Hey fam!
This is somewhat of a humdinger, as I have been going nuts trying to find the cause.
The Car:
2000 Mazda Protege LX
1.6L 4-cyl
5 Speed Manual Transmission
The Issue:
The car runs and drives beautifully when first started. The issue is that once the coolant temperature reaches 170F (op temp) and the ECU goes into closed loop, the engine has a super rough idle, is misfiring, and has a serious loss of power.
Helpful information:
What has been done so far:
Current Thoughts:
TLDR
My 2000 Mazda Protege operates great until it gets to exactly 170F (Closed Loop), at which time it idles super rough and has almost no power during acceleration. If driving when it hits this point, it bucks for a few seconds then goes to complete crap running.
This is somewhat of a humdinger, as I have been going nuts trying to find the cause.
The Car:
2000 Mazda Protege LX
1.6L 4-cyl
5 Speed Manual Transmission
The Issue:
The car runs and drives beautifully when first started. The issue is that once the coolant temperature reaches 170F (op temp) and the ECU goes into closed loop, the engine has a super rough idle, is misfiring, and has a serious loss of power.
Helpful information:
- As I said previously, everything is great until the car goes into closed loop operating mode at 170F. I have a OBD2 logging software that shows the RPM instability as soon as it hits 170F.
- Battery @ ~12.8v when engine off.
- Voltage drops down into the 11's while running, but when hooked to another car while running, voltage is stable > 12v and issue remains.
- Fuel trims are all over the place, I am not sure what they normally look like on this car but they bounce all over the place from -30 to 25.
- For a few seconds after hitting temp, it will buck a few times if driving (Power, no power, then power again, etc)
What has been done so far:
- Upstream O2 sensor replaced.
- MAF sensor replaced.
- New spark plugs
- New coils
- New plug wires
- New intake pipe
- New coolant temp sensor
- There are no vacuum leaks
- MAF (New)
- Upstream O2 (New)
- Compression (Tested)
- Plugs
- Wires
- Coils
Current Thoughts:
- It is definitely a thought of mine that the ECU could be bad. Not only is it only acting up at temp, which is when the ECU actually does real work, but my OBD2 sensor is seeing updates at random intervals. Sometimes the sensors will update every second, sometimes it takes 15 seconds to update. When it starts taking 15 seconds, it usually does this consecutively for a while. Sometimes the data sticks for 60 seconds.
- If not the ECU I am pretty positive that it is a sensor, as open loop before temp runs 100% fine.
- It's possible the crank position or cam position sensors are failing, I will test those with a multimeter today.
TLDR
My 2000 Mazda Protege operates great until it gets to exactly 170F (Closed Loop), at which time it idles super rough and has almost no power during acceleration. If driving when it hits this point, it bucks for a few seconds then goes to complete crap running.
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