I've been having this problem for months now. The check engine light will come on intermittently (especially when I don't let the car warm up to normal operating temp-I mean the guage must be as high as it ever gets between hot and cold). Sometimes when it comes on nothing happens, but other times the engine seems to stumble and I have little if any power and the car is essentially not driveable. I pulled the engine codes and got the following:

-(8) Airflow Meter (AFM)
-(9) Water Thermosensor
-(10) Intake Air Thermosensor (AFM)
-(12) Throttle Sensor (full range)
-(18) Throttle Sensor (narrow range)

I can visually examine all of these components (except the water thermosensor which I think is on the water pump), but do not see any visual damage or wiring problems. I have checked resistance on the Airflow meter, and TPS, and they are both within specs. Does anyone have any ideas on what to check and how to go about finding the source(s) of these problems?

Thanks for any help,
Derek

 

the car will all of a sudden buck/ lose power when you're just cruising along if the water thermo sensor is bad, I accidentally broke the harness backshell on it when installing an alternator & didn't notice until I finally figured it out months later...about $45 from Mazda for the part. If not that, I dunno...

 

Thanks for the info. I've heard a lot of people say that the connector on the water thermo sensor is easily broken. I'll check it out this weekend. Any other comments on this or the other problems?

-Derek

 

your ECU pins are probably different from mine, but I would read the thermo sensor input voltages at the ECU while the engine's running/ accelerating to see if you can get it to "screw up"- that way you'll know that's the prob

 

your ECU pins are probably different from mine, but I would read the thermo sensor input voltages at the ECU while the engine's running/ accelerating to see if you can get it to "screw up"- that way you'll know that's the prob...Everytime my car gets problems (which is often), I go to those ECU inputs now- good way to troubleshoot...

 

Thanks, I'll try that.
By the way, I took the connections off of the TPS and AFM and cleaned and reconnected them, and I think they are fixed. I'm gonna disconnect the battery and recheck the engine codes the next time the check engine light comes on to see if I only get the water thermosensor code (9).

-Derek