1,6 K4M VVT Problem (Hesitation when cold, loss of power)

[silencer51]

I also have a 1.6 Megane 11 on a 03 plate that is exhibiting similar problems, but this is coupled with a tendancy to stall after about 10 seconds. Starts again ok but does the same untill engine has warmed up. During this period it has the hesitation at low revs and in morning traffic progress can be a bit jerky - not a pleasant experience.

Problem suddenly appeared at end of September after car was parked up during my annual holiday, a few days later the Service light and engine management light came on. As car is out of warranty had the fault code read in my local (not Renault) garage, they said it was Camshaft position sensor, or possibly - but less likely - the dephaser solenoid. Both were changed and fault code was cleared. I now have no warning lights showing but the stalling and hesitation remains.

I found this website in my desperation for help as Renault say they can do nothing until I spend £65 on a Clip test with them - but if there is no fault code to read, what is the point??

Now I find this website full of other owners with a similar "undetectable" and "unresolvable" problem. Can any one help ???

I managed to get the dephaser changed in June under the warranty, it only had days to run, after complaining about strange noises and poor performance for some time, after this it was going well - but no more.

I have also had to have an ignition coil changed, my front discs squeal constantly, the back ones and pads were replaced as they had corroded badly - all seem to be common complaints on this site.

Someone must know something!!!

So, let me get this straight - you had the dephaser pulley, camshaft position sensor & solenoid replaced, but the cold start hesitation persists?

That's bad news for me...

[silencer51]

Indeed it does!

I got the hesitation yesterday and today when the car had been parked for almost 15 hours...

No strange noises, drives normally when warmed up, normal fuel consumption etc.

But after you turn on the engine and pull away after it has been parked for some time, it feels sluggish and has a couple of flat spots... After 2-3 minutes, all is ok.

Now, I know the pulley was replaced, I saw it with my own eyes.

Also I know it was replaced properly, or else the car would run like sh!te!

So, what's the problem!? 16 people have voted, 'Yes! I have said problem!" so far, has no one come to a solution?

Also, I don't know if it matters or not, but ever since I had the dephaser replaced, whenever I start the car from cold, the engine turns over 2-3 times before it starts and then it does so very hesitantly.

Before, the engine started really 'violently', even from cold - you pressed 'Start', the steering wheel unlocked, the engine turned over once and 'vroom' it hit 1200 rpm before idling.

Now it takes 2-3 turns and then simply the rpm go up to idle...

Should I be worried?

[Mick]

Yep, you get used to the problem, I've had the dephaser spring and oil activation valve replaced and the engine management upgraded on my 04 Plate 1.6 VVT Dynamic. These fixes improved the car but not eliminated the problem, I suspect it's related to engine management and the air mass control possibly not receiving the correct temperature sensor input.PS This car currently is giving 42 MPG in mixed motoring

[silencer51]

Mick, did they also replace the pulley?

[Mick]

Hi Silencer51, I do'nt know if the pulley was replaced, the chief tech said a kit of parts arrived with instructions in French (in Jan 2005) which he had difficulty in understanding and fitting the spring was a pain !! Is it important that the pulley is changed as well ?

[silencer51]

If by 'spring' he means the pulley, then yes, it requires lifting the engine, removing belts and tensioners etc.

There is no other 'spring' I can think of...

And about the instructions - technical bulletin 4432A is translated before being handed out to the dealerships...

[soterman]

At last, my quest has ended! Less than 20 days before my 2 year warranty expires, I had my dephaser pulley, camshaft sensor, tensioners replaced earlier this week. Reprogramming of the ECU was done as well (required) and the best part is that all that was FOC!

The results are absolutely magnificent! No hesitation at 1500rpm in the morning, no power loss between 1500 and 2500 rpm, it feels like I am driving another car! Also, consumption never went more than 10.2lt/100km (27.69mpg) when I was stuck in traffic with the AC on for 3 hours. And the engine noise is less in high revs, especially when you take your foot off the throttle, the noise is 'softer'.

[silencer51]

I replaced the MAT sensor a couple of days ago, didn't make a difference either...

I'm running out of things to replace!

Could it be a faulty oxygen sensor? I've done a couple of emmissions test and they came out perfect...

Also as I said there are no fault codes stored in the ECU...

The last few days its gotten really, really cold here (around 0 degrees)... Problem is more pronounced, i.e.:

I start the car, starts up fine, revs fine, rock steady idle, I unpark, set off with 1st and 2nd up to 3000 rpm, all is well, 20 meters later I reach an intersection and stop to look, as I take off in 1st again I feel a power drop at about 2000-2500 rpm, like someone's taken my foot off the throttle... This was very noticeable, passengers asked me what was wrong... For the next 5-6 minutes, until the engine temp gauge reaches 1/4 of it's travel I felt 2-3 almost unnoticeable flat spots (power losses) under 3000 rpm...

Tommorow I will be replacing the camshaft position sensor... Could it be dirty? Is it affected by the temperature? Could this be a throttle valve problem? Why does the car run perfectly when hot but has these problems when cold? I'm going insane!!!!

[silencer51]

To answer my own questions again, no, the new TDC sensor did not make any difference at all...

Can anyone recommend a good automotive engineering forum?

[IainMW]

Have you tried posting on the forum at Parkers?
https://www.parkers.co.uk/advice/forum/

[silencer51]

Yes, I also post at Parkers, however I am looking for a more technically oriented forum...

[meganeboy]

Silencer51,

How long did you have the hesitation problem before the pulley was replaced? If it took some time to change, then the Oxygen sensor MAY have been damaged.

If the hesitation is pronounced, then I suggest you take the car to the dealership, leave there overnight and have them drive it, with yourself with them to tell them what to do to replicate the problem.

[silencer51]

I have had the hesitation problem when cold for almost 2 years (maybe more), but didn't pay much attention to it (stupid, I know).

As I said, when the car has been warmed up it drives fine and accelarates from 700 rpm to the limiter with no flat spots or interruptions whatsoever.

The hesitation is more pronounced because the weather here has become, rather surprisingly, very, very cold (especially for November).

I plan on visiting my dealer next week and leaving the car overnight.

However knowing my luck, the weather on the next morning will be hot and the mechanic won't notice the problem (this is what usually happens anyway).

Also, the parking lot where they place the cars at the dealer is not ideal for experimenting and by the time they have gotten to the main street the problem might not be showing (car has been warmed up)...

But it really strikes me as very odd - 2 dephaser pulleys and exactly the same symptoms? What I mean is, ok, let's say the 2nd pulley is defective, that might happen once in 10000 cases. But for it to have the exact same symptoms, well, that is really, really weird... No stalling, no erratic idle, no noises etc. when starting up the engine, no diesel-like sound... I'm stumped!

[silencer51]

As for the oxygen sensor, well, if it was damaged, shouldn't the ECU log a fault? Modern cars monitor emissions very thoroughly and at the slightest problem the "Engine" light at the dash should come on...

[meganeboy]

As for the oxygen sensor, well, if it was damaged, shouldn't the ECU log a fault? Modern cars monitor emissions very thoroughly and at the slightest problem the "Engine" light at the dash should come on...

Most of the times, the oxygen sensor won't light any in the dash. I have a collegue with a Megane Classis (old model) who had to replace the oxygen sensor and didn;t have any lights, etc.... only sluggish performance (car is a 1.9tDI)

Most probabbly, the light will only appear if the oxygen sensor has failed completely, and not if it's operation is erratic. The ECU will not monitor if it is reading values correctly, only if it is sending or not.

Is your car still under warranty?