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

[markren2004]

I may sound a but simple with this but i am kinda an old school engine fitter, (diesel). i have bought a 1.6 VVT meg2 on a 54 plate had the issue this forum mentions and thought instantly that the problem was ignition. i have replaced for my peace of mind the 4 coils 4 plugs and the HT leads. the problem seems to have cured itself. my plugs were worn (electrodes worn).
the last car i drove with a petrol engine was a 1990 ford(wont say what) but had the same problem with starting. easy engine on ford, 1 coil 1 distributor 1 LT Lead and 4 HT leads.

should of mentioned my 4 coils and sparkplugs are less than 9 months old (and a recent cam sensor)...so can't see it been those. as i say the only think thats changed recently is the dephaser...can anyone confirm or deny if the megane needs an ECU software update when a depahser is changed ?

[silencer51]

Guys, the dephaser pulley alone apparently does not cure all hesitation problems.

I have looked at this morning start hesitation problem extensively and I have gotten nowhere.

My car always starts up fine no matter what, does not produce weird sounds and generally runs fine. But on every cold start for the first hundred meters the car feels sluggish and there are noticeable flat spots and generally unpleasant engine behaviour until it starts to warm up.

Replaced dephaser pulley and solenoid, replaced every imaginable engine sensor except O2 sensors, replaced throttle body, new sparks, new coils, etc. nothing has fixed that, I have literally tried everything, it seems for some cars its a characteristic.

After the temp needle starts to move the problem dissappears, and sometimes it's almost non-existant from the very start. Very weird.

It could be an ECU problem, but my ECU has already been upgraded once (to version 7.74) and the CLIP diagnostic reports it as 'locked - cannot be flashed again', so I can't try a newer firmware...

So I just live with it until I can buy something better.

[Rallye Sport]

The car is off to the garage tomorrow night so they can experience it first thing Tuesday morning. I can't believe that this problem has been known for so many years with everyone on this forum and I'm guessing Renault and yet its not been worked out. I so wished I had read up on this forum before buying the car! Lol

[AliasOmega]

I know im new to the forum, but before i bought the 1.6 VVT Megane, I had a 2004 2.0ltr Clio 182.

When it was cold outside, the car started from a cold start (usually left for 8hrs) would judder & hesitate to drive from cold, if you held the revs at that point you could feel the power loss at that RPM, then as the car warmed up more (30secs later) you could feel the surge as the power came in, until it warmed up again. It was not very often.

We put this down to the ECU protecting the engine from being red-lined from a cold start, and using the exhaust sensors to monitor engine temp through emissions.

The next time you started it, usually at 3am (about 2 degrees in the uk), it would be fine.

[Rallye Sport]

the car was back in last week 2 visits as usual as the car working fine the first time apparently. They sorted the window reg on warrenty which was nice. They put it down to the Bosche spark plugs that were fitted, they said it was better once they had fitted standard ones. It was fine Monday morning but this morning it was back to it's usual self. So looks like I'll be booking it back in this week. Is there anything I can tell them as I cannot believe Reno does not know of this fault! Otherwise I think I may sell it, as I'm fed up of trips to the garage. any help appreciated, Thanks jamie

[Mick]

Hi Jamie
I found this post which might give you some hope, it seems that someone got a special software upgrade from Renault which resolved the problem that you and quite a few others are encountering.
viewtopic.php?f=2&t=6684&p=46754&hilit=bournemouth#p46754
Regards
Mick

[Rallye Sport]

latest update .........they swapped the throttle body over with another megane and it still did it so they ruled that out. They have checked all sensors and ruled them out too. Ecu was upgraded when it had new dephaser fitted. They have said that the problem is down to the valves opening incorrectly and that it is an electrical fault either with the wiring or the Ecu itself. I've lost my patience with it for now so I'm gonna live with it for now and they are gonna take a look at it in the new year when I have some spare cash to throw at it! They said they may find it in 20 mins but it could be as bad as needing a brand new Ecu!

[silencer51]

@RallySport: can you tell your garage to flash the ECU to the latest firmware?

The problem with Renault's idiotic ECU flashing system is that apparently every ECU can be flashed only once, and then it becomes 'locked'.

I've seen this with my own eyes, I have tried multiple times to flash the latest ECU firmware using the CLIP and both online download and Renault's CDs and I always get a stupid 'ECU has already been flashed' message.

My ECU was flashed almost 4 years ago, and I still have the hesitation when cold problem... I really would like to know if the latest firmware solves this.

What is mind-boggling is that some cars (most of them) exhibit this and others don't, even cars built within the same month... :S

[megane10]

Hi, today I was driving for around an hour, I then went to the petrol station turned the car off and once I started the car again and left the engine management light and the service light came on permanently, however the car was running fine when driving it home. (The car has recently been serviced around 500 miles ago.) I do know that my back breaks and front shock passenger side need replacing could this contribute to the warning lights coming on????

[dougieCC]

Could be cam shaft sensor? search on it, a few topics.

Alan

[markren2004]

yes most likely candidate is the cam sensor. see common issues sticky viewtopic.php?f=2&t=8855

if your in AA / RAC they will read the codes from the computer for you to confirm.

[Wazza4]

I have just purchased a 2nd hand 1.6 16v ( about 2 months ago ) and I have had this problem since purchase, the car has been in the garage 5 times in the past 7 weeks and they still cant find the issue.
I have managed to get my hands on some of the Renault technical notes and have found out that new dephaser pullys that are sent out as spare parts are not locked, there is an inner hub on the dephaser pully that needs to be turned until it is locked in place before the part is fitted to the new engine, what they found is that most of these were not locked when they came from Renault Spares and this causes the timing to be affected and the car will lose power and hesitate especially when the unit was cold, once the engine had warmed up this issue would dissapear..... this is exactly the fault that we are all having

Now I have gone through more of these Actis Solution updates (Renaults technical support database) and have found that the following needs to be tested for the above fault K4M 760 - 782 Engine models:

1: Check if injection software is older than A7.73 if it is then update with V31 or newer ( They use Technical Note 3585A for doing this update )
2: Test the camshaft dephaser solenoid valve - Replace if need be
3: Test camshaft dephaser pulley - Replace if need be ( This needs to locked before it is fitted )

The above is from the 4432A technical report for instability and engine hesitation

What it seems is that they are not locking these in place before fitting... hence some dephaser changes are fixing the problem others are not.

Mine was replaced 2 weeks ago and it did not fix the problem so i am sending the car back tomorrow to be checked out again, will ask for a full report on what has been done and will be telling them about locking the dephaser pulley and also about technical note 4432A and to try that.

I know that the dephaser pully, tensioners, timing belt and 2 sensors (dont know which ones but will check) have been changed so far.

I have a full 2 year extended warranty when I got the car so if it takes Renault 2 years and thousands of pound of there own money to find out what the issue is then they will have to do it... rest assured I will find a resolution for this problem....

Will be in touch shortly

Fingers crossed

[MONDO9]

Where do you get these technical notes? is anyone saving them to this forum somewhere...would be usefull!!!

[snowy]

clean the throttle body...worked for me

[MONDO9]

clean the throttle body...worked for me

Ive cleaned my throttle body that many times its almost got a mirror finish!!!! Still didnt solve the problem!

Also, surely if you are unlucky to have an unlocked dephaser fitted, the car would be pish all the time not just at cold start. A car heating up does not adjust something that is mechanically set wrong!