Vibrating enine

[AlexB]

The EGR valve, if stuck open, causes slightly uneven idle and reduces the flat out power. In mid range it is supposed to be open. If the engine vibrates at idle and does 0 to 60 in less than 8 seconds without passengers, then clean it.

The mount point, if not collapsed completely, should be doing its job, unless it was badly mistreated during the job of replacing the cambelt. It's quite possible, BTW. Check if it is installed exactly on its initial imprint in the paint. Check the fasteners as well.

Regarding the Italian tuning. It seems that if driven slowly and for short distances, the injectors become soiled in some sense. I have already written a review of injector cleaners. Believe me, Redex is not what you want to use... Try Comma Diesel Detox, which is a large bottle. More importantly, burn at least 20 litres of fuel at high load and high revs in one go to make it work. For this, you will need to brake whenever is safe and then accelerate flat out. Full throttle is important, as it opens the injectors.

I had the engine vibration after my wife was using the car for several weeks and I was away. When I returned, the comp was showing 12mph average. The Italian method resolved the problem.

I did put a full bottle of Redex diesel treatment in and it does run smoother but still vibrating on tickover so this does point me to the top engine mount.
Only had the car for 3 weeks so regarding the EGR valve,I'm not sure when it's been cleaned,
As it runs so smooth and picks up speed so quick I imagine the valve's ok

[marcuscolly]

Iv got a 2004 1.6 vvt and had the dogbone mount replaced and the top mount near the washer bottle, but when sitting in traffic it shudders and vibrates the car.

Any ideas?

[bbstoke]

Thanks Alex B. Will try that.
What is wrong with Redex? And where do you get Comma from, Halfords?
Cambelt was changed before I bought it so will check that mount.
Yes it does vibrate then fly off to 60 in 8 seconds,gets up to 100 quite quick too. (On the track, for legal reasons )

When you say "Full throttle" Do you mean red line it through each gear, or just push it to around 5000 revs?
Going to try this later today (Quite looking forward to it ).
Oh yes, "High load" ?
How much of the treatment do you put in?
Sorry for being thick,want to get this right and report a success.

Thanks for your help
Steve

[AlexB]

If it still vibrates under such an acceleration, then it might be not what I thought it was... Look at the engine mount or something else.

I thought the vibration was only taking place at idle, which can be explained by uneven burning in cylinders under extremely low fuel flow. Apparently, it is not the case.

Regarding "full throttle"... It is probably not relevant now. I meant getting the maximum rail pressure (1200 or 1400 bar depending on the pump type) and then opening the injectors full. You get this when accelerating with the pedal to the floor at 4000-4500rpm. There is a limiter somewhere above 4500rpm. In my understanding a combination of high pressure, high flow, high temperature and detergents might clean the injectors. This is assuming that they need cleaning...

Regarding Redex - all these small bottles mainly contain cetane improver (for an instant temporary "fix") and do not have much of cleaning and water removing properties. Therefore, they help only if one uses very low quality fuels. Comma Diesel Detox, however, contains plenty of detergents in addition to the winter additive, i.e. the good stuff which makes the difference between the basic and premium fuel. At some point I dug out the documents on the chemical content of these additives. Only Comma, Motul and AMSOIL appeared to have a more complex formulation than just a little of kerosene, cetane improver and dye.

...Yes it does vibrate then fly off to 60 in 8 seconds...

[bbstoke]

Hi, yes sorry it is only on idle that it vibrates,apologies Popped into Halfords today but they didn't have any D-TOX,but they did have Comma diesel magic,so I bought that then took it for a blast.
Didn't really knew it went that well,put the fuel and then the additive in and pushed it hard for around 10 miles.
Reset the MPG gauge and even with my foot down still managed 30 MPG
Really felt well under pressure, coming back on a slow road I had 60 MPG out of it.

When I hit traffic though it was still vibrating at idle only.
Have ordered some D-TOX online so will put that in when I've used this fuel up.
Mount looked in the right place but just from looking couldn't see any collapse of it.
Think this is the case and at £45 for the mount I will get that done.
Must admit though the car is better after that treatment and blast.

Thanks
Steve

[hardcore]

Mine had less than 50k miles on it when my mount was diagnosed as collapsed, i never even would have noticed until i seen the new mount(still use the old one as a weight for the lid of my recycling box), Renault told me it is a common problem with the megane, that website also told me the same, i actually replaced all 3 mounts but to be honest the other two were probably ok. By the way i didn't put the febi mount in mine it was by Birth but done the job , renault were looking £200 for part and labour which was absolutely ridiculous, took me 45 mins to do it and in fact it was one of the easiest jobs on the megane i've done to date.

[bbstoke]

Hi. Yes I was looking at the Birth product as it's cheaper,thanks for the recommend,will get that one now.
Just to ask,your car was vibrating when cold,did it get slightly better when you had been driving for a while,
even though it's still there?
Mine's terrible first thing,never goes away but does get slightly better when hot
Regards

[hardcore]

Yeah, mine is still like that when it's cold, but when it's warm it's fine but before i replaced mount it was vibrating also when warm.

[bbstoke]

So frustrating when you can't get to the bottom of it.
Thanks for the reply

[AlexB]

Comma Diesel Magic has a tiny amount of the same good stuff as in Comma Diesel Detox diluted in kerosene. It was probably designed to be 10% of the Detox price, but it is not... As you had to order online, why didn't you choose Amsoil?
https://www.performanceoilsltd.co.uk/die ... trate.html

Anyway, one needs to do more than 10 miles before the effect becomes noticeable. I would be also tempted to clean the EGR valve, as the last update you wrote that this vibration only happens at idle. EGR affects idle, its well known. I clean the EGR valve every second year, which is easier than to wait until it fails completely and becomes stuck in the manifold.

[bbstoke]

I've booked it in to my mech friends for next friday to get the EGR cleaned. I know where it is and have a good idea how to do it, but darn't.
Must admit the vibration is slightly better.
I'll bang the D-TOX in when It comes and do the blast out again.
How many miles should you do thrashing it?

[AlexB]

How long is a piece of string?.. A hundred miles at least for a significant result. The problem is that this will not help, if something else is causing the trouble...

I've booked it in to my mech friends for next friday to get the EGR cleaned. I know where it is and have a good idea how to do it, but darn't.
Must admit the vibration is slightly better.
I'll bang the D-TOX in when It comes and do the blast out again.
How many miles should you do thrashing it?

[bbstoke]

Check injector light has come on this morning and went into limp mode. Stopped engine then restarted and all was fine. Took it for a blast pushing it to it's limit and runs like a dream again (weird). Wondered if this was linked to the vibrating engine as I first thought it was the engine mount.
Could be a blessing in disguise as I was about to purchase a mount so I'll see how it goes.
Was minus 4 this morning so also wondering if it could be glow pugs as well but started fine
Out at a 5am tomorrow again so I'll see if the same things happen (fingers crossed)
Did put my foot down this morning when engine was cold so it's probably my fault
Update tomorrow

[bbstoke]

Morning update
Car was fine this morning,think it was just some poo going through the injectors as I've put some d-tox in there