the accessories were changed to a serpentine drive configuration. Relocating the airbox to the left front corner of the engine compartment shortened the path and reduced the intake air temperature. The intake manifold was retuned to provide slightly more torque with a peak lower in the power band.

Due to the various reconfigurations, very few of the external bolt-ons from the first generation fit the newer car; however, most items are now available in PL2k versions. Stretching the definition of "bolt-on", the SOHC camshafts are interchangeable between engines. This means that second generation cars can use the '95-spec SOHC cam (with stock valve springs) or take advantage of the Magnum camshaft (with the Magnum-specific valve springs) for added power. Aftermarket SOHC cams will also work in both engines.

2003+ 2.0 litre SOHC motors received lower compression to reduce noxious emmissions. I assume this was achieved with a new piston assembly, as the part number is different for 2003+.

PL2k SOHC Engine Specs
Year 2000-2002 2003-?
HP Peak: 132 hp @ 5600 rpm 132 hp @ 5600 rpm
Torque Peak: 130 ft/lb @ 4600 rpm 130 ft/lb @ 4600 rpm
Redline: 6500 rpm 6500 rpm
Rev Limiter: 6750 rpm 6750 rpm
Compression: 9.8 to 1 9.3 to 1
Bore x Stroke: 3.44 in x 3.27 in 3.44 in x 3.27 in
Recommended Gas: 87 octane 87 octane

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2002.2 Magnum Single Overhead Cam (SOHC)

The 2.0 litre Magnum SOHC (designated ECH) engine is standard in the ACR and the R/T. This engine is fundamentally the same as the base SOHC. Additional power comes from a more aggressive cam grind and a trick two stage intake manifold. Like a four-barrel carburetor of old, the Magnum intake manifold has primary runners (open all the time) and secondary runners that open and close to add additional air volume when needed. The Magnum head also contains larger exhaust ports to meet the larger intake flow volume. A short-tube header with a freer-flowing catalytic converter and exhaust system are also installed.

Magnum SOHC Engine Specs
HP Peak: 150 hp @ 6500 rpm
Torque Peak: 135 ft/lb @ 4800 rpm
Redline: 6500 rpm
Rev Limiter: 6750 rpm
Compression: 9.8 to 1
Bore x Stroke: 3.44 in x 3.27 in
Recommended Gas: 91 octane

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2002.3 SRT Dual Overhead Cam (DOHC)


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2002.4Export (SOHC)

1.8L: TBW.

1.6L: TBW
Plans to put the 1.6L I4 motor that was co-designed with BMW were scrapped at the very last minute. That's why this motor still appears in the Factory Service Manual.

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2002.5 Engine Questions and Answers:

2002.5.1 Q: Which engine is better, the first- or second-generation?
A: Between base SOHC engines, the second-generation engine is smoother and quieter, while maintaining the same power levels as the post-'95 m/y SOHC.. A no-brainer. The real question is, which is better - Magnum SOHC or first-gen DOHC?

Nearly everyone will agree that the published horsepower of the DOHC was a little overrated; the Magnum engine, however, comes much closer to that figure in stock form and puts out an honest 150 crank hp. However, the DOHC is inherently more tunable by virtue of its separate cams, is designed to rev higher, and benefits from seven years of experimentation and tweaking. Time will tell if the Magnum can reach the same level; but the engine certainly has the potential to do so.

2002.5.2 Q: What are the different camshaft specifications for the SOHC models?
A: Here are the OEM cam specifications, along with two popular aftermarket cams for comparison.
Part Number Model Year/Engine Lobe Lift at zero lash (mm) Duration @ 0.5mm Valve Open @ 0.5mm Valve Close @ 0.5mm Overlap at 0.5mm
4667667 1995 2.0L SOHC Intake
4.9 (ATDC)
43.7 (BBDC)
41.7 (ABDC)
5.4 (ATDC)

4777128 1996-2004 2.0L SOHC Intake
13.9 (ATDC)
43.7 (BBDC)
41.1 (ABDC)
5.4 (ATDC)

4884325AA 2001 2.0L SOHC Magnum Intake
13.4 (ATDC)
45.2 (BBDC)
13.4 (ATDC)
45.2 (BBDC)

4884325AB 2002-2004
2.0L SOHC Magnum
12.6 (ATDC)
45.2 (BBDC)
3.3 (ATDC)
45.8 (ABDC)

158-0012 Crane #12 Intake
158-0014 Crane #14 Intake
2002.5.3 Q: Why do the two engines have different octane recommendations?
A: The base and Magnum SOHC engines have different engine controller programming. For increased performance, the Magnum carries more aggressive spark advance tables, and is calibrated for optimum output on 91 octane. The base SOHC is optimized for 87 octane 'regular' grade fuel.

Click here for more information concerning octane ratings.

2002.5.4 Q: How does the Magnum's active intake manifold work?
A: The two-stage intake manifold is an interesting design that allows the the engine to tune the intake stream to suit the particular conditions of the moment. The manifold itself consists of two sets of runners: longer, small-bore primaries (higher velocity, lower volume), and short, fat secondaries (lower velocity, higher volume.) Manifold Tuning Valves (MTVs) located in the secondary runners are controlled by the PCM in response to engine speed and throttle position. The secondaries are normally closed except at wide open throttle (WOT), under the following circumstances:
  • The MTVs open at low revs (below 3200 rpm) to improve cylinder filling when intake vacuum pressure/velocity is weak. This provides good throttle response and makes the car feel more torquey.
  • Between 3200 and 5000 rpm, the secondaries are closed, forcing air through the longer primary runners only. This improves air velocity once the intake vacuum is stronger, maintaining the faster cylinder fill rate. Longer runners help improve midrange torque under most driving conditions.
  • Above 5000 rpm, the secondaries open again to provide the largest possible volume of intake air. Velocity is maintained by the high-rev demand load.
In addition to the simple mechanics of providing additional air volume when needed, the active manifold helps to tune the intake pressure waves in the same way a header is tuned to the pressure waves of the exhaust stream. Having two different types of runners helps broaden the range over which the optimum pressure tuning is applied. This allows for good midrange torque without the corresponding loss of high-end horsepower found in a single-runner design.

Thanks to Chris01RedACR for some of this information.

2002.5.5 Q: What oil should I use?
A: The factory recommended oil for both SOHC engines is 5w-30, year round. See the Owner's Manual for oil change intervals, which vary by use. Click here for more information concerning oils.
2002.5.6 Q: What oil filter should I use?
A: Click here for more information concerning oil filters.
2002.5.7 Q: What spark plugs should I use? What is the correct gap?
A: Click here for more information concerning spark plugs.
2002.5.8 Q: What is OBD II? What are 'error codes'?
A: OBD stands for "On Board Diagnostics", and is a federally-mandated system in which cars monitor their own performance to help reduce emissions problems. The second generation cars, instead of flashing the CEL, simply show the error codes in the digital odometer. They also provide more detail than the original codes do, simplifying interpretation. While the codes can be checked with the same ignition key ON-OFF-ON-OFF-ON cycle, please note that the information codes returned are different from those for the older car.

Click here for more information concerning OBD II and error codes from the FAQ.

Click here for more information concerning OBD II and error codes from a public service website sponsored by the makers of a line of diagnostic tools. This includes a look-up menu for the second generation error codes.

2002.5.9 Q: Is the second generation SOHC an 'interference' design?
A: Yes. The new SOHC engines are still an interference design, meaning that the valves (if open) will conflict with the piston in its highest position. This only happens if the timing belt fails, or is mis-timed by 3 cam sprocket teeth or more, since the valves are normally closed when the piston is at top dead center and the cylinder is firing.

The Neon has a 100,000 mile timing belt; however, it should be inspected periodically. Failure of the timing belt will lead to collisions between pistons and valves, causing extensive (and expensive) engine damage.

The timing belt can be easily inspected by removing the plastic cover over the right-hand side. Look for any frayed or worn areas. Turning the engine over with the coil wire removed will allow you to inspect the whole belt one section at a time.

2002.5.10 Q: What do the rev limiter and the speed limiter do?
A: In order to prevent damage caused by over-revving, the rev limiter interrupts fuel injector pulse-width in order to bring the rpm below redline. The fuel cutoff is relatively sudden, and can cause throttle-off over steer if encountered while cornering near the limits of adhesion. Note that this works only while accelerating! The Neon's manual transmission is very strong, and can be forced into low gears at high speeds. The car's momentum will drive the engine past the redline, and the rev limiter will not help in this situation. If the over speed is bad enough, serious damage will result, so shift carefully! If shifted manually, the 2000-01 three speed automatic will also downshift at over-rev speeds, if forced to do so. The 2002+ four speed ATX, however, is electronically controlled and will not shift until it is safe.

As listed in the table for each engine, the SOHC rev limiter steps in at 6750 rpm. Both manual and automatic transmission cars are subject to this governor.

The speed limiter operates in a similar manner, based on indicated speed rather than rpm. This is done to prevent consumers from exceeding the speed rating of the OEM tires. All Neons (except ACRs and R/Ts) are governed at 118 mph, the maximum speed allowed on a T-rated tire.

2002.5.11 Q: Is there any parts interchangeability between the two SOHC motors? What about the older generation?
A: As mentioned above, the SOHC camshafts can be interchanged between all versions of the SOHC. However, some cams have specific valve spring requirements that must be followed. The engine internals are largely the same between all versions of the SOHC. The most common question would probably be whether the Magnum intake setup can be fitted to a non-Magnum, or first-gen car. The answer here is yes, but controlling the MTV requires an RPM activated switch and some careful wiring work.
2002.5.12 Q: Are stiffer motor mounts available for the PL2k?
A: The stock motor mounts seem to be more durable than their predecessors. However, their primary job is still to damp vibration rather than to provide quick shifts and reduce wheel hop. Travis McMillan at Deyeme Racing makes stock mounts filled with a stiff rubber compound that limits drive train movement without excessive vibration at idle. Rex Inserts are also available for the second gen car.
2002.5.13 Q: Placeholder for 00, 01-02, 03-05 PCM differences

2002.5.14 Q: Is there a difference between the Magnum and base engine controllers? What about ATX and MTX?

A: The power train control module, or PCM, is unique to a given model year, transmission, and engine type. The unit itself is interchangeable; however, the programming varies by car options. Each type carries a different part number, which refers to the correct software flashed into the EEPROM chip inside. Second-gen cars are much less tolerant of modifications to the PCM, due to increased complexity and anti-theft devices such as the SKIM (Sentry Key Immobilizer System.) These make it difficult to replace or modify the PCM without access to a DRB scan tool, in order to flash the vehicles VIN into the new controller. Consequently, aftermarket controllers are only available for a few models and years.

The PCM for second generation cars is located under the hood, on the radiator core support, near the throttle body.

2.5.20 Q: What are the similarities between the 2.4 litre DOHC and the Neon's 2.0 DOHC?
A: The 2.4 litre DOHC engine found in many of the US-designed Chrysler Group cars - the first generation JA series (Cirrus, Stratus, Breeze) - is fundamentally similar to the Neon's 2.0 litre DOHC. The engine shares the same bore diameter and spacing, with 1" longer stroke providing the extra displacement and torque. The longer stroke means that the short block has a 1" higher deck height than the 2.0. While the accessory layout is basically similar to the 2.0, the oil pump and filter location is different, and the accessory brackets, etc. do not interchange. This engine is also found in minivans as well, with slightly less in common among the accessories.

The 1995-2000 2.0 litre DOHC and 2.4 litre DOHC bare cylinder heads are identical, carry the same Mopar part number (p/n 4777541) and will bolt onto either block and both sets of manifolds. The valves, keepers, followers, and lash adjusters are also identical, so the Neon's DOHC engine can benefit from the improved partsdeveloped for the bigger engine. A running change made during the 2000 model year was the move to 3-bead keepers on the valves instead of the single bead that was in use. The 3-bead keepers provide for valve rotation which keeps the stems and seats cleaner to prevent misfire.

The 2.4's cams have lower lift but longer duration (since the 2.4 is a longer stroke engine) than the 2.0. Both sets of cams will physically fit in either engine but the profiles are not well suited to the wrong application. Also, the cam timing magnet, which is read by the cam position sensor as it rotates, is located 90 degrees off between the two cams, which leads to timing issues unless accommodated. Note that all 2.4s are a non-interference design, unlike the 2.0.

The 2001+ 2.4 head design has been updated and offers somewhat better flow through in stock form. The 2001 2.4 DOHC cylinder head has the same size intake valves as prior versions (same part number as the late 2000 3-bead keeper valve), but smaller exhaust valves. In the stock application, the smaller exhaust supposedly flows better and the revised port transfers less heat into the head for quicker catalyst light-off after a cold start. It is not yet clear whether the revised 2001 exhaust ports and valves would flow better than the old style in a race engine with more cam and more revs than a stock 2.4 uses. The coolant passages insde the 2001 head were also revised for better cooling and reduced knock tendency.

The improved 2.4 DOHC head will not bolt directly to the first-generation manifolds, though it can be adapted with some drilling and tapping. It requires the second generation valve cover as well. Depending upon the cylinder head's production date, it may have an enlarged oil drain passage on the front side which requires a 2002+ block date and correct head gasket. However, as noted above, the improved valve train components are a direct fit in the first generation 2.0 DOHC head and are a recommended upgrade for anyone taking their engine apart or planning to race.

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Neon Transmission Information

2002.6 Automatic Transmission (ATX)

The original Neon automatic transmission was a three-speed, mechanically-controlled unit derived from the transmission found in millions of Chrysler FWD cars throughout the 1980s and early 90s. It is an older Chrysler design, and as such, is a reliable, durable transmission. Shifts are regulated by throttle position via a cable attached to the throttle body, while an internal governor sets the maximum upshift speed at 6500 rpm. It has a PCM-controlled lockup torque converter for improved mileage, but no overdrive like the manual has. All 2000 and 2001 m/y ATX Neons featured this transmission.

During the second generation model run, the Chrysler engineers finally overcame the cost and heat/durability problems that kept the Neon with a well-developed but outdated automatic transmission. The 2002+ m/y Neons now feature an electronically controlled, four-speed automatic also found in the midsize Chrysler products such as the Stratus/Cirrus/Sebring, etc. and the minivans. This transmission has not proven as durable as the 31TH in other Chrysler applications; it remains to be seen how it serves in the Neon.

The gearing, shift points, and engine control have been modified somewhat for the 2003 m/y, in order to correct some sub-optimal performance in the 2002 four-speed cars. At present I do not know if this revised programming can be flashed into earlier cars.

31TH Automatic Transmission Specs
Application: 2000-2001
Final Drive 2.98
First 2.69
Second 1.55
Third 1.00
Torque Rating: 170 ft/lbs (approx.)
Control: Hydraulic
Used in: All ATX models

The "31TH" nomenclature derives from the design of the transmission itself. It is a 3 forward speed transmission of level 1 torque capacity, designed for Transverse (FWD) mounting, and it is Hydraulically controlled. The newer 4 forward speed, level 1 torque capacity, Transverse mounted, Electronically controlled transmission is shown in the table below. This style of decoding can be used with the rest of the Chrysler-Group automatic transmission line, as well.

41TE Automatic Transmission Specs
Application: 2002-2003
Final Drive 3.91
First 2.84
Second 1.57
Third 1.0
Fourth .69
Torque Rating: 245 ft/lbs (approx.)**
Control: Electronic
Used in: All ATX models

** The 41TE Transmission is also used behind the LH cars (300m, Concord, LHS,) PT Cruiser, RS minivans (Caravan, Voyager,) and the JR sedans (Stratus, Sebring) sedans. The motors (2.4L, 2.7L, 3.2L, 3.3L, 3.5L, 3.8L,) in those vehicles push out considerable more torque than the 2.0L

40TE Automatic Transmission Specs
Application: 2003+
Final Drive .
First .
Second .
Third .
Fourth .
Torque Rating: . ft/lbs (approx.)
Control: Electronic
Used in: All ATX models

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2002.7 Manual Transmission (MTX)

The Neon manual transmission is a five-speed unit that comes in two main varieties, as described in the table below. The standard transmission retains the 3.55 final drive ratio from the original SOHC cars. However, the ratios were tightened up slightly during the 2000 m/y as fifth gear was shortened slightly, while first and second gear were made taller. For the 2003 m/y, fifth gear was made taller still to improve cruising noise and economy. The performance transmission retains the 3.94 final drive, combined with the more closely-spaced ratios of the revised 5 speed. Internal improvements increased the torque rating, also.

All second-gen Neons use the modular clutch assembly. For the 2001 m/y, the clutch actuator was changed from the old cable style to a new hydraulic unit. The transmission itself remained the same, while the bell housings are specific to the type of actuator. Cars of one style can be converted to the other by installing the actuator parts and switching the bell housing to the appropriate type for the actuator. Differential turning torque should be checked when swapping bell housings though

Note that the Neon's manual transmission is a New Venture design, and is fundamentally common with the GM J-body line (Cavalier, Sunfire, etc.)

Click Here for the cross reference chart

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2002.8 Transmission Questions and Answers:

2002.8.1 Q: What automatic transmission fluid should I use?
A: Click here for more information concerning automatic transmission fluid (ATF).
2002.8.2 Q: How can I increase performance for my automatic transmission?
A: Click here for more information concerning automatic transmission modifications.

The second generation three-speed ATX is essentially identical to the first generation, and can be modified the same ways. The new four-speed unit, however, is internally and externally different. Since shift points are controlled electronically, the TCM (or PCM in NGC cars) determines its operation. Modifying its performance is a matter of reprogramming, and to date no aftermarket unit is available for the 2002+ m/y cars. Hopefully the issues currently preventing modifications to the 2002+ TCM (or PCM in NGC cars) will be overcome. Howell Automotive has shown a commitment to ATX performance and will likely release a unit if possible. Someone with a good knowledge of electronics could theoretically build a manual switchbox to control the shifting as well.

The 41TE is common among many Chrysler products. Like the three-speed, it is possible that another vehicle can provide shorter transfer gears for the Neon. However, given its newness, this does not appear to have been investigated yet.

2002.8.3 Q:Where do babies come from? (placeholder)
A: Ask your father.

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