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I would need some help here.

Car: Clio 2, 2000, 1.2 58 Hp, gasoline, D7f, 8V, 90000 miles

The car has trouble starting when hot. It runs nicely and can drive it, until that happens: RPM go up in the middle of a drive to some mid level even if nothing is pressed, car looses power. If I try to accelerate rpm goes down and won't move even if I wait a minute. There isn't any shaking, it just doesn't have power. It won't shut down on it's own. After I turn it off and wait, start it again it works normally and I can drive. That happened 2 times recently.

Is that a misfire or not? What could it be? I don't know, I guess in case of misfire car would still run of few cylinders and have some power back after few seconds?

In the last 7000 miles I changed: ignition coil, oxygen sensor, spark plug wires, spark plugs, head gasket, oil, fuel pump, crankshaft position sensor, air filter. I recently removed, cleaned the throttle body completely with its sensors and tightened it enough to prevent vacuum leaks. That issue still happened. Rpm are a little too high at idle, not completely stable. It smells a bit of sulphur, but not a lot.

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    Not that I'd say run out and get a new one, but would suggest this might be a problem with the ECU. Considering you can shut it off an it will go back to right seems to indicate to me it's getting something screwed up and not allowing the engine to run properly. Commented Apr 19, 2023 at 14:17
  • I am unhealthy emotional attached to this car, the more I fix it the worse it gets.:) Could be ECU and wiring.
    – Alex J.
    Commented Apr 19, 2023 at 18:38

1 Answer 1

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You're not describing a misfire.

The weird driving, power and RPM symptoms that you mentioned can all be explained by a fault in the accelerator pedal position sensor or the wiring and connectors between the ECM and the accelerator pedal. A fault here should be accompanied by multiple fault codes, which you have not mentioned.

You should scan this car for codes before you do anything else. You have not said why you have replaced a multitude of parts or whether those part changes were an attempt to repair the current problem or to fix unrelated problems.

I'm not suggesting you run out and buy a new accelerator pedal assembly. Yours may be perfectly fine but the cable or connectors could have a fault. Methodical diagnosis is the only way to know for sure.

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  • Some of it were to fix specific problems, some of it were as preventive measure, because I want it to run nice and clean, take care of it. Some of it were hit and miss from my standpoint before head gasket replacement. Acceleration pedal will be looked into with wiring, although i find it odd that if I pressed it down there was lack of power. Code scanner then.
    – Alex J.
    Commented Apr 19, 2023 at 18:38
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    @AlexJ. The pedal module contains two variable resistors. When you press the pedal, the output of the two resistors should be about equal at all times. This is a safety feature to prevent extreme acceleration in the event of an electrical problem in the pedal. The ECU constantly checks the two resistors to make sure they are giving equal readings. If they do not, even for a moment, the car goes into limp-home mode. It increases the RPM above idle so you have at least a little power, but it ignores or greatly moderates other input from the pedal because it doesn't trust the pedal.
    – MTA
    Commented Apr 19, 2023 at 21:01
  • @MTA Do you know for a fact this car works this way? I have a 01 Ford that does not operate exactly as you describe. Rather, it has one variable position sensor and an idle validation switch. When the pedal is at the top of travel, it activates the IVS and the engine is limited to idle. The first step is to inspect the IVS for damage and contamination.
    – user71659
    Commented Apr 19, 2023 at 23:37
  • @user71659 Not for a fact, no. I don't have a wiring diagram for a Clio, but I found a replacement pedal assembly online. The assembly's appearance and the 6 contacts on the connector are suggestive of a 2-variable resistor arrangement. And that would explain the unusual symptoms.
    – MTA
    Commented Apr 20, 2023 at 2:01

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