Hard Starting, Misfiring and Bucking

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BoostedGS

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00 Dodge Ram 1500 V8(360)

When truck is cold, it has a long crank time to start. Once warmed up fires up right away. It feels like its misfiring very lightly but no codes are being thrown. I have felt bucking but its not a consistent thing. Its bucked a little while cruising 60 mph down the road. And bucked a couple time real hard while accelerating from a dead stop. But like I said never consistent.

It has brand new, less than a month and 100 miles, Copper Plugs, Cap, Rotor, Wires, Coil, IAC and TPS sensors.

I did pop a code for the Upstream 02 Sensor. But I cleared it over a week ago and it hasn't come back on.

I'm thinking its the 02 Sensor or a bad Injector. After work I'm going to go Ohm the Injectors to see what it reads.

Any other ideas?
 
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BoostedGS

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No ideas? I ohm'd the injectors and they all fell in around 14.0-14.4 range. I replaced the MAP Sensor last night and it felt a little better but still hiccuped a little.

Another symptom I'm having is if I turn the truck on and let it just idle, it will idle for a minute or two and the start just sucking air like a ********** sucking the chrome off a door knob. While doing this the engine will start to die, sometimes it will die, other times it will pick itself back up and run normal. I had the fuel pressure gauge hooked up while it was doing this and it held at 50 psi the whole time its dying.

I'm going to reset the computer today to see what that does.
 

dodge dude94

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O2 sensors usually fail when the truck is warm

Have you checked fuel pressure?
 
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BoostedGS

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O2 sensors usually fail when the truck is warm

Have you checked fuel pressure?

Yes, at idle my Fuel Pressure is 50 psi. As stated in my second post, even when its sucking air and dying, it still holds 50 psi through the whole ordeal.
 
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BoostedGS

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Truck still feels under powered and runs like crappy occasionally. I've replaced Coil, Plugs , Wires, cap, rotor, IAC, MAP, TPS and downstream 02 Sensor. Fuel pressure is 50 lbs all day while the truck is running and all injectors have OHM'd out good. I'm completely lost as to what the issue is. Any insight or help would be greatly appreciated!
 

korby05

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Crank position sensor maybe


Sent from my iPhone using Tapatalk
 
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BoostedGS

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Well I found out my Catalytic Converter was clogged go I cut it out and straight piped it. It seems to fix the issues after the vehicle warms up. But I still have the Bucking, Misfiring and falling on itself when its cold.

Any Ideas?
 
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BoostedGS

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So as it stands now, The truck has hard starting issues when cold and it feels like its misfiring and bogging out while stepping on the throttle. After it warms up, I still feel the misfiring but aside from that the truck runs normal. Just feels underpowered.
 

Huskyd

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When your truck does the bucking when exactly does it do it? Mine always does it when I accelerate slow but if I give it a little gas it's usually smooth.
 
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BoostedGS

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When your truck does the bucking when exactly does it do it? Mine always does it when I accelerate slow but if I give it a little gas it's usually smooth.

Most times it does it like how you said yours has. Almost always right after I start the truck and pulling away from a dead stop or low speeds. Once it did it to me while cruising at about 60 mph
 
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BoostedGS

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Well today I was merging onto the interstate and the truck finally popped a code for Bank 1 Sensor 1 Oxygen Sensor. So hopefully once I replace that it will run right!
 
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BoostedGS

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Well today I was merging onto the interstate and the truck finally popped a code for Bank 1 Sensor 1 Oxygen Sensor. So hopefully once I replace that it will run right!

So as I posted my B1S1 02 popped a code. Later that night after sitting for a while I went to drive it and the check engine light was no longer on. But I replaced the sensor anyways and so far it has seemed to have fixed my issue. The truck still has a hard starting issue and feels a bit powerless and feels like it idles a little rough. But I haven't had any of the bucking, stalling or falling on itself while driving issues I had before. So for now it looks like it was the Upstream 02 Sensor this whole time causing my problems.
 

WarrenRam

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I didn't realize an oxygen sensor could cause such issues. I was going to suggest that you clean the TB real good if you haven't already done so.

By the title of the thread, I thought this was going to be about my sex life!! *rimshot!* :naughty:
 

dodge dude94

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I didn't realize an oxygen sensor could cause such issues. I was going to suggest that you clean the TB real good if you haven't already done so.

By the title of the thread, I thought this was going to be about my sex life!! *rimshot!* :naughty:

:roflsquared:



Did you reset the PCM while installing the new O2? If not, do so.
 

xb1230

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I agree with WarrenRam on the throttle Body clean-up. Make sure it's clean and the TB cleaner you use has no 2K.

reading the service manual for my '02, I have not found any procedure to "reset" the PCM. It ususally is a self learning process, and also a work in parallel with the ECM to regulate the Air/Fuel misture.

That being said in order to understand the influence of all the sensors including the O2 on the engine fuel system management, here is a little extract from the service manual of the '02 RAM which explains the 2 modes the PCM operates under (Open Loop mode and Closed Loop mode) :
______________________________________________________________
Powertrain Control Module (PCM)
DESCRIPTION - MODES OF OPERATION

As input signals to the Powertrain Control Module (PCM) change, the PCM adjusts its response to the
output devices. For example, the PCM must calculate different injector pulse width and ignition timing for idle than it does for wide open throttle (WOT).
The PCM will operate in two different modes:
Open Loop and Closed Loop.
During Open Loop modes, the PCM receives input signals and responds only according to preset PCM programming. Input from the oxygen (O2S) sensors is not monitored during Open Loop modes. During Closed Loop modes, the PCM will monitor the oxygen (O2S) sensors input. This input indicates to the PCM whether or not the calculated injector pulse width results in the ideal air-fuel ratio. This ratio is 14.7 parts air-to-1 part fuel. By monitoring the exhaust oxygen content through the O2S sensor, the PCM can fine tune the injector pulse width. This is done to achieve optimum fuel economy combined with low emission engine performance. The fuel injection system has the following modes of operation:
- Ignition switch ON
- Engine start-up (crank)
- Engine warm-up
- Idle
- Cruise
- Acceleration
- Deceleration
- Wide open throttle (WOT)
- Ignition switch OFF

The ignition switch On, engine start-up (crank), engine warm-up, acceleration, deceleration and wide open throttle modes are Open Loop modes.
The idle and cruise modes, (with the engine at operating temperature) are Closed Loop modes.

______________________________________________________________
 

xb1230

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Here is also the details about all the operating modes for the PCM as described above
______________________________________________________________
IGNITION SWITCH (KEY-ON) MODE
This is an Open Loop mode. When the fuel system is activated by the ignition switch, the following
actions occur:
² The PCM pre-positions the idle air control (IAC) motor.
² The PCM determines atmospheric air pressure from the MAP sensor input to determine basic fuel
strategy.
² The PCM monitors the engine coolant temperature sensor input. The PCM modifies fuel strategy
based on this input.
² Intake manifold air temperature sensor input is monitored.
² Throttle position sensor (TPS) is monitored.
² The auto shutdown (ASD) relay is energized by the PCM for approximately three seconds.
² The fuel pump is energized through the fuel pump relay by the PCM. The fuel pump will operate for approximately three seconds unless the engine is operating or the starter motor is engaged.
² The O2S sensor heater element is energized via the ASD or O2S heater relay. The O2S sensor input is not used by the PCM to calibrate air-fuel ratio during this mode of operation.

ENGINE START-UP MODE
This is an Open Loop mode. The following actions occur when the starter motor is engaged.
The PCM receives inputs from:
² Battery voltage
² Engine coolant temperature sensor
² Crankshaft position sensor
² Intake manifold air temperature sensor
² Manifold absolute pressure (MAP) sensor
² Throttle position sensor (TPS)
² Camshaft position sensor signal
The PCM monitors the crankshaft position sensor. If the PCM does not receive a crankshaft position
sensor signal within 3 seconds of cranking the engine, it will shut down the fuel injection system.
The fuel pump is activated by the PCM through the fuel pump relay. Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control the injection sequence and injector pulse width by turning the ground circuit to each individual injector on and off. The PCM determines the proper ignition timing according to input received from the crankshaft position sensor.

ENGINE WARM-UP MODE
This is an Open Loop mode. During engine warmup, the PCM receives inputs from:
² Battery voltage
² Crankshaft position sensor
² Engine coolant temperature sensor
² Intake manifold air temperature sensor
² Manifold absolute pressure (MAP) sensor
² Throttle position sensor (TPS)
² Camshaft position sensor signal
² Park/neutral switch (gear indicator signal—auto. trans. only)
² Air conditioning select signal (if equipped)
² Air conditioning request signal (if equipped)

Based on these inputs the following occurs:
² Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control
the injection sequence and injector pulse width by turning the ground circuit to each individual injector
on and off.
² The PCM adjusts engine idle speed through the idle air control (IAC) motor and adjusts ignition timing.
² The PCM operates the A/C compressor clutch through the A/C compressor clutch relay. This is done
if A/C has been selected by the vehicle operator and specified pressures are met at the high and low–pressure A/C switches. Refer to Heating and Air Conditioning for additional information.
² When engine has reached operating temperature, the PCM will begin monitoring O2S sensor
input. The system will then leave the warm-up mode and go into closed loop operation.

IDLE MODE
When the engine is at operating temperature, this is a Closed Loop mode. At idle speed, the PCM
receives inputs from:
² Air conditioning select signal (if equipped)
² Air conditioning request signal (if equipped)
² Battery voltage
² Crankshaft position sensor
² Engine coolant temperature sensor
² Intake manifold air temperature sensor
² Manifold absolute pressure (MAP) sensor
² Throttle position sensor (TPS)
² Camshaft position sensor signal
² Battery voltage
² Park/neutral switch (gear indicator signal—auto. trans. only)
² Oxygen sensors

Based on these inputs, the following occurs:
² Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control
injection sequence and injector pulse width by turning the ground circuit to each individual injector on
and off.
² The PCM monitors the O2S sensor input and adjusts air-fuel ratio by varying injector pulse width.
It also adjusts engine idle speed through the idle air control (IAC) motor.
² The PCM adjusts ignition timing by increasing and decreasing spark advance.
² The PCM operates the A/C compressor clutch through the A/C compressor clutch relay. This is done if A/C has been selected by the vehicle operator and specified pressures are met at the high and low–pressure A/C switches. Refer to Heating and Air Conditioning for additional information.

CRUISE MODE
When the engine is at operating temperature, this is a Closed Loop mode. At cruising speed, the PCM
receives inputs from:
² Air conditioning select signal (if equipped)
² Air conditioning request signal (if equipped)
² Battery voltage
² Engine coolant temperature sensor
² Crankshaft position sensor
² Intake manifold air temperature sensor
² Manifold absolute pressure (MAP) sensor
² Throttle position sensor (TPS)
² Camshaft position sensor signal
² Park/neutral switch (gear indicator signal—auto. trans. only)
² Oxygen (O2S) sensors

Based on these inputs, the following occurs:
² Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then adjust the injector pulse width by turning the ground circuit to each individual injector on and off.
² The PCM monitors the O2S sensor input and adjusts air-fuel ratio. It also adjusts engine idle
speed through the idle air control (IAC) motor.
² The PCM adjusts ignition timing by turning the ground path to the coil(s) on and off.
² The PCM operates the A/C compressor clutch through the clutch relay. This happens if A/C has been selected by the vehicle operator and requested by the A/C thermostat.

ACCELERATION MODE
This is an Open Loop mode. The PCM recognizes an abrupt increase in throttle position or MAP pressure as a demand for increased engine output and vehicle acceleration. The PCM increases injector pulse width in response to increased throttle opening.

DECELERATION MODE
When the engine is at operating temperature, this is an Open Loop mode. During hard deceleration, the PCM receives the following inputs :
² Air conditioning select signal (if equipped)
² Air conditioning request signal (if equipped)
² Battery voltage
² Engine coolant temperature sensor
² Crankshaft position sensor
² Intake manifold air temperature sensor
² Manifold absolute pressure (MAP) sensor
² Throttle position sensor (TPS)
² Camshaft position sensor signal
² Park/neutral switch (gear indicator signal—auto. trans. only)
² Vehicle speed

If the vehicle is under hard deceleration with the proper rpm and closed throttle conditions, the PCM
will ignore the oxygen sensor input signal. The PCM will enter a fuel cut-off strategy in which it will not
supply a ground to the injectors. If a hard deceleration does not exist, the PCM will determine the proper injector pulse width and continue injection.

Based on the above inputs, the PCM will adjust engine idle speed through the idle air control (IAC) motor. The PCM adjusts ignition timing by turning the ground path to the coil on and off.

WIDE OPEN THROTTLE MODE
This is an Open Loop mode. During wide open throttle operation, the PCM receives the following
inputs:
² Battery voltage
² Crankshaft position sensor
² Engine coolant temperature sensor
² Intake manifold air temperature sensor
² Manifold absolute pressure (MAP) sensor
² Throttle position sensor (TPS)
² Camshaft position sensor signal

During wide open throttle conditions, the following occurs:
² Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control the injection sequence and injector pulse width by turning the ground circuit to each individual injector on and off. The PCM ignores the oxygen sensor input signal and provides a predetermined amount of additional fuel. This is done by adjusting injector pulse width.
² The PCM adjusts ignition timing by turning the ground path to the coil(s) on and off.

IGNITION SWITCH OFF MODE
When ignition switch is turned to OFF position, the PCM stops operating the injectors, ignition coil, ASD relay and fuel pump relay.

______________________________________________________________

So basically monitoring these sensors with an OBDII compliant device would potentially allow you to understand where the issue is and why the engine is behaving in this manner.

There are very cheap OBDII USB wired and Bluetooth adapaters available that can be hooked up to your laptop or smartphone and come with apps that will allow you to read the values returned by these sensors in order to troubleshoot. IMHO these adapters are way better than any OBDII code readers as they can do a lot more for often times a lot cheaper. (But again this my personal opinion)

Hope this will help you resolve your bucking problem.
 
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