throttle actuator

[djjayblue]

hello, i have 1.4 megane 03 had message about check injection changed spark plugs no joy i went to a local garage done i digonostic P0638 throttle actuator control , none of mechanics no what it is, do any of you know what the thing is for a start, and maybe how i got about sorting it. and what part i need to sort this problem

thanks alot

[davelowe]

The throttle actuator is probably the electric motor that moves the butterfly valve open and closed. There isn't (according to my manual) a cable that links the pedal to the butterfly valve - instead there is a throttle potentiometer. The fault P0638 is generated when the ECU compares the position of the pedal to how open the butterfly valve is, and the two don't match up within the given tolerances.

Logic would dictate that either
a) The throttle potentiometer is faulty (should be 5V and resistance 1000 +/- 250 ohms). Measure and if required, replace.
b) The throttle body is partially blocked by soot, so that the actuator is unable to achieve the desired position. Solution: clean the body.
c) Wiring or ECU is at fault. Check the wiring to the throttle body assembly.
d) Something else ie the actuator may be buggered. Replace it.

[lee1981]

hi, did you manage to sort this problem?? cheers

[lefterd]

I have a 1.4 03 megane.I am no way a guru car mechanic but using a bit of brain hopefully I sorted out the problem.My car was running a bit slow and sometimes cutting out when started.I had the throttle body cleaned and air filter replaced at my local garage.the air filter was clogged.After this my car started showing "check injection" and acceleration burst like a Ferrari.It was happening when engine temp gauge was half way up to the normal engine temp mostly when I needed torque(up hill or other situation).Car went to Renault manchester.No faults found, no idea what it was.Local garage scratching head.Then I read through Haynes manual and I started to understand a bit how it works.the throttle butterfly is not moved mechanically by cable but by a actuator/sensor so I thought that if the throttle is stiff, the actuator will not move the butterfly properly hence the problems.So I had a look at the butterfly hinge located on the right hand side of the throttle body near to the air filter.with the engine idling I tried to move the butterfly through the ginge by pushing with something(screwdriver,whatever).noticed that the hinge was greasy, dusty, dirty and difficult to move.than i understood.when engine was half hot, probably was melting the grease and dirt and butterfly was suddenly opening generating the burst of power and obviously over emissions.so i followed Haynes manual for reteaching the ECU the car running parameters.I have disconnected the battery negative lead.I have sprayed the butterfly hinge with WD40, using the straw to point accurately, on all the sides I could get to.left it for 2 hours with battery disconnected.than I reconnected the battery, started the car, held the accelerator to a rev very close to idle speed(800-1000rpm) until the engine warmed up and reached the normal running temp(which is the vertical gradation on the engine temp gauge), then held the revs up to 1200rpm for 2 min, than drove around town for about 5 miles(which involves breaking, accelerating,etc so the ECU learns your driving style).the car respods faster to acceleration and hopefully the check injection will be gone.best of luck.

[davelowe]

Excellent post. Someone should sticky it.

[Bundle]

great! i will try this..
is there an image or similar stuff for locating the throtle body and that hinge?

[MéganeDynamique]

Did this cure your CHECK INJECTION fault after all?

I have exacly the same thing. My 2.0 VVT is uncontrollable - feels like a Renaultsport version, the accelerator responds to the slightest touch. I have SERV + CHECK INJECTION + Engine Management Light. It's not starting well at all, needs a bit of encouragement.

[Wudby]

I've got a 1.6 16v megane on a 53 plate and I was
Getting the check injection and service light every 100 yards unless I was on the motorway then the car was fine but as soon as I was in traffic check injection limp mode after several attempts at cleaning the throttle body it was still there I've since then n at considerable expense changed the dephaser pulley, timing belt and it still did it however today I av changed the spark plugs , oil and oil filter and as such it as not done it again I will let u no if it as cured it or not.

[juddadredd]

Hi all,

Has anyone fixed this problem yet? I have a 2lt 16v petrol 54 plate.

I just had my throttle thing (big black box potentiometer) £140 as the mechanics fault reader said throttle problem replace the pot.
Rerplaced all of the coils with a spare Coil, and all four plugs, checkjed Air Filter.
Mechanic friend of mine checked throttle body, and sensors.

The car is great then check injectors comes on and it then goes to sh*t, stutters in low gears, and goes in to limp home mode.

Put it on a second persons analysis and it now says coolent temp sensor is -40, cleaned the sensor off as it was covered with gunk and refitted it until I can get a new one on monday.
I've spent well over £1,000 on it as had to have disks pads and a caliper change this month.

So please ANY help would be great, cheers Lee

[davelowe]

Lee, I replied in your duplicate post.