Scotty, MY wife's 2007 Mazda CX9 is hard to start on some mornings.
It has 3 issues; #1. Hard to start on some mornings. We have had to replace the battery once a year for the last 3 years, but the battery warranty has covered it at no cost. No one can diagnose any other issue - except for bad batteries from AdvanceAuto Parts. When I replace the battery, the car does the same thing after about 8 months with the new battery. It will crank, but will only start only after multiple tries at cranking. It seems to get plenty of power when cranking.

#2. When driving on the highway at 50 mph or more, when I take my foot off the gas, the car still continues on without slowing down, until I start braking. We have cleaned the throttlebody with Throttlebody cleaner (it was really dirty.) The issue still persists after cleaning. I have taken the car to a repair shop, but they just cleaned the throttlebody again, without any change in performance and they did not charge me.

I don't know if these issues are related or not....... It appears to idle fine, once started, but my BlueDriver Diagnostic tool is giving me information stating otherwise.... According to my BlueDriver diagnostic tool, there are NO codes.

#3. The BlueDriver "live" data while engine idle tells me: The Throttle Position Sensor (at idle) is at 19.6% and drops to 12.9% intermittently - all during idle in the driveway and without touching the gas pedal. This drop also corresponds with the reading of the Mass Air Flow Rate dropping from 3.58 to 3.43 g/s during idle. The RPM range is 612 - 629, once warmed up - but the intermittent changes in the TPS and MAF rate still occur.

The reading of the Relative Throttle Position is at 2.0% and does not change during idle. The Command Throttle Actuator is 3.5% and does not change during idle. Fuel Level Input is steady at 37.3%.

Your thoughts? Thanks, in advance, for your help. The parts are expensive, so I am trying to determine where to put my hard earned cash to fix the issue. Brian

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Scotty Kilmer
Scotty Kilmer

Editor

realize those are true junkers as they age. Don't put much into it. But knowing those, if it's a vvt engine, that system is breaking down. See it all the time.. More to fix than the vehicle is worth in most cases