Hi All,
Here, I have a 2003 Dodge Neon SXT. I bought it from a used car dealer in the UK in 2010. I took it to Nigeria and I have frequently driven it for short and long journeys since then. While traveling at night in 2017, I ran over a bump and the engine oil sump ruptured. The engine leaked off and before I knew what was happening the engine seized. Eventually, I replaced the engine and transmission with used ones. I maintain the car to the best of my ability and availability of parts. Dodge Neons are few and far apart in Nigeria. One can crisscross the country for months and not find another Neon. Other Dodge variants are more common though. Even at that, I have tried to take good care of my Neon. People admire it everywhere I go because it looks different from all other cars around. The car has been a breeze on the road until eight months ago when it started to appear to struggle to accelerate. The problem has increased with time and now, it would almost come to a halt when going uphill. Even on level road, it go as fast as 100 km/h. The car seems to have problems breathing. I have replaced the air filter, replaced spark plugs, injectors, throttle position sensor, transmission fluid filter, fuel pump. The last time I changed the timing belt was 2018. This morning, I had a mechanic look at the timing belt. He told me there was nothing wrong with it. Right now, I do not know what else to do about this problem. I left the car at the mechanic shop.
The car does not have PCM error code, no TCM error code, but it does have SRS error codes which it has had since the day I bought it. A snapshot of the data stream I recorded from the car two days ago is shown below. Please, please spare me the time to look at it and oblige me with your thoughts. Thank you.
************************************************** ************************************************** ********************
1/1 Long Term ADAP: 7.23%
1/1 Short Term ADAP (1/12): 7.41%
1/1 O2S Goal (0 - 1): 0.84V
1/1 O2S Goal Volts: 3.84V
1/1 O2S Level (1/12): Low
1/1 O2S Volts: 3.84V
1/1 PWM O2 Heater: 35.29%
1/2 O2S Volts (0 - 1): 0.37V
2/2 O2S Volts: 0V

AC Hi-Side Pressure (1/1): 0 kpa
ACT Man Tune Valve: High
ACT Purge Current: 29.28ma

AMB TEMP DEG: 30 deg
AMB TEMP Volt (1/1): 1.65V
ASD (Auto Shutdown) Relay Sense: High
Barometric Pressure: 745.50 mmHg
BAT TEMP DEG: 34 degC
Brake Switch (1/1): Released

Cam Crank Difference: 4.80
Cam Crank Last Lost: None
Cam Sync At Start: In Sync
Cam Sync State: In Sync
CAT Modeled TEMP DEG: 540 degC
Closed Loop Timer: 0s
Coil 1 Burn Time: 1440us
Crank Sync At Start (1/1): In Sync
Crank Sync State: In Sync
Crank INJ PW: 18.98 ms
Current ADAP Cell ID: 0
Current Fuel Shutoff: N/A

DES ASD (Auto shutdown) Relay: On
DES Double Start 0V: Enabled
DES High Speed Fan: On
DES Malfunction Lamp: Off
DES NVLD Solenoid: (1/1): On
DES Purge Current: 0 mA
DES S/C VAC SOL: Apply
DES S/C Vent SOL: Hold

ENG Coolant TEMP DEG (1/1): 70 degC
Engine rpm: 2371 rpm
Fuel Feedback 2/1: Closed Loop
Fuel Level Percent: 50%
Fuel Pump Relay (1/1): On
Fuel Tank Size: 47.30 L

Generator Duty Cycle: 12.55%
IAC (Idle Air Control) Current: 401.30 mA
IAC (Idle Air Control) PWM (1/1): 32.17%
IAC (Idle Air Control) Total Airflow: 2.52 gm/s
Ignition Dwell CYL 1: 3.94 ms
Ignition Off Time: 0 min
Ignition Run Switch Sense (1/1): High
Ignition Star Switch Sense: Low
Injector PW CYL 1: 2.89 ms
Intake Air TEMP DEG: 33 degC
Intake Air TEMP Volt (1/1): 3.30 V
Map Vacuum: 504 MMV
Map Volts: 1.30 V
Minimum TPS: 0.53 V
NVLD Switch (1/1): Off
Oil Pressure Switch: High PSI
P-Ratio Map/Baro: 0.33%
P/N Position Switch: P/N
PCM (Powertrain Control Module) Odometer (1/1): 183,256.88 km
Power Steering Switch: High PSI
Purge Adaptive: 2091.78%
Purge Airflow: 0.01 gm/s
Purge Duty Cycle (1/1): 10.31%
Purge Mode: Learn Mode

S/C ACC/Res Switch: Released
S/C Cancel Switch: Released
S/C Coast Switch: Released
S/C Cruise IND Lamp: Off
S/C Denied Status: Allowed
S/C Dump: Bleed
S/C On/Off Switch (1/1): Released
S/C Set Speed: 0 km/h
S/C Set Switch: Released
S/C Working Status: 0

Spark Advance (1/1): 46.50 deg
ST Knock Retard: 0
Target Charging VLT: 0.18 V
Target Idle: 744 rpm
Time from Start/Run (1/1): 40.09 min
TPS Calculated Volt: 0.53 V
TPS Percent: 0.66%
TPS Volts: 0.55 V

VEH Speed Signal (1/1): 0 km/h
VEH Theft Security: Fuel On
VEH Theft State: Seen
Voltage Sense: 13.65 V

 

I have eventually taken the car back home. The problem remains - car does not accelerate, struggles to go up any gentle hill. I stumbled across a document on Google and I would appreciate it if you could share your experiences accordingly. Please have a look at the image insert. Thanks.

 

Apologies! I am having challenge with image attachment. It uploads up to 90% and just stops.

 

Okay, having been unable to upload image, I have decided to type in the texts.

Excerpted from "Chapter 12 Chrysler and Jeep Data Parameters - Snap-on"
IAC AIRFLW(g/s)
Idle air control (IAC) air flow measured in grams per second.
• A 4-cylinder engine should read approximately 30–40 g/s at idle. The IAC in my car reads 2.52 gram/s and there is no error code.
• A 6-cylinder engine should read approximately 350 g/s at idle with no load.

IAC CURRENT(mA)
Idle air control motor amperage. The PCM pulse width modulates power and ground to open
or close air passage for idle control. More amperage increases air flow and RPM.
• A 4-cylinder engine should read approximately 400 mA at warm idle. The IAC in my car reads 401.30 mA
• A 6-cylinder engine should read approximately 350–600 mA at idle.

IAC PWM(%)
IAC Pulse Width(%)
Range: __________________________________________________ ________20 to 50% The IAC in my car reads 32.17%
Idle air control motor pulse width modulation percentage.

Please help me resolve the problem. I do not wish to junk this car just yet.

 

Okay, having been unable to upload image, I decided to type in the texts.

Excerpted from "Chapter 12 Chrysler and Jeep Data Parameters - Snap-on"

IAC AIRFLW(g/s)
Idle air control (IAC) air flow measured in grams per second.
• A 4-cylinder engine should read approximately 30–40 g/s at idle. The IAC in my car takes in 2.25 gm/s and there is no error code.
• A 6-cylinder engine should read approximately 350 g/s at idle with no load.

IAC CURRENT(mA)
Idle air control motor amperage. The PCM pulse width modulates power and ground to open
or close air passage for idle control. More amperage increases air flow and RPM.
• A 4-cylinder engine should read approximately 400 mA at warm idle. The IAC in my car produces 401.30 mA
• A 6-cylinder engine should read approximately 350–600 mA at idle.

IAC PWM(%)
IAC Pulse Width(%)
Range: __________________________________________________ ________20 to 50% The IAC in my car has a pulse width of 32.17%
Idle air control motor pulse width modulation percentage.

Please help me resolve the problem. I do not wish to junk this car just yet.

 

Please see the image below

 

I eventually discovered the acceleration problems with my car. The catalytic converter! The diagnostics machine reported Catalyst efficiency: 21%. I replaced catalyst with a used one and the car is back to life. The only PCM error code I have now is P0038 (HO2S Heater control circuit High). The 1/2 O2S Volts (0 - 1) displays 2 V. I am not sure whether the panel beater who did the job of removing the existing catalyst and installing the replacement, tampered with the O2 sensor wiring or whether the sensor got damaged during the job. I will look into this subsequently.