Urgent Help - Renault Megane, 1.6 Energy Wont rev out

[Chris Hebden]

Hi all! I'm currently stuck at my Mrs house (luckily thats wear all my tools are!!)

My Megane (1997) wont rev out, it'll just about idle but as soon as you press the throttle the cars coughs and splutters until you either let off or the engine cuts out.

It used to do this when the car was driven straight off from warm but now i cant even get it to rev when the car is stood still.

I have quickly checked all the vac pipes i understood (which wasnt much) but cant find any that are leaking! Any other ideas i can check asap would be blooming marvellous!

Cheers Chris

[Spooky]

crank position sensor, idle speed control valve?

[Chris Hebden]

Would this stop it reving - cheeky ? Quick google search says it could be a TDC fault or a water temp sensor fault????

How can i check either of these?

[royz]

try unplugging the 2 sensers on the water pump as one tells the ecu the engine temp and could be causing the problem. on my missis old one it did the same when cold. chaged the sensor all was ok

[Chris Hebden]

try unplugging the 2 sensers on the water pump as one tells the ecu the engine temp and could be causing the problem. on my missis old one it did the same when cold. chaged the sensor all was ok

Nice one, thanks. I'll see what that does?

[Spooky]

Yea the water temp sensor maybe the culprit, might be worth unplugging as has been said.

I know on my 172 the same sensor made the limiter come in almost 1500rpm earlier than normal at high revs...

[royz]

hope it sorts it out.

[Chris Hebden]

Thought i was getting somewhere, removed the top (brown plug) and started the car, nothing changed. Removed bottom (white) plug with brown disconnected and the car would start first time but wouldnt idle nicely, instead the rev's would rise quite high so i cut the engine off.



Tried starting the car with just the brown connected and car wouldnt idle, so disconnected that one and reconnected just the white one and again, the car wouldnt idle. Which says to me it cant be either of these......................!?

[mike r5 gtt]

is it an 8valve?if it is there is a vac pipe that runs from the manifold to the map sensor (little black box by the n/s/f strut) the pipes split and cause this prob

[Tony Walker]

I agree map sensor and piping to it most common cause. is it idling high? if you have some brake cleaner spray around the inlet area if the engine rpm changes you have an air leak and should be able to pin point it.

[Chris Hebden]

Cheers guys, was going to do the brake cleaner/carb cleaner test!

Last night it started and idled fine, then i started taking the plugs off shown in the picture above, and only once did it idle really high! Then, wouldnt idle at all!

[Chris Hebden]

Ok, this morning wouldnt even start! Managed to get it to fire once but thats it. I am thinking a TDC sensor fault now. I have a spare renault 5 one lying around and wondered if i could temporary join the 5's sensor loom with the megane one.


Megane Loom (pink & light orange wires)


5 sensor loom, (red and white)


Sensors

Is it possible just to get it running by bridging the correct wires of the 5's wires with the megane loom? If so, which one are the right wires and can i do damage if i get them the wrong way round (i know you can change them on a 5, but is it the same on the Megane?)?

Cheers Chris

[Chris Hebden]

Well i gave the TDC idea a bash and no change! I went back to the MAP idea and tripple checked the pipe had no holes in, just to make sure i replaced it with some vac pipe i have and the car started and ran for 1 second and then died! Wont start again now ! Any ideas?

Could the MAP sensor be at fault? Is it back to coolant sensor fault? Can either of these be picked up with a fault code reader!?

Chris

[Chris Hebden]

OK my breakdown cover (through insurance) doesnt have anyone who can diagnose faults only take me to a garage and get them to do it!!! Gunna just have to start replacing parts i guess

[mike r5 gtt]

id say start with either the map sensor/piping or the idle valve.
have you tried taking off the air inlet pipe and cleanning the throttle body/butterfly??

have you got a renault minute dealer near you?only because they should offer a free fault check (on the basis they assume they will make there money back fixing it)!!so you could get a free fault check which should point you in the right direction!!!

[Matt@CodeRedMotorsports]

Cam timing ok?

[Chris Hebden]

I took off the idle control valve cleaned it (it was covered in crap) fitted it and the car started and idled but as soon as i throttled it the engine died. Tried to start it again and nothing.

Took off throttle body and stripped TPS and ICV cleaned it all off and refitted, made no difference.

Replaced vac pipe from manifold to MAP sensor and made no difference.

Checked spark and all is ok.

Should i be able to move the plunger for the ICV in and out with my hand?

Cam timing i can only presume everything is ok as there "should" be no reason why it had changed?

[Brigsy]

Check the fuel pump/filter mate, might be lack of flow?

[Chris Hebden]

Check the fuel pump/filter mate, might be lack of flow?

I can hear the pump priming as usual, cant test fuel pressure unfortunately. I am going to stick on a fuel filter, map sensor and idle control valve and see what happens!

[Chris Hebden]

Hay all! Time for an update! I have just come back from hols and fitted a new idle control vavle, map sensor, spark plugs and fuel filter and nothing has made a difference ! Still wont fire.

I am at a real loss now. All i can think that could need changing is the TDC sensor (but i have already wired a 5's one onto the megane to see) and a throttle body!

Can anyone else please give me some things to check! I cant check fuel pressure but the pump is spinning throughout cranking, there is spark on all four plugs and everything bar the TDC sensor has been changed!!!!

Cheers all

[Chris Hebden]

Could this be an earth fault? How could i rule an earth fault out?

[Chris Hebden]

Not sure if this is significant or not but i ended up having to jump start the car last night and when i had both leads on the donar cars battery and both leads on my battery terminals the car would crank nicely. As soon as i moved the earth lead from my earth terminal onto the engine or gearbox i would get a sparking, tried turning the car over and it wouldnt crank over very well, as though the battery is flat (which i know it is)!

Does this mean i have a broken earth somewhere as it'll crank when donars earth is put to the battery but not when its attached to the engine?!

Chris

[Chris Hebden]

Right quick re-cap:

1. Check earths - done
2. Check spark - done
3. Replace idle control valve - done
4. Replace MAP sensor - done
5. Replace Sparks - done
6. Replace fuel filter - done
7. Explain to Mr Bean AKA Pete that he is silly to suggest that i wouldnt have fuel in the car - done
8. Check to see if fuel is getting too the injector rail - done (no there isnt)
9. Check if there is fule coming out of the fuel filter when priming - done (no there isnt)
10. Pull out float sensor and pump - done
11. Inspect float chamber and pump - done all ok
12. Have a look into the tank too see the lovely amount of fuel...............................

No fuel stops a car from running !! Trusting a fuel gauge never a good idea...........! Put fuel into tank and car starts.....................