DimiBre

Hi, i need help
I Have mazda 3 2.0 140hp

from time to time my gas pedal stops responding while driving,in that situatation i just press and release clutch or change gear and everything is fine again.
Also today on highway while cruise control was on, it just went off and gas pedal didnt respond, again i pressed and released clutch and everything is fine.

Michaelscot9

So I believe in 2008 the accelerator pedals were using an Accelerator Pedal Position sensor which uses two five volt reference signals to find a specific voltage to send to the throttle position actuator and throttle position sensor to correlate the throttle body butterfly valve to the appropriate position, if lacking throttle response, first make certain the throttle body is not functioning by removing the air intake and having somebody actuate the pedal. Look for sudden movements that don't correlate to pedal position, this is most easily done with a scan tool allowing you to observe engine data, and verifying that throttle position always corresponds to throttle accelerator pedal position. You should easily be able to log data while driving as the issue occurs, simply test drive with the tool logging the data and play back that data to verify that throttle position corresponds throughout the drive. If not then you'll likely see the issue as throttle position voltage and accelerator pedal position voltage fail to correspond, this could be due to either the throttle or the accelerator, see which one fails to send data and replace appropriately. If no scan tool is available and you're down to your eyes and a multi-meter, verify function as outlined before, if fault is noticed test the accelerator pedal position sensor as outlined in the repair manual (I've included the entire testing here, but you can scroll through simply to the harness connector view). Pierce the wires of pins 2 and then 6 against a ground while the ignition is on and verify that when pressing down on the accelerator pedal the multimeter reads from 5v to 1v and 1v to 5v respectively. If any abnormalities are notice replace the pedal, if everything looks well when repeated multiple times then replace the throttle position sensor. This is much easier to diagnose with a good scan tool. I personally recommend the ThinkDiag from ThinkTool, it's around $130 on amazon with a one year subscription and it's easily the best value tool I've ever used. I use it everyday as a professional mechanic and it easily rivals a $1000 Autel diag tablet and most $1500+ tool truck scan tools.

Michaelscot9

I went ahead and looked back through some old scan tool data and found a failure of an Accelerator Pedal position sensor that will cause this type of issue. I has two sensor to be redundant and more specific, when one fails you'll see erratic acceleration issues like you're describing. If you look at this Accelerator Pedal Position Sensor 1 in this graph, you can see that it doesn't correlate to Throttle Position Sensor 1, and is similar voltage to APPS 2 rather than being its inverse as it should be. If you look at scan tool data and see something like this you'll know that's your issue. Generally this will pop a CEL as DTC 2138, but if it's an intermittent issue it might not necessarily pop a code unless it occurs at least once per trip for 3 trips.