Twingo 1.2 Dynamic over revving

[powermite]

Guys

the zig zag warning light is on and when I start the car the revs rise to 3000 and the car revs itself between 3000 and 3500 rpm and theres nothing you can do to stop it.
I plugged it in to a computer today and there were no trouble codes stored.Any ideas what it could be?

John

 

[oscar]

hello john. classic symptoms of a jammed idle control valve or hunting as the old timers call it, what to do is strip down the throttle body and give it a clean with some brake cleaner or engine degreaser and make sure the idle control valve is free from any gunk or 'stuff' we shall call it. make sure the butterfly valve moves without hesitation before you refit it john. this should sort your troubles out.

incase you are wondering how i came to this conclusion, these trouble codes only spring up if there is an electrical fault somewhere and wouldn't throw a fault code up if something was jammed open because to the ECU it would still be working! ECU's are pretty stupid like that. if it was your throttle potentiometer you'd know about it, you'd have the appropriate fault code and i'm assuming you can still rev it?

 

[Dubz]

This is exactly what my car did when my throttle body had water damage

 

[powermite]

Oscar
no I cant rev it when its misbehaving.Pressing accelerator doesn't do anything.
It seems worse when its warm.Once itcools right down its ok for a while.Then when you turn engine off and then try to restart,it starts playing,
Dubz,could be water,as most people ,weve had torrential rain here on the weekend and that's when it happened
thanks for your answers
John

 

[oscar]

John, that would indicate to me you're ECU is receiving the correct signals from your throttle potentiometer and that something in the throttle on the mechanical side is jammed. i would strongly urge you to check that the throttle body and idle control valve. on idle, the butterfly valve is fully closed (see below image)

the idle control valve opens and lets in the exact amount of air required to idle properly, this creates a proplem with the MAF sensor when it cannot close it, it will open the throttle butterfly to compensate and constantly go back and forth usually at least 800 rpm's over what it should, constantly repating or 'hunting' to find it's 7-800 rpm idle speed but it can't because the idle control valve is jammed open. this is always caused by oil vapour from the positive crankcase ventilation system creating a small thin layer of oil on the air intake and inlet manifold (including the throttle butterfly and idle control valve) so any dust that gets through the air filter (always will happen) it collects on the oil and over time will turn into what i can only describe as 'gunk', it's usually good practice to give it a clean every 50k miles or so.
for your reference incase you don't know where to locate the throttle body (butterfly valve), as a rule of thumb it's ALWAYS after the airbox hose towards the inlet manifold and it'll be right there

hope this helps john

 

[Dubz]

Oscar
no I cant rev it when its misbehaving.Pressing accelerator doesn't do anything.
It seems worse when its warm.Once itcools right down its ok for a while.Then when you turn engine off and then try to restart,it starts playing,
Dubz,could be water,as most people ,weve had torrential rain here on the weekend and that's when it happened
thanks for your answers
John

Exactly the same as what mine did. I'd get it down to the local Renault garage and get it sorted quickly.

 

[powermite]

ive got the new throttle body coming tomorrow. Is it just "plug and play" or does it need any setting up?
John

 

[oscar]

yeah john it's plug and play. did you clean the idle control valve first? i really was 98% sure it would be the idle control valve, i don't think it would have been the throttle body itself... so you may have just spent a fair few quid and will no doubt be left with the same problem when it costs you less than a fiver for some brake cleaner and a rag!

 

[powermite]

thanks for your helps guys,its all fixed.Throttle body was the problem

cheers

John

 

[singlespeed]

John. Seal the center section of your scuttle pannel. The failure of your TB was probably caused by water dripping onto it from the center of the scuttle which has caused isued on several 133's and some 1.2s

https://www.twingo133.net/general-twingo-renaultsport/leaking-scuttle-panel-t6539.htm

You don't need to take the panel off completely to seal it. just enough to get a squirt of sealant in:-
Remove the long rubber seal from the scuttle. Simply pulls upwards
Remove the three (T20 torq)screws that hold the scuttle panel down. One in the middle and one either end.
Gently lift the front edge of the plastic scuttle panel upwards, so it comes free from the fixed metal tray on the R/H side of the car.
You can probably now see the squashed foam seal on the end of the fixed tray,which isn't doing a good job of keeping the water out
Squirt some sealant allong the edge of the fixed tray.
Refit....

 

[powermite]

Great idea ,thanks for your advice
John

 

[oscar]

thanks for your helps guys,its all fixed.Throttle body was the problem

cheers

John

knew it i'll send you the bill through the post lol, glad it's all fixed and you're back on the road as normal!