I was checking the CEL code on the Mystique today, and I got thoses with the KOER test :
116 - Engine coolant temperature higher or lower than expected
225 - Knock sensor fault during dynamic response test
Let me explain the situation : the car (95 Mystique 2.5 ATX) had an intermittent CEL for about 2 years before we were able to fix the problem - 2 bad oxygen sensors and a very badly clogged intake manifold. With that work done, the car ran a bit better, but at least didn't longer smell rotten eggs.
One thing that wasn't fixed was the engine hesitation between 1200 and 2500 RPM. the situation is pretty similar whenever the car is in Park on in Drive : it idle just fine at 750RPM, but when I hit the gas a bit, like 1/4th of the pedal, it start to misfire (or it looks like) at 1200-1500RPM and rev slower up to 2500RPM, when the engine gets back to normal and rev more freely. When it seems to misfire, you can hear some irregular air flow coming from the exhaust.
On the highway, it's pretty much the same, and you can feel the car jerk off when it hesitates.
Last week, I pulled the code and cleared the Continuous memory, and today it was empty - good thing.
I too cleaned the Intake manifold with a bottle of Air Intake cleaner, and after some black smoke a a black carbon spot on the ground near the exhaust was created, the car run a bit better, but still have misfires.
We run it on 91 gas for a year now, the car got better gas milleage and less hesitations with that, but after reading some posts about 87 vs 91 gas, I'm not sure if this wouldn't be the culrpit...
About the Coolant Temperature sensor, well the gauge seems to be pretty exact, is this the sensor that the Coolant gauge reading ?
The engine get a little knocking, just perceptible, could this be the cause of the code ?
Ohh... too, I would like to know if the spark plugs can ben easily changed on a 2.5, the seems to be pretty well hidden behind the Intake manifold. This is probably more difficult than on the Topaz, but that's the price to pay to have 170hp I guess hehe.
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