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2 Posts
Discussion Starter · #1 ·
For a while I have been facing the following problem:
When I start the car for the first time after it rested for some hours (whether it's hot/cold, winter/summer), in the first few seconds I have an oscillating idle that comes with strange noises (gallops) and beats as if I were listening to music with drums.
After these few seconds, everything returns to normal. Moreover, if I start the car after I drove some time with it, it starts without these symptoms. While driving, the car works very well.
I did a scanner test and saved some graphics where the RPM oscillations appear (minute 38..39) and also saved some graphics where other sensors oscillate at the same time. Maybe someone manages to understand what the problem is. I thought about glow plugs, battery,EGR but I am not sure..
I will try to record the noises inside if they sound good.
Last year I replaced all the filters, oil, timing belt, pump and thermostat. But the problem appeared before.
Thank you.
PS: The car is a Renault Megane 3 1.5 dci 110hp


3 Posts
I strongly suggest a trip to your Renault
My modus had a lumpy idle. Poor general overall performance.
Now it's perfect.
First thing I learn from the attractive lady
Taking my details, is that unless engine fault
Light is lit up all well with the ECU.
No fault found. I recall fault happened after
A cambelt
So they checked out valve timing test.
It was out.
Restoring it and all was well with engine running to perfection.

3 Posts
They fitted a new belt, and gassed up the air con.
Cost was £650.
I think £400 for belt. It was only a year old, but they fitted new, plus water pump as one of the pulleys is part of it.
Apparently if valve timing is out the EcU
Won,t show it.
My local garage kept insisting no4 cylinder had a misfire because of p034 or similar error code. But the genuine Rennault fault finder
Said otherwise.
My local garage changed the belt a year ago
At my request. I had only had the car a week
And because I was not familiar with it
Did not connect the lumpy idle with cam belt change.
I.have always done my own repairs but due to poor health now have to use a garage.
Can,t think how they could get it wrong.
Next job they said was to take off head!
So, if I had use Rennault I would have saved
A lot of money.

115 Posts
So a new timing belt fixed lumpy idle? 🤷‍♂️👌
Yeah, some garages sure love to learn and poke around with your money. Hard to find honest AND capable mechanics these days, no different here.

3 Posts
Indeed, I only recalled a few days ago,
How smooth the clutch was when I first bought the car.
The smoothness has returned the shuddering being caused
By engine misfire( lumpy idle,)
It was then I realised that it was after cambelt change the lumpy idle occurred

Now the modus is a different car the engine
Is very responsive and probably more economical.
I recall when building engines some years ago
That incorrect valve timing CAN result in
The inlet valve, s sucking in air when they should be shut thus affecting the idling.
My main warning was that error codes
From a garage computerised fault finder
Is next to useless unless it's the right type.
Thzt camtiming is not part of diagnostics.
So to let others know and stop wasting money

For me, the maindealer will get my custom
From now on.
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