Reading fault codes on a Renault Megane 1

Tican

Tican

Tican

Soldato
Joined
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Leicester
Hi there,

Picked up a cheap 1998 Renault Megane 1.6 Sport, which has an engine light on,

unled2dkq.jpg
(sorry for the blurred picture)

It runs rough (won't idle)/smokey (not oil or water smoke, more running rich) until the light comes on, then it runs fine? Pulls well throughout the gears etc. :confused: The light will come on as soon as it hits around 4k revs.

Could a crankshaft sensor cause this? Or should I bite the bullet and get the code read for £50? :( Or is there a way I can read it myself?

Thanks in advance,
 
That used to come on occasionally on our Scenic. No idea what it meant and there was nothing wrong.

Check the air filter first. Ours used to have trouble idling on first start-up because the air filter used to get completely blocked. It was only a problem near the end because the screws in the air box all stripped and I couldn't change the filter :p
 
Jonny69 said:
That used to come on occasionally on our Scenic. No idea what it meant and there was nothing wrong.

Check the air filter first. Ours used to have trouble idling on first start-up because the air filter used to get completely blocked. It was only a problem near the end because the screws in the air box all stripped and I couldn't change the filter :p
Click to expand...

It might be the issue!

Tried to get the air box off, and one of the screw heads is very rusty, and I cannot get it off. Just waiting for my drill to charge :)
 
if above doesnt work check idle control valve, big problem on renaults of that age.

willb e on manifold and look liek this
clean with lots of carb cleaner
tn_iacv.jpg
 
Tican said:
It runs rough (won't idle)/smokey (not oil or water smoke, more running rich) until the light comes on, then it runs fine? Pulls well throughout the gears etc. :confused:

,
Click to expand...


There is a faulty sensor on the car, when the car is running rough the ecu is trusting that sensors readings and is using them to run albeit badly, then once you reach a certain rev point it figures out that the reading from the sensor cant be right so it ignores it, this puts the car into a 'run-home'* mode and puts the engine light on, the car will run better as it will use a pre-set in parameters reading but it will be slightly down on the power it should have.


*on older cars the run home mode often barely made a difference to how a car drove, its only been in more recent years that the car will have a hard speed limit or severely reduced power to force the driver into a garage.


Many issues can cause this so it will be easier to get the error code read.

A crankshaft sensor is possible but more likely to cause cut-outs, a idle air control valve wont really have any effect on the car when driving and shouldn't cause smoke, its very unusual for a air filter to cause running issues as well, normally just a drop off of power.

If you having black smoke then i would normally suspect MAF, MAP or EGR if fitted. Coolant temp sensor can also cause the same issues.
 
Thanks guys, I guess I will have to get it read at £50! About 1/4 of what I paid for the car! :(
 
dalin80 said:
There is a faulty sensor on the car, when the car is running rough the ecu is trusting that sensors readings and is using them to run albeit badly, then once you reach a certain rev point it figures out that the reading from the sensor cant be right so it ignores it, this puts the car into a 'run-home'* mode and puts the engine light on, the car will run better as it will use a pre-set in parameters reading but it will be slightly down on the power it should have.


*on older cars the run home mode often barely made a difference to how a car drove, its only been in more recent years that the car will have a hard speed limit or severely reduced power to force the driver into a garage.


Many issues can cause this so it will be easier to get the error code read.

A crankshaft sensor is possible but more likely to cause cut-outs, a idle air control valve wont really have any effect on the car when driving and shouldn't cause smoke, its very unusual for a air filter to cause running issues as well, normally just a drop off of power.

If you having black smoke then i would normally suspect MAF, MAP or EGR if fitted. Coolant temp sensor can also cause the same issues.
Click to expand...

I unplugged the MAF and it was still the same - then re-plugged it back in and it, again, was still the same.

Would I be correct in assuming it may be this?

Might take it off anyway and clean with some carb cleaner :)
 
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