Low engine power?

Tiny
WILLPAT100
  • MEMBER
  • 2012 CHEVROLET IMPALA
  • 3.6L
  • V6
  • 2WD
  • AUTOMATIC
  • 13,000 MILES
Car has 142,000 miles on it. I just replaced engine due to rod bearing. Installed same size and code from another 2012 Impala LT 3.6 LFX NU6 with 13,000 miles into my 2012 Impala LTZ. Had p0420 and p0430 codes dealer finally changed both manifold converters. Engine is slow to accelerate and while doing so at about 4500 RPM's it comes alive until about 5,000 RPM's the loses power. Four new o2 sensors. Resonator was replaced with straight pipe. I did not do a crank position sensor system relearn after engine swap. Could the third catalytic converter cause these issues or the relearn procedure cause this? Gas mileage is a little low maybe 1 or 2 mpg.
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Thursday, June 6th, 2019 AT 2:53 PM

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Tiny
JACOBANDNICKOLAS
  • EXPERT
Welcome to 2CarPros.

Anytime a catalytic converter is partially plugged, it can cause power loss. Have you tried removing the O2 sensors to see if that is the possible issue? Take a look through this link.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

As far as the crankshaft position sensor relearn, anytime an engine is replaced, it has to be done. And yes, that could be part of the problem.

Here are the directions:

_______________________________

CRANKSHAFT POSITION SYSTEM VARIATION LEARN
Crankshaft Position System Variation Learn

Note: The Crankshaft Position System Variation Learn procedure is also required when the following service procedures have been performed, regardless of whether DTC P0315 is set:

* An engine replacement

* A engine control module (ECM) replacement

* A crankshaft balancer replacement

* A crankshaft replacement

* A crankshaft position sensor replacement

* Any engine repairs which disturb the crankshaft to crankshaft position sensor relationship.

Note: The ECM monitors certain component signals to determine if all the conditions are met to continue with the crankshaft position System Variation Learn Procedure. The scan tool only displays the condition that inhibits the procedure. The scan tool displays the signals of the following components:

* Crankshaft position sensors activity-If there is a crankshaft position sensor condition, refer to the applicable DTC that set.

* Camshaft position sensor signal activity-If there is a camshaft position sensor signal condition, refer to the applicable DTC that set.

* Engine coolant temperature (ECT)-If the engine coolant temperature is not warm enough, idle the engine until the engine coolant temperature reaches the correct temperature.

1. Install a scan tool.

2. Monitor the ECM for DTCs with a scan tool. If other DTCs are set, except DTC P0315, refer to Diagnostic Trouble Code (DTC) List - Vehicle See: A L L Diagnostic Trouble Codes ( DTC ) > Diagnostic Trouble Code Descriptions > Diagnostic Trouble Code (DTC) List - Vehicle for the applicable DTC that set.

3. With a scan tool, select the Crankshaft Position System Variation Learn Procedure and perform the following:

1. Block drive wheels.

2. Set parking brake.

3. DO NOT apply brake pedal.

4. Cycle ignition from OFF to ON.

5. Apply and hold brake pedal for the duration of the procedure.

6. Start and idle engine.

7. Turn the air conditioning (A/C) OFF.

8. The vehicle must remain in Park or Neutral.

Note: While the learn procedure is in progress, release the throttle immediately when the engine starts to decelerate. The engine control is returned to the operator and the engine responds to throttle position after the learn procedure is complete.

9. Accelerate to wide open throttle (WOT) and release when the fuel cut-off occurs.

4. The scan tool displays Learn Status: Learned this Ignition. If the scan tool indicates that DTC P0315 ran and passed, the crankshaft position variation learn procedure is complete. If the scan tool indicates DTC P0315 failed or did not run, or another DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle See: A L L Diagnostic Trouble Codes ( DTC ) > Diagnostic Trouble Code Descriptions > Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure.

5. Once the learn procedure has successfully completed, and in order to store the crankshaft position system variation values in the ECM, turn OFF the ignition and verify all vehicle systems are OFF. This may take up to two minutes.
________________________________

Try that and let me know if it helps.

Joe
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Thursday, June 6th, 2019 AT 8:29 PM
Tiny
WILLPAT100
  • MEMBER
Okay, I will let you know about relearn. The dealer did replace both bank 1 and 2 converters! I was playing with it tonight watching the live data on code reader an noticed the ignition advance at idle was 1.4 then at 2500 it was 53 degrees not sure about normal specs are supposed to be.
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Friday, June 7th, 2019 AT 12:37 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Let me know what you find. As far as the timing, that's not unexpected. Also, since you have a live data scanner, can you let me know what the fuel trims are running at, both short and long term?

Take care and I'll watch for your reply.

Joe
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Friday, June 7th, 2019 AT 6:08 PM
Tiny
WILLPAT100
  • MEMBER
Okay update; dealer finally got to it and found the third catalytic converter was plugged. They did the relearn and tech 2 said it passed the test. Going to get it now Finger crossed, Thanks!
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Thursday, June 27th, 2019 AT 1:55 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Welcome back:

That's it. The P0420 indicated a faulty converter. I'm glad to hear they got it figured for you. I'll keep my fingers crossed for you. Let me know how it's running.

Take care,
Joe
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Thursday, June 27th, 2019 AT 3:33 PM
Tiny
WILLPAT100
  • MEMBER
It's fixed, finally! Now one more question. The engine I installed has been sitting in the salvage yards building since late 2012. Should I do anything with the seals on the fuel injectors? I did need to replace the high pressure fuel pump due to it leaking.
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Friday, June 28th, 2019 AT 11:41 AM
Tiny
RENEE L
  • ADMIN
Hi WILLPAT100,

Thank you for using 2CarPros. Can you please start a new question? The question you are asking is about a different issue. In order for the site to properly index your question it needs to be its own question. I have included the link. Please make sure you logged into the site before clicking on the link.

https://www.2carpros.com/questions/new

Have a great weekend!

Renee
Admin

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Friday, June 28th, 2019 AT 3:28 PM
Tiny
WILLPAT100
  • MEMBER
Not a problem, thank you to all who helped me, this site is great!
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Saturday, June 29th, 2019 AT 6:20 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Happy to help.

Take care,
Joe
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Saturday, June 29th, 2019 AT 6:57 PM
Tiny
SAM1978
  • MEMBER
  • 2009 CHEVROLET IMPALA
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 70,000 MILES
I have a 2009 chevy impla and my traction control came one and my car wont go over 40 mph. Can you give me some pointers
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Thursday, September 17th, 2020 AT 11:37 AM (Merged)
Tiny
GMTECH
  • EXPERT
It sounds like the car is in limp in mode with means there is an issue with the transmission/engine traction control. This guide can help us fix it

https://www.2carpros.com/articles/engine-has-low-power-output

Please run down this guide and report back.
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Thursday, September 17th, 2020 AT 11:37 AM (Merged)
Tiny
STARLORD1976
  • MEMBER
  • 2008 CHEVROLET IMPALA
  • 6 CYL
  • 150,000 MILES
When driving down road usually about 40 mph. With my gas pedal in same position my car will slow down and speed up a couple times for no reason. But doesn t do it every time.
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Thursday, September 17th, 2020 AT 11:37 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

That sounds like a fuel pump issue. Has the check engine light been staying on when the engine is running? If it is, the next step is to get the computer scanned for diagnostic trouble codes. Here is a quick video showing how it's done:

https://youtu.be/YV3TRZwer8k

I realize most people don't own a scanner, but often times a parts store will do it free of charge. So, if the light is staying on, have that done and let me know what codes are found.

Now, if the light isn't on, then we need to move to the next thing, fuel pressure. Here is a link that shows how to check it:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Here are the manufacturer's specs for pressure:

Fuel Pressure (Key ON, Engine OFF) .................... 384-425 kPa (56-62 psi)

_________________________________________

Let me know what you find or if you have questions.

Take care,
Joe
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Thursday, September 17th, 2020 AT 11:37 AM (Merged)
Tiny
STARLORD1976
  • MEMBER
Engine light is not on.
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Thursday, September 17th, 2020 AT 11:37 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Okay, then we need to check fuel pressure. Low fuel pressure can cause what you described. Let me know if you need help or have questions.

Take care,
Joe
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Thursday, September 17th, 2020 AT 11:37 AM (Merged)
Tiny
STARLORD1976
  • MEMBER
Do you think this could be the transmission. If so how will I know that.
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Thursday, September 17th, 2020 AT 11:37 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

I doubt it is the transmission. If the transmission was causing this, chances are the engine RPM's would increase when it slows down indicating slippage.
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Thursday, September 17th, 2020 AT 11:37 AM (Merged)
Tiny
STARLORD1976
  • MEMBER
My girlfriend says that this is usually happens about 20 mph and when it happens the rpm's do jump from little over one to 2 then back down.
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Thursday, September 17th, 2020 AT 11:37 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

If the RPM's are increasing but the vehicle slows down, then it does sound like it could be transmission related and is slipping. Have you checked the transmission fluid level and condition? If you look at pics 1 and 2, it explains what to do.

_________________________________________

Let me know.

Joe
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Thursday, September 17th, 2020 AT 11:37 AM (Merged)
Tiny
BJ2
  • MEMBER
  • 2008 CHEVROLET IMPALA
  • 3.5L
  • V6
  • FWD
  • AUTOMATIC
  • 175,000 MILES
Hello, I just finished repairing the wire attached to the camshaft position actuator solenoid. The serpentine belt had chewed through it, that is what causes my engine light to come on. After fixing the problem, the engine light when out on it on.

I have replaced the spark plugs, throttle body, mass air flow sensor, o2 sensors, and air filters. Most were due for change/replacing.

Changing the above mention item, I knew the car had to relearn some of the parts; Evap, secondary air, oxygen sensor monitor, and oxygen sensor heater.

However, when driving to get on the highway, before getting to the highway, I had to go up the hill (thirty degree climb). While going up the hill the car started to shutter and it stops accelerating. I continue my journey to get to the highway to complete the calibration of the mention components. Did not make it because the car just stops accelerating. The only way it would accelerate, for about three seconds interval, is when I press on the gas and take my foot off it fast. I just came back home.

When pressing the gas I can hear the motor drawing loud and I can see the tachometer gauge hand moving, but the car would not accelerate.

I have no trouble with the car start. Put the key in, it starts up. No hesitation or any things. No trouble codes.

Last time timing belt was changed? Two months ago
Last time spark plugs were changed? Two weeks
Last time fuel filter was changed? Have not.
Last time air filter was changed? Two weeks ago.
Are there any error codes? No code on ODB11.
Last time EGR valve was cleaned? Never.
Last time EGR passageways were cleaned? Never.
Last time throttle body was cleaned? New replace six days ago. Email date.
Last time IAC was cleaned? Not sure of this one. Never for me.

I was thinking it could be the transmission, however, when I park it, transmission was working fine. Check oil and transmission fluid, are all fine. Transmission serviced about sixteen months ago.

Thank very much for giving this your attention.
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Thursday, September 17th, 2020 AT 11:37 AM (Merged)

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