98 Megane Judder!

[3Piece]

Hello People

This is my first post, hope someone out there can help!

I have a 98 1.6 megane RXE which has developed a judder that can be quite violent and seems to occur mostly upon acceleration. I initially tried the obvious, changing plugs, checking air filter, changing HT leads, checking and changing igition coils. I was then advised to check the small hose from the MAP sensor to the inlet manifold which is prone to cracking, but it's fine. Still the problem remained

The car then broke down, upon recovery by the RAC I was told by the RAC man that the exhaust may be blocked - I had a complete new exhaust including cat about six months previous, so I took it back to Kwik-Fit who refitted the whole thing as part of their company policy - but still the problem remained.

However, they did point out that the exhaust manifold was now cracked in three places - so what I am asking is does anyone know if this will be the cause of the judder? I've already thrown some money at this problem and am reluctant to throw too much more at it unless I know that is likely to be the cause. Will the cracked exhaust manifold be the problem?

The car has also become extremely dodgy on cold starts! - starts ok but if you touch the accelerator it dies.

Can anyone shed any light on this for me? Any help would be greatly appreciated.

[rolphy1975]

hi, i have had a little browse on the net about manifolds but in the short time i was looking i didnt find out to much to say if it would cause a judder, sorry.

what i can tell you as to the starting issue is that the megane are prone to the water temp sensor playing up. if these go wrong they dont tell your ECU to alter its settings to what would in effect be like using a manual choke, i suppose this could also cause the judder you describe,

the sensor is on the thermostat housing usually under the temperature gauge sensor. these cost around £20.00 i think and are relatively easy for a diy job.

Also, the TDC or crank speed sensor may be acting up. remove it and give it a clean using a contact cleaner or WD40 type spray, the sensor is located ontop of the bellhousing and is held in place by two bolts and is kind of horse shoe shaped with two wires going into a connector block. these sensors are about £20.00 to replace , i cleaned my one up and it solved the starting issues i had but i still bought a new one and kept the old as a spare!!!

hope this is of some help to you, Neil

[rolphy1975]

hi, me again.

upon further web research i found out that the manifold could possibly cause the judder, but still worth trying my other options first maybe. especially for the cold starting issues, which may in turn solve the judder before replacing the manifold. sometimes when the manifold gets hot it will seal itself with expansion but should still be repaired at some point due to exhaust gasses leaking etc etc

[3Piece]

Hi Neil

Cheers for your thouhts fella - I've tried a couple of forums, and nobody has suggested these sensors yet - I'll give them a try before going down the manifold route, although as you say, it needs doing anyway if it's cracked.

Thanks again mate.

[rolphy1975]

let us know how you get on with the car if you change the sensors over.
A friend of mine had the cold start problem on a 2000 megane 1.6 where it would start but as soon as the throttle was touched it died on him, that turned out to be the water temp sensor and after some thinking about i did have the problem of juddering on acceleration and also a random issue with starting ( cold or warm ) when sometimes it would turn over and over and over and not fire and at other times it would start fine but be very juddery. this was sorted by cleaning then re-newing the TDC sensor , so you never know but you may just have the same probs with your car,

good luck with it