Cause of Misfire?

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grandadbobby
Advanced Driver
Posts: 499
Joined: Thu Feb 16, 2017 9:05 pm
Currently Drives:: megan dynamique estate 1.9dci

Re: Cause of Misfire?

Postby grandadbobby » Tue Apr 11, 2017 9:58 pm

Hi,
sorry you're back on this, makes you wonder if you're dealing with a faulty batch of coils.
Try one of your old original ones if you've still got them.
Good luck, keep us informed
Bob.

57jam89
Posts: 18
Joined: Sat Jan 16, 2016 4:25 pm

Re: Cause of Misfire?

Postby 57jam89 » Wed Apr 12, 2017 11:29 am

Update- my new misfire is again on/off, I can drive for 10 minutes (hot or cold engine) and it's running fine and just like you throw a switch the misfire starts.

Just checked codes and now have 'misfire cylinder 2' and also 'misfire due to low fuel level' but fuel tank is about half full!

Also I had to stamp on the brakes today and the misfire stopped and was fine for next 20 mins!

quaker@eircom.net
Learner Driver
Posts: 55
Joined: Sat Nov 29, 2008 4:22 pm
Currently Drives:: renault megane 2005 1.5dci automatic

Re: Cause of Misfire?

Postby quaker@eircom.net » Wed Apr 12, 2017 10:26 pm

If you could get a small cannister of propane fitted with a long pipe nozzle with an on/off valve...then when the engine is misfiring try to inject a small quantity of the propane into to the inlet air stream ( by teeing into the vacuum pipe )..then if the misfiring stops then that tells you its a fuel issue rather than a spark issue. Could a faulty brake pedal switch cause your symptoms? Jamming on the brakes caused the engine to run okay for 20 mins?.
rgds Maurice

grandadbobby
Advanced Driver
Posts: 499
Joined: Thu Feb 16, 2017 9:05 pm
Currently Drives:: megan dynamique estate 1.9dci

Re: Cause of Misfire?

Postby grandadbobby » Thu Apr 13, 2017 12:01 am

The fault code for 3 was right last time, l suspect it's right this time.
ln the past l have known new plugs to go faulty, never mind these new fangled coils. l suspect they are from China like everything else.
You'll fix it, you did before, you're just having bad luck at the moment.
l would have thought that any code for fuel might be a suspect injector, just a thought. lntermittent faults are always the worse.
Bob.

57jam89
Posts: 18
Joined: Sat Jan 16, 2016 4:25 pm

Re: Cause of Misfire?

Postby 57jam89 » Thu Apr 13, 2017 5:08 pm

Hi,
What I can't work out is the ECU coming up with 'misfire due to low fuel level' the only way it can see the fuel level is by the fuel tank level sensor which is showing half full on dash.

And I know there is no fuel pressure sensor on the fuel rail so does the ECU maybe mean misfire due to low fuel pressure????
Also how does the ECU work out whats causing a misfire?

Thanks.

quaker@eircom.net
Learner Driver
Posts: 55
Joined: Sat Nov 29, 2008 4:22 pm
Currently Drives:: renault megane 2005 1.5dci automatic

Re: Cause of Misfire?

Postby quaker@eircom.net » Thu Apr 13, 2017 7:22 pm

hello there.....re fuel and fuel pressure...the fuel pressure should be around 43-48 psi at the fuel pressure monitoring nozzle on the fuel distribution unit ( normally its a fuel rail with the injectors connected to it)...this can be measured with a bit of clear piping and a suitable pressure gauge. The pressure could be low due to a dirty fuel filter ( if one exists) or a suspect fuel pump. If you have low fuel pressure then the amount injected by the injector is going to be reduced and this could lead to a lean mixture and possibly a misfire. Worth checking.
Maurice

57jam89
Posts: 18
Joined: Sat Jan 16, 2016 4:25 pm

Re: Cause of Misfire?

Postby 57jam89 » Fri Apr 14, 2017 2:50 pm

quaker@eircom.net wrote:hello there.....re fuel and fuel pressure...the fuel pressure should be around 43-48 psi at the fuel pressure monitoring nozzle on the fuel distribution unit ( normally its a fuel rail with the injectors connected to it)...this can be measured with a bit of clear piping and a suitable pressure gauge. The pressure could be low due to a dirty fuel filter ( if one exists) or a suspect fuel pump. If you have low fuel pressure then the amount injected by the injector is going to be reduced and this could lead to a lean mixture and possibly a misfire. Worth checking.
Maurice


Hi, just had a good look and there's no nozzle on this engine any where so checking fuel pressure is not going to be easy.
I have disconnected the wires from fuel pump with it running /misfiring and it run on for about a 1 min so I'm thinking if the misfire is because of lack of fuel pressure surly it would die straight away.

So I'm back to thinking maybe a wiring fault so anyone know where I can find a wiring diagram of engine management?

Thanks.

57jam89
Posts: 18
Joined: Sat Jan 16, 2016 4:25 pm

Re: Cause of Misfire?

Postby 57jam89 » Fri Apr 14, 2017 6:05 pm

Update - now have codes
P0300 - ramdom/multiple cylinder misfire
P0638 - throttle actuator control range performance
P0353 - ignition coil c primary /secondary circuit
P0352 - " " b " "
P0323 - misfire due to low fuel level.

Where do the hell do I start!

Anyone know where I can get a wiring diagram?

grandadbobby
Advanced Driver
Posts: 499
Joined: Thu Feb 16, 2017 9:05 pm
Currently Drives:: megan dynamique estate 1.9dci

Re: Cause of Misfire?

Postby grandadbobby » Fri Apr 14, 2017 10:00 pm

Hi again, this is what l have found
P0323 crankshaft position sensor circuit intermittent this had you fooled
P0352 ignition coil cylinder 2
P0353 '' '' '' 3

l reckon the other two codes are caused by the misfire. l also think the coils could be missing because of the crank sensor, but you should be able to swop them with 1 and 4 and see if codes change.
l can't remember if you changed the crank sensor, but even if it's new, the connections to it and the wires need checking as it's intermittent, there could be a break. You even have to check continuity where the wire connects to the connector at it's end, l've had that on a Clio and it happens.
Good luck
Bob.

57jam89
Posts: 18
Joined: Sat Jan 16, 2016 4:25 pm

Re: Cause of Misfire?

Postby 57jam89 » Sat Apr 15, 2017 6:56 am

grandadbobby wrote:Hi again, this is what l have found
P0323 crankshaft position sensor circuit intermittent this had you fooled
P0352 ignition coil cylinder 2
P0353 '' '' '' 3

l reckon the other two codes are caused by the misfire. l also think the coils could be missing because of the crank sensor, but you should be able to swop them with 1 and 4 and see if codes change.
l can't remember if you changed the crank sensor, but even if it's new, the connections to it and the wires need checking as it's intermittent, there could be a break. You even have to check continuity where the wire connects to the connector at it's end, l've had that on a Clio and it happens.
Good luck
Bob.


Hi, you say P0323 crankshaft position sensor circuit intermittent but it reads P0323 - misfire due to low fuel level reads on my obd reader.

The crank senser was replaced about a year ago.

Thanks.

quaker@eircom.net
Learner Driver
Posts: 55
Joined: Sat Nov 29, 2008 4:22 pm
Currently Drives:: renault megane 2005 1.5dci automatic

Re: Cause of Misfire?

Postby quaker@eircom.net » Sat Apr 15, 2017 11:43 am

Hello there......Normally ignition coils are ground( earth) switched by the ecu....the ecu provides an earth pulse to trigger the ignition coil. If the coil has two wires feeding to it then you need to identify which one gets the earth pulse from the ecu.Turn on the ignition....disconnect both wires from the coil of cyl 3 ( possibly its a plug)...check which one of the wires has battery + on it...then the other wire should be the one getting the earth pulse from the ecu ( this earth wire may have a biasing voltage it but it should be less than the battery+). Restore everything. Now if at all possible obtain a LED type bulb and connect one end to the +ve battery terminal and the other end to the earth pulse wire of the ignition coil. During cranking of the engine you should see this bulb flashing. If not sure do it to the other three coils to see what a good one pulses like. If the misfire is occuring, you should see an absense of light flashes when connected to the wire of cyl no 3. Ideally an oscilloscope would show more detail. Or an voltmeter set on the dc volts scale might do but the LED bulb is better.Maurice.

grandadbobby
Advanced Driver
Posts: 499
Joined: Thu Feb 16, 2017 9:05 pm
Currently Drives:: megan dynamique estate 1.9dci

Re: Cause of Misfire?

Postby grandadbobby » Sat Apr 15, 2017 1:15 pm

Hi,
l googled 'renault fault codes', just to check, there's a couple of good sites give codes and what they mean.
They both said the same.
Bob.

57jam89
Posts: 18
Joined: Sat Jan 16, 2016 4:25 pm

Re: Cause of Misfire?

Postby 57jam89 » Fri Apr 21, 2017 5:45 pm

Update - After carefully checking every wire from ecu to engine and fusebox and finding all ok. I decided to go to the breakers and got some coils.

And the cause of my problems is 2 more coils are faulty!

So 4 out of 4 coils turned faulty! EBay seller is refusing to refund me!

grandadbobby
Advanced Driver
Posts: 499
Joined: Thu Feb 16, 2017 9:05 pm
Currently Drives:: megan dynamique estate 1.9dci

Re: Cause of Misfire?

Postby grandadbobby » Fri Apr 21, 2017 8:40 pm

Hi again,
let's hope that's the end of it.
Phone ebay customer service, l'm sure they will sort it.
New stuff has to have some sort of guarantee.
Good luck
Bob.

dijef
Posts: 2
Joined: Sun Jul 08, 2012 1:45 pm
Currently Drives:: Renault Megane II 2003 1.6

Re: Cause of Misfire?

Postby dijef » Tue Jun 13, 2017 8:30 pm

hi. I have the same problem with my Megane II 1.6 from time to time. I googled it before and found issue with Megane I where guy said it was fixed by electrician. It was because of earth to the engine not being correct as collegue above mentioned. I gave it cleaning and issue gone away for two months but it comes back from time to time. It only happens at engine temperatue and goes away if misfiring and I drive so it gets cooled by air.


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