Renault megane scenic 1.4 16v misfire


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By billlincs - January, 2006
hi all

i have a megane scenic 1.4 16valve in, sorry i don't have the engine code at the minute. problem is a misfire throughout the rev range. i thought it would be a coil gone, as with the engine running,(badly) if you unplug coils on number 1 and 4 plugs, the engine dies, but unplug no. 2 or 3 and it makes almost no difference. swapped coils( 1-2&3-4) and fitted new plugs, still the same. compression fine on all cylinders. anyone had the same? no codes, except coil circuit, caused by me disconnecting them!

do the injectors cause any problems on these.

please help,

bill

By ovy1255 - January, 2006
wen u say injectors is it multi point or 4 seperate
By ovy1255 - January, 2006
are 2-3 plugs firering [feeds to coil 2-3]
By billlincs - January, 2006
thanks ovy,

didn't get chance to check feeds, thought it was bound to be the coils, as we've had loads of those go. is there a seperate signal for cyls 1&4 and cyls 2&3?

bill

By Speedy - January, 2006
Had this a while back with a 1.6 megane ..................

Turned out to be a faulty coil Wink

By manicmotors - January, 2006
bill

what year is it?

martin

By billlincs - January, 2006
Sorry martin, it's a 2001

bill

By Dave Hill - January, 2006
These modern coils are weired when they fail

I have noticed on Focus's mainly that when the coil packs fail on a cylinder, when you pull the offending cylinder HT lead off, that they actually run better, as opposed to not making any difference. Whats that all about?

DH

By DaveH - January, 2006
Pull off each injector plug in turn to indentify which cylinder then replace that coil pack !!!!

DaveH

By ovy1255 - January, 2006
i wud check if 2-3 plugs are wet

check all for spark

double check compresion [h/gasket between cylinders]

feeds to coils

but like u i have changed loads of these and always in 2s

By billlincs - January, 2006
thanks daves,

i swapped the 2 firing outer coils, with the inner two, and it made no difference, so i'll check feeds and injectors tomorrow.

first job is the old austin 6 though... 1 carb, 1 coil, suck squeeze bang blow! wish i were born around 1930!

bill

By manicmotors - January, 2006
bill

i have a feeling there is a problem with earths on these i will check in the morning at work

martin

By DaveH - January, 2006
Bill,

I did all that and it was still one coil....Smile

See if you can get hold of a test one and swap them one at a time !

DaveH

By K And R - January, 2006
Bill.

Do as Dave says pull the injector plug as this gives a better clue than the pulling the plug to coil. One other thing if it one coil  has gone fit all four as they are getting updated all the time, and if one has gone the others won,t be far behind.

Kevin.

By Mike H - January, 2006
The coils on renault are wired in pairs, if I'n not mistaken 1&4 and 2&3 in series, thats why its easier to pull of the injector plugs to identify which cylinder is misfiring.

As for cahnging all 4 coils, check the make. If its Sagem change all 4....
Denso and JCAE are much better quality.Cool
By gary - January, 2006
COILS ARE WIRED IN PAIRS ON RENAULTS SO KNOCK OFF INJECTORS INSTEAD. HAVE CHANGED ALOT COILS ON THESE ENGINES
By billlincs - February, 2006
Hello again,
Very sorry but i thought i'd already posted on curing this one, i changed the coils on cyls 2&3 and everything was fine.....
Until yesterday when it came back with exactly the same problem! Pulling leads from coils 2&3 makes it run better! pulling coil 1 or 4 stalls it, and pulling injectors 2 or 3 makes no difference.
it's been only three weeks and around 1500 miles since i "fixed" it, so what could be causing it to fail so soon? I spoke to renault and they have no problem replacing the two coils under warranty, but will the next two fail so quickly too?
i fitted new NGKSad plugs at the same time as the coils, could this be a problem?
Compresion test ok, sagem coils, from Renault,( where do you get the others?? Denso etc?)
Any help much appreciated.
Bill
By Dave Hill - February, 2006
Bill

Just a thought I know unlikely, but it should be ruled out. I have had problems with inlet fanymould gaskets giving me the run-around on these engines. Also head gasket failure in between cylinders two & three??? They can give unexpected compression test results.

Cheers!

 

By K And R - February, 2006
Bill.

Dave could be right,BigGrin it will be a firstBigGrinBigGrinBigGrinBigGrin. sorry dave, please don,t send Paula to kick meBigGrinBigGrin. but there should be numbers on the coils to know if they are the latest. If your dealer won,t confirm yours are the latest please PM me the numbers and i will check them or just post them and i suspect some-one will beat me to itBigGrinBigGrinBigGrin.

KEV.

By billlincs - February, 2006
Thnks dave, but why should fitting new coils cure it for a few weeks if it's an air leak or head gasket prob?
Kev... i'll post and pm the numbers tomorrow when i get to work
thanks
bill
By Dave Hill - February, 2006
Bill

I agree totally mate, but surely you have been in the game long enough to know that sometimes there seems to be little logic involved in these types of faults.

I posted a while back about a Scenic 1.6, 8 valve that we did a head gasket replacement for a local Vauxhall dealer. We had a good few hours afterwards chasing a misfire that was there one minute & wasn't the next. That turned out to be the inlet manifold gasket. I was amazed how random it was.

I am still learning (The hard way sometimes) to check the things that you would normally rule out before moving onto more costly areas.

Cheers!

 

By billlincs - February, 2006
I think you've jinxed me Dave.
Changed all coils and plugs (again)., still the same Sad.
Checked all round for air leaks, compression tested and... Cylinder 3 down about 25%,( cyl 2 ok!), although it was ok when the car came in the first time! maybe it already had a slight leak and the plugs/coils change made it unnoticeable?
I'll whip the top off after lunch and will let you know what i find.
Bill
By maxmell - February, 2006
Bill

Dont want to muddy the already murky waters but we had a clio

in with the same engine last week,similiar fault turned out to be 2

injectors.

By DaveH - February, 2006
BigGrinWinkBigGrinWinkBigGrinWinkBigGrinWinkBigGrinWinkBigGrin   Don't ask !!

DaveH

By billlincs - February, 2006
how did you trace it to the injectors neil?
i think i'm gonna change jobs.....
all getting tooo heavy
thinkin of becoming a binman!
bill
By maxmell - February, 2006
Bill

Last resort!was an intermittant slight miss usualley under load tried coils etc,luckily i was able swap the injectors and rail from another car.

Although they were working i think they were slightly blocked.

Binman sounds good pay/pension/working hours/stress etc etcBigGrin

(forgot customers and finish at dinnertime)

By Dave Hill - February, 2006
Neil

You forgot to mention that they only work one day a week.    w00tw00t

Cheers!