silverspark78

Mpg lowered curious why

6 posts in this topic

When I took my car in for maintenance work (17 spark lt cvt) they performed a recall 18089 which has some kind of programming I guess with the cvt. Ever since then the mpg average had gone gm down by maybe 5 or 6 from what I'm used to in the city. Would this update cause it. Would disconnecting and reconnecting the battery cause this. How long till it goes back to normal? 

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Do you notice it revving up higher when (casually) accelerating than what it did before you had the recall done? The ECM may have to "relearn" the most efficient CVT ratio at a given engine load and rpm. If it doesn't get better in the next couple tanks of gas I would take it back and complain. They may have to reflash the ECM.

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It seems to not have as much power as before like I need to give it more gas. Yes I know this car isn't really powerful to begin with but still. I'm taking a 1000 mile trip from Central Illinois to the Florida pan handle so hopefully it'll relearn the cvt by then. Idk. 

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On 8/8/2018 at 4:47 PM, silverspark78 said:

When I took my car in for maintenance work (17 spark lt cvt) they performed a recall 18089 which has some kind of programming I guess with the cvt. Ever since then the mpg average had gone gm down by maybe 5 or 6 from what I'm used to in the city. Would this update cause it. Would disconnecting and reconnecting the battery cause this. How long till it goes back to normal? 

 

Read more about recall 18089 at this link:

https://gm.oemdtc.com/8853/18089-service-update-tcm-obd-memory-diagnostic-2016-2018-chevrolet-spark

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Service Procedure

Note: Carefully read and follow the instructions below.

 
  • Ensure the programming tool is equipped with the latest software and is securely connected to the data link connector. If there is an interruption during programming, programming failure or control module damage may occur.
  • Stable battery voltage is critical during programming. Any fluctuation, spiking, over voltage or loss of voltage will interrupt programming. When required install the EL-49642 small-light.gif SPS Programming Support Tool to maintain system voltage. If not available, connect a fully charged 12 V jumper or booster pack small-light.gifdisconnected from the AC voltage supply. DO NOT connect a battery charger.
  • Turn OFF or disable systems that may put a load on the vehicles battery such as; interior lights, exterior lights (including daytime running lights), HVAC, radio, etc.
  • Clear DTCs after programming is complete. Clearing powertrain DTCs will set the Inspection/Maintenance (I/M) system status indicators to NO.
  • If the Same Calibration/Software Warning is noted on the SPS Controller screen, do NOT attempt to program the module. No further action is required. Refer to the Warranty section of the bulletin and use labor operation code 9102966, Module Programming Not Required.

Important: Before beginning the programming event, be sure the computer is connected to the MDI/MDI2 through a USB cable. DO NOT DOWNLOAD the files wirelessly or via Bluetooth connection.

  1. Reprogram the Transmission Control Module (TCM). Refer to Transmission Control Module Programming and Setup MR8 in SI.
    • The Transmission Fast Learn procedure is REQUIRED with this programming. If there is a pop-up in SPS indicating otherwise, ignore it and proceed with the Transmission Fast Learn as SI recommends.
  2. Record SPS Warranty Claim Code on job card for warranty transaction submission.

 

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There are a lot of steps for the technician to follow. These techs are known to make mistakes. If your Spark keeps giving you lower MPG (4-5 less is horribly bad) I would take it back to the dealer and complain vociferously. 

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