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172 Phase 2 Throttle Problem

I think I have a problem with the throttle pedal/somewhere in the management system on my 172.

The car has only done 800 miles, the problem developed after a couple of hundred.

When cold (stone cold i.e. the first mile or so). The first few mm (past the usual bit of free play, that is) of throttle travel do nothing at all. Depress the pedal a bit more and the power comes in suddenly. At low speeds at very low throttle openings (say a steady 30mph, 3rd or 4th gear) the engine feels very nervous, as if someone is tap-dancing lightly on the pedal (sorry, can think of a better analagy).

Once the engine gets a bit of termperature into it everything smooths out nicely.

The only other thing I have noticed now I have finished the first 625 miles is that the last little bit of throttle pedal travel doesnt seem to do anything.

Apart from that the motor seems sweet. Fairly linear acceleration up to about 5,000, then a marked increase, harder note to the motor. Havent gone past 6,000 yet, and only use more than 4,000 occasionally - I want to let the motor bed in a little more first.

Any suggestions?
  Corsa 1.3 CDTI

I have this on mine. Its like the throttle is vibrating so the car is jolting along very lightly if that makes sense, but I put it down to a "TRAIT" of the car.
  Corsa 1.3 CDTI

Kinda, but its not as extreme. It takes about 3-4 minutes to cure itself but I dont really worry about it anymore. I used to think it was me but it appears not.
  Renault Laguna Coupe

Mines exactly the same. I think the ECU is doing something while it knows that the engine is cold. I get this every morning, and it clears at the same place.

the sensitivety of the throttle is slightly different until ECS reads normal (Engine coolant sensor)

However, it shouldnt do what yours does.

suggest they check the ECS as the first culprit, then the throttle pedal potentiometer.


Mine does the same thing, but only if the cars been left standing for at least half a day. I asked the workshop to check it twice, but they said everything checked out OK and their diagnostic computer didnt pick up any faults. Looks like its normal, seeing how many people have it.

Thanks everyone.

Captain - yep, Ill get it checked out. If its a fly-by-wire throttle I suppose the potentiometer could be faulty/dirty as you say (exactly the same as a dirty volume control in your hifi amp at home - crackle, crackle, BLAST!)
  VW Potato

mine too. every morning from cold, at about 2.5k it seems like its being restricted, a bit hesitant. then suddenly without applying any pressure on the accelerator, it seems to clear and the power is lovely and smooth.

If itd not damaging the engine, Id rather not let Renault try and fix it - it only last for about two minutes when stone cold, so hardly worth them cocking some thing else up to try and fix it.


I get the same to, it seams that it clears at about 2.500 rpm, I went down to our local renault garage, and spoke to the service manager and he said because of the tune of this type of motor you may experence lumpy running when it is cold this is because of the cold start programming in the the ecu.

Not just mine then,

It is a cold start issue and is even worse if U have the AC on at start up.

Does go after a mile or so.

Seems push the right pedal (not even hard) and nothing!!! Then a hauge surge of power that is unexpected to say the least. Like all or nothing.

Anyone find the answer, (and I will ask the dealer)let me know.

Didnt think I was that clumsy


Update after visit to dealer. Renault are aware of the problem but havent issued a software fix yet.

(For those in the IT world, this is exactly the opposite of the Microsoft system - they deny knowledge of ANY problems, but keep issuing fixes!)