Stumbles under all conditions except over 3000 rpm. Oxygen sensor?

Hey Karen.. I do not recall what all has been done,...try this.... While you are sitting still, vehicle in park,see if the engine will rev over 2500 rpm?... try holding the engine at 3000 rpm.. see if it will stay at 3000 rpm.. If it does, try 3500 rpm... see if it will stay at 3500 rpm... try this and let me know what happens.... ??when it stops does it sound like its running out of gas??? remind me what vehicle/make/model. etc we are working on .. please...
Karen, use the comment section to reply.. please mark as helpful.. we can connect through comments.. ( I just happened to stumble upon this!!).. Thanks..

Bad coolant temp sensor is telling ECU engine is warm when it is still cold. Kind of like running with no choke function. Easy fix.

I have a 2000 Chevy Tahoe that did the same thing. I changed the oil pump, new oil, and head gasket. It now has power and doesn't fall on its face when I step into the throttle hard. Hope this helps.

could be as simple as an o2 sensor or your trans may be in limp mode meaning it shuts down only can go about 25 mph or less to prevent further damage

The code P0401 is often not a problem with the EGR valve itself. Rather, the EGR system is not allowing enough EGR to flow back into the combustion process to sufficiently cool the peak firing temperatures. Once the code P401 has been retrieved with a scan tool, the freeze frame data should be documented and analyzed in order to determine what engine conditions were present when the code was triggered. It is recommended that the vehicle be driven in such a way as to duplicate the code setting conditions with a data streaming scan tool connected, so the behavior of the EGR actuating components and feedback sensors can be monitored.
Common Tests to Determine Whether the Problem Is an EGR Control Problem, a Plugged or Restricted System, or a Defective Feedback Device

• Does the engine die, not just stumble, when the EGR valve is manually raised to its maximum?
  (Use either a vacuum pump or bi-directional scan tool if it's a digital EGR valve.)
• Is the EGR valve getting sufficient vacuum? (Use the manufacturer EGR vacuum spec.)
• Is the EGR system restricted? (The engine stumbles, but does not die.)
• Is the EGR system plugged? (Engine RPM does not change.)
• Does the EGR valve work?
• Raise the RPM to 3000 and check manifold vacuum. Then open the EGR valve to its maximum-the manifold vacuum should drop by at least 3" of mercury. If it does not, there is a flow and/or restriction problem.
• Test the EGR temperature sensor (if equipped) with a propane torch and a DVOM.
• Test the accuracy of the EGR valve position sensor with a scan tool or DVOM by raising or lowering the EGR valve.
• Test the Digital EGR Pressure Feedback Sensor (DPFE) with a data streaming scan tool to verify that the voltage or lift percentage changes according to spec.
• Verify that the front Oxygen Sensor readings drop and the Short Term Fuel Trim increases when the EGR valve opens. (EGR leans out the mixture.)

p0172 Basically this means that an oxygen sensor in bank 1 detected a rich condition

p0316 crankshaft position sensor

clean your intake and check you cap / rotor

Hi Galant5Rov,

Firstly, congratulations to you on identifying the Trouble Code. This code relates to the Heated Oxygen Sensor (H02s)

The oxygen sensors supply the computer with a signal that indicates a rich or lean condition during engine operation (i.e. fuel/air metering).

This input information assists the computer in determining the proper air/fuel ratio. A low voltage signal from one or more sensors indicates too much oxygen in the exhaust (lean condition) and, conversely, a high voltage signal indicates too little oxygen in the exhaust (rich condition).

The oxygen sensors are threaded into the exhaust manifold and/or exhaust pipes on all vehicles.

A faulty oxygen sensor due to loose connections, bad grounds, high resistance in the circuit, or opens in the circuit can cause the following symptoms.
Related Symptoms

• Surging at idle
• Unstable idle
• Running rough off idle
• Hesitation
• Stumble
• Chuggle
• Poor fuel economy
• Spark knock
• Stalling on acceleration

You must take EXTREME care when removing these sensors, as they can be difficult to remove (seize up). You may require a special tool to remove these without causing damage to the sensor.

Cheers,


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if the car is stock i would replace your oxygen sensor. you may also need to clean out the MAF sensor.

there is a either a engine vacuum problem maybe caused by the oxygen sensor not working properly or your fuel filter needs to be replaced.

My 2001 Dakota now works fine, I took it to a good reliable shop after much frustration. The problem was the crank position sensor in combination with an bad oxygen sensor. This was a very unusual problem with no consistency therefore hard to diagnose. Crank sensor $190.00 cdn oxygen sensor $130.00 cdn $300.00 in troubshooting, repair and diagnostics. Repaired by Gerald at AutoPro in Corner Brook, Newfoundland. Thanks Gerald