HARD TO DEPRESS GAS PEDAL WHEN DISPLACEMENT ON DEMAND KICKS IN

Tiny
JSLIGH34
  • MEMBER
  • 2006 CHEVROLET IMPALA
  • 5.3L
  • V8
  • FWD
  • AUTOMATIC
  • 111,000 MILES
Hello,

I have been noticing that while on the freeway and displacement on demand is in effect, switching from 8 cyl mode to 4 cyl mode, I am able to notice and it gets harder and takes more effort to press the gas pedal down and make the car go faster and back into 8 cyl mode. I also have to push the pedal down a little further than normally expected. This has just started happening a few weeks ago and I have no idea why. Everything else with the car seems good, no CEL light and it runs smoothly while in 8 cyl mode. Would you have any idea about this? Plugs and wires are brand new, fuel pump is brand new.
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Wednesday, December 11th, 2013 AT 1:38 PM

3 Replies

Tiny
TY ANDERSON
  • EXPERT
The Displacement On Demand (DOD) system uses engine oil to deactivate cylinders so check the engine oil to make sure its not low.
If there are no diagnostic fault code active or stored in the vehicle's computer
You may have an oil pressure issues within the DOD system (relief valve for example will bleed off any pressure in the DOD system and cause low pressure within the engine oil system but this is usually accompanied with engine ticking).
The DOD system activates under light loads and a steady throttle above 40 mph.
Let me know if you have any questions
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Wednesday, December 11th, 2013 AT 7:54 PM
Tiny
JSLIGH34
  • MEMBER
Hello Ty,

Thanks for your response. I'm certain the engine oil level isn't low because I just changed it on Sunday with the 6 quarts that it takes. If it was low prior, would it take a while for the oil to get through and make a difference?

I don't hear any engine ticking, but how could I check for low oil pressure in the system? If not this, do you think it could be fuel related?

It's just weird, when I'm coasting on the fwy it will show the 4 cyl mode on the dash (which is correct) and then as soon as I hit the gas pedal it will show 8 cyl mode but it's hesitant to get the power up. The rpms drop and then as I push harder and down more on the gas pedal, it goes back to normal and rpms rise.
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Wednesday, December 11th, 2013 AT 8:23 PM
Tiny
TY ANDERSON
  • EXPERT
I looks like everything is working as it should to some degree. It should however, be a smooth transition between V4 and V8 modes. I haven't come across this issue before. The only issues I've seen with the DOD system is reduced oil pressure (ticking) and solenoids no switching.
When you press down further on the gas pedal and it is switching from 4v to 8v proves the vehicle's computer is recognizing the change (input data to the computer) but nothing good happens (output result).
One possibility could be a programing issue.
I've searched GM's technical service bulletins and haven't found any reoccuring issues relating to what your experiencing.

If it was fuel related I would assume this hesitation would happen all the time no just when in V4 and accelerating.
Lastly check the transmission fluid when hot to see if it is low.
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Thursday, December 12th, 2013 AT 7:48 PM

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