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Technical Supremo, Platinum Member
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4,268 Posts
Discussion Starter · #1 ·
ok lets start from the beginning
when engine is warm the cams tap like mad from tickover to 2000rpm
could this be the type of oil or a sign that the oil pump is on it way out
next it keeps missing a beat well quite a lot of beats
in 1st it seems ok 2/3/4/5 gear it will hesitate very badly you have to take your foot off the throttle and apply power gently
also i noticed on tickover it misses a beat about every 2-3 secs
when it is ok not very often it runs fine with lots of power in fact you have to be care full as the power kicks in with a bang
Ron
 
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its a year 2000 alize 20lt 16v according to the bible its a JA1B engine
Ron
Its an F4R740 if it's a manual or 741 if it's an automatic. Your engine has Variable Valve Timing.

It might be a faulty pencil coil? They are wired in pairs so if you unplug one you disconnect the other one it's wired to as well.

So try disconnecting each petrol injector one at a time with the engine ticking over. If you disconnect one that makes no difference to the running of the engine you have isolated the faulty coil.
 

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Technical Supremo, Platinum Member
Joined
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4,268 Posts
Discussion Starter · #5 ·
Its an F4R740 if it's a manual or 741 if it's an automatic. Your engine has Variable Valve Timing.

It might be a faulty pencil coil? They are wired in pairs so if you unplug one you disconnect the other one it's wired to as well.

So try disconnecting each petrol injector one at a time with the engine ticking over. If you disconnect one that makes no difference to the running of the engine you have isolated the faulty coil.
thanks i will try that tomorrow and report back
any ideas on the tapping can it help with thicker oil or do you think the pump is on its way out if so is the pump driven via the cam belt or is it a remove the sump jobbie
Ron
 
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I doubt thicker oil will stop the tapping. If you have an oil pressure problem I would have thought the oil light would be coming on? The oil pump is in the sump.

It may just be a hydraulic tappet? so maybe use a flushing agent and an oil change might help?

Thought the problem more than likely lies with the de-phaser pulley on the end of inlet cam shaft which is part of the VVT system. If the engine is relatively quite until it warms up and then gets noisy I would say it's the de-phaser and a very common problem with the 1.8 F4P and 2.0 F4R engines which use exactly the same de-phaser and when the start to wear can make the car sound a bit like a diesel engine. The noise is far worse than it sounds.
 

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Premium Member
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24,215 Posts
ok lets start from the beginning
when engine is warm the cams tap like mad from tickover to 2000rpm
could this be the type of oil or a sign that the oil pump is on it way out
next it keeps missing a beat well quite a lot of beats
in 1st it seems ok 2/3/4/5 gear it will hesitate very badly you have to take your foot off the throttle and apply power gently
also i noticed on tickover it misses a beat about every 2-3 secs
when it is ok not very often it runs fine with lots of power in fact you have to be care full as the power kicks in with a bang
Ron
If the engine is of the VVTi type the above symproms are typical of a failed dephaser pulley.:)
 

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Technical Supremo, Platinum Member
Joined
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4,268 Posts
Discussion Starter · #8 ·
ok had a look around and a de-phaser pulley cost from £55-£152 now has this been done or can it be done fit a normal pulley and do away with the de-phaser pulley
i was looking at renewing the cam belt as well so i may as well do it all in one go and remove the sump to clean the oil pick up and clean inside the sump i may as well check the bearings while i am at it
Ron
 
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I wouldn''t have thought the misfire you have is related to the de-phaser?

To put a standard pulley on the inlet cam shaft means the end of the cam shaft would have to be faced down to length by some 6mm otherwise the inlet sprocket won't be in line with the exhaust sprocket.



On engines with out VVT both the cam shafts are the same length.

The VVT inlet cam shaft also has 2 sets of oil feed holes one up through the centre of retaining bolt and the oil seal also has a larger ID as the oil seal is made on the pulley and not the cam shaft. The oil is fed by the de-phaser solenoid near to the oil filler point and advances and retards the inlet cam shaft depending on the direction of flow of the oil. It's doesn't constantly vary the timing it's either on or off. The de-phaser on 1.8 & 2.0 engines have a locking pin inside so the engine starts at normal timing once the engine has warmed up the locking pin releases and allows the de phaser to advance by around 6mm and then the rattling starts if the unit is worn. It takes very little wear as well. The de-phaser will then advance the inlet timing. There could also be issues with oil leaking if fitting a standard pulley on to the inlet cam shaft.

I don’t personally believe that the performance is enhanced that greatly especially not in a full blown race car like the Scenic :d so have disabled the de-phaser on 2 cars so far.

IMO there is 2 ways to do it you either fit a standard 2.0 camshaft and sprocket and a smaller ID cam shaft oil seal. Though there are very few non VVT 2.0 F4R engines to get the parts from. The inlet and exhaust sprockets are the same width and diameter the VVT exhaust sprockets have a bonded rubber centre whilst the non VVT engines don’t. In the photo both sprockets are from F4R engines the non VVT sprocket is the same as used on the non VVT 1.4 K4J and 1.6 K4M engines. Though the smaller engines use a different design de-phaser which I don't know anything about.





On the left is a non VVT F4R inlet cam shaft and has a stud thread locked into it and has only 2 oil holes. On the right is a VVT F4R inlet cam shaft that has broken on the oil holes of which it has 4.



The way I have disabled de-phasers is to drill out the tamper proof M6 bolts and split the unit and turn 8 pins to be a tight fit into the de-phaser vane chambers. This means the oil can still circulate in the normal manner and you don't have the problem of sealing the end of the cam shaft and the de-phaser solenoid can also carry on working in the normal manner and you have a nice quite engine again.








 

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Technical Supremo, Platinum Member
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4,268 Posts
Discussion Starter · #10 ·
thanks for the detailed pictures locking the unit looks a much better idea and removes any future problems
just about to give it another oil change as this has happened since i changed the oil filter and oil and 15miles running last owner had not done it for some time
but as i want to have a look at the cam belt i may as well do the locking of the de-phaser. at the same time great idea should be a sticky
Ron
 
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I forgot to say that VVT and non VVT cylinder heads are also different as there are extra oil feed holes and the cylinder head cover and cylinder head have holes through them for the de-phaser solenoid.
 

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Technical Supremo, Platinum Member
Joined
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4,268 Posts
Discussion Starter · #12 ·
I forgot to say that VVT and non VVT cylinder heads are also different as there are extra oil feed holes and the cylinder head cover and cylinder head have holes through them for the de-phaser solenoid.
de-phaser solenoid can it get clogged with dirty oil and can it be cleaned just thinking out loud new oil moving a bit of dirt around and a slight clogging up of the oil ways

Ron
 

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Technical Supremo, Platinum Member
Joined
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4,268 Posts
Discussion Starter · #15 ·
unless i have an intermittent coil fault i removed one injector at a time and istantly the engine missed a beat or 6
any way i was revving the engine up and down from idle from the rear air box the engine would hesitate for 1 sec at the same time a wooooosh of air could be heard before the engine picked up it was as though some thing was holding back the air intake for that second
Ron

thinking more on the air thing its when you try to put in to much power that the missing happens then you have to lift your foot untill it stops before you can add power again slowly
Ron
 
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revving the engine up and down from idle from the rear air box the engine would hesitate for 1 sec at the same time a wooooosh of air could be heard before the engine picked up it was as though some thing was holding back the air intake for that second
That does sound strange ? I can't say I have noticed that before on 16v Scenic? can you locate where the noise comes from?
 

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Technical Supremo, Platinum Member
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4,268 Posts
Discussion Starter · #17 ·
That does sound strange ? I can't say I have noticed that before on 16v Scenic? can you locate where the noise comes from?
after the air filter at the throttle cable area
how does the rear section come off thinking i may have a blocked pipe or just a good clean out
any diagrammes around
Ron
 
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Maybe the the idle control valv on the drivers side of the air box but that really is a guess? If you had ab air leak then the engine would be overeving.

The whole of the air box can be removed other the the ICV the only other thing is the crank case breather hole that vents straight into the air box but there isn't a valve on that until around 2001 when the throttle body became fully motorised and there is no throttle cable.

It's a faf having to remove the air box and I've only ever taken them off when doing other work to the engine. Access is made easier removing the wiper arms and lower windscreen panel and the panel under neath that. As well as disconnecting the drivers side engine mount ( jack under the sump) and pulling the engine forward to get the air box out.
 

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Technical Supremo, Platinum Member
Joined
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4,268 Posts
Discussion Starter · #19 ·
i will remove the air filter and see if it still does it i have only just fitted a new filter so possible its that there was a small amount of oil just past the filter it does not smoke so maybe built up over time then check any pipes as you say see if they are blocked let you know what i find later today
Ron
 
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unless i have an intermittent coil fault i removed one injector at a time and istantly the engine missed a beat or 6
any way i was revving the engine up and down from idle from the rear air box the engine would hesitate for 1 sec at the same time a wooooosh of air could be heard before the engine picked up it was as though some thing was holding back the air intake for that second
Ron

thinking more on the air thing its when you try to put in to much power that the missing happens then you have to lift your foot untill it stops before you can add power again slowly
Ron
The wooosh you mention was there on my my old F4R 2.0 Scenic and is there on my newer F4R 2.0 Scenic.

It happens if you stamp your foot down on the accelerater a bit sharpish, a short delay-whoosh-then the engine revs. Once the revs are above idle, it responds quicker.
It is normal for the 'fly by wire' electrickery said one Renault tech, but that doesn't explain why it happened on my old Scenic as that was a cable throttle.

A bit like you, my engine is far from smooth. Hesitation between each gear and pulling away, unles you rev the engine and slip the clutch. Then when driving it feels like I'm being towed on a piece of elastic. A slight, but definate, forward and backwards sensation.
 
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