My 1990 (built in the summer of 1989) is having issues and I need help. After I reach operating temperature (and not before), my check engine light comes on when I decelerate. Now that it's been a week and I can't find a Mazda dealer with a rotary mechanic or a local shop to perform a profession diagnosis, the light is coming on at idle as well. The egine sounds like it's missing or hesitating at idle although acceleration is fine and performance when applying gas it's not an issue.

I have recently replaced the belts, plugs, O2 sensor, and performed a coolant flush. So, I'm usually really good about performing all of the necessary maintenance.

I may have a code 0012 engine code, but I'm not certain as I do not know whether to trust the source. If it is the TPS, then why is it only an issue when the car has reached temperature? Is this something that can be adjusted or should I be leaning more toward replacement? Could it possibly be the Coolant sensor/or temperature sensor? I had a Subaru before this that had similar issues and it was the O2 and coolant sensors.

Thoughts or advice?

 

Well, I followed someone's posting about taking the voltmeter to the TPS and testing the idle and full throttle ohms that the TSP is supposed to put out if it's reading correctly and amazingly enough....mine reads just fine. 1ohm and 4-6oms at idle and 4-6ohms for both green and orange at full throttle.

The backfiring upon decelleration is starting to get really bad (engine light still only comes on when not on the throttle). So it must be something having to do with the throttle plates or fuel cut. I keep reading things about the "DECELERATION CONTROL SYSTEM", what is this? I'm about to drive the car 3 hours to a better mazda dealership, but I don't want to get hosed or talked into replacing things that might not be wrong.

Plz help!

 

Okay, although my TPS was putting out the volts designated to be correct (mentioned above), I'm still getting code 12 and 18. Any thoughts on what or how else to test this crazy thing. It's beginning to drive me nuts.

Oh, I guess I forgot to ask...whether the two plugger TPS could actually read correct on the lower TPS (one with the green, orange, and black wires), while the upper or inner TPS (blue, red, and yellow wires) could be the one malfuntioning?

Please help, as I only have one more day before my trip.

 

what did they say?

 

No one has replied to this.....I figured that these forums would be a little more helpful. I'm taking it into another Mazda dealership on Thursday if I found out something that will help others...I'll post it here! Until then...if someone knows something....please share it.

 

first step is to find out exactly what codes are present and when...

try coasting down a long hill with the check wire grounded out. write down what code that is...

which code at idle? etc etc

if you find that out, we can go from there

 

What? I'm going to test the engine codes while that car is coasting down a hill? The code is always the same....12 TPS (FULL).

I have tested the front TPS with the GRB wires and do not have the information for testing the second TPS. But the front TPS reads the correct ohms at idle and full throttle. I performed the 2000 RPM gentle pressing of the TPS to see if the engine rpms increase, and the test light to make sure one light is lit, indicating that the TPS is adjusted properly...and all of those come back FINE!

Still code 12 (engine light) after it reaches full temp, only when I'm not accellerating.

I've ordered a new TPS dual plunger system for $112 straight from the manufacturer, but they say 3 weeks for the shipment and I'm still not 100% convinced that replacement is the solution.

P.S. If no one comes up with a better solution and replacing the TPS does work, I will post back for others with the same issues!