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Possible causes of missfire - checked all sorts



williams-ant

ClioSport Club Member
172 cup.

Was running fine and after being sat on the drive for about 3 to 4 weeks it developed a missfire.

It had new OEM leads and new ngk laser plat plugs.

Eml flashing and then solid, stinks a bit.


I pulled 2 of the injectors and found them to be a bit dodgy so replaced them

Obd brings up P030 random cylinder missfire, but it’s the gearbox end pot that’s causing issues.

Tried swapping an old plug on that cylinder, no change.

Tried a mates coil pack, no change.

Put my old leads back on, seemed to sort it and then it’s back again.

Just wondered if there could be a dodgy connection somewhere and where that might be?

Or a faulty sensor, fault on a harness plug, ecu connector etc

Any ideas?
 

william84

ClioSport Club Member
  182 clio
Make sure he leads are fully connected was a pain to get mines to click on plugs.
Mirroring injector likely. Was OE injectors you replaced with?
 
Mirroring injector? They were supposed to be Genuine ones but I’m
Not convinced
Hi
sounds like you are having the same problem as me on my 182 - Loads of comments saying change the injectors, which does seem to work in many cases ... but not for me .... 4 new injectors, 4 new HT leads, new coil and still the OBD reports missfire on cylinder 1 ... which is the gearbox end ...... If you get any tips on other sensors etc. to check then I'll be really interested .... good luck with it
 

williams-ant

ClioSport Club Member
Bloody pain in the arse these clios! Keep
Me posted!

I wondered if it might be an ecu connection issue or something
 

Brigsy

ClioSport Club Member
  Kangoo 172cup
Have you tried another injector in the cylinder thats misfiring? Noid light to check the wiring? Are the new spark plugs same as oem as i read other brands can cause issues. Every time ive had a misfire its been injector or ign related.
 

williams-ant

ClioSport Club Member
Yes I swapped the injector plug over to see if that did anything, proved the harness was playing the injector. Then swapped injector over and was the same.

Plugs are ngk OEM spec, platinum oft or whatever it is, but correct spec anyways.
 

william84

ClioSport Club Member
  182 clio
Yeah. Try swapping them round.
Make sure none of your Ht leads are trapped by plenum also
 

william84

ClioSport Club Member
  182 clio
Hi
sounds like you are having the same problem as me on my 182 - Loads of comments saying change the injectors, which does seem to work in many cases ... but not for me .... 4 new injectors, 4 new HT leads, new coil and still the OBD reports missfire on cylinder 1 ... which is the gearbox end ...... If you get any tips on other sensors etc. to check then I'll be really interested .... good luck with it
have you tried o2 sensors?
or even the knock sensor it's self
 

william84

ClioSport Club Member
  182 clio
o2 sensor most likely if you've checked changed all above in you post.
I've never had the experience of one being at fault but have heard of that causing a misfire issue.
most misfire issues are down to injectors or spark delivery.
Which simple resistance checks would diagnose.
if all is fine with those checks o2 sensors would be next.
clip would give more accurate diagnostic and where to start.
 

william84

ClioSport Club Member
  182 clio
o2 sensor most likely if you've checked changed all above in you post.
I've never had the experience of one being at fault but have heard of that causing a misfire issue.
most misfire issues are down to injectors or spark delivery.
Which simple resistance checks would diagnose.
if all is fine with those checks o2 sensors would be next.
clip would give more accurate diagnostic and where to start.
knock sensor should be above oil filter I'm sure there is a thread somewhere on here showing all the sensors
 
Back on it again this weekend ...... so ...
1. Disconnected two sensors on the front of the engine see photo ..... I assume the one top right (red/white leads) is the knock sensor with very awkward cable connector and the other left of oil filter with only one lead is ???? and I did not touch the one below the oil filter that I assume is an oil level sensor
results in no change to EML warning (misfire on cylinder 1) and engine always running well
2. O2 sensors - I tried to remove them to do a swap test but it seems to be impossible using an adjustable spanner with extension bar ~50cm .... pleased nothing broke ..... but nothing came undone either ... any tips will be very welcome
3. so tried just leaving the O2 sensors disconnected .... resulting in
post cat sensor = off => misfire on cylinder 1
pre cat sensor = off => O2 bank 1 error
both off => O2 bank 1 error
HELP!!!!
 

Attachments

william84

ClioSport Club Member
  182 clio
Back on it again this weekend ...... so ...
1. Disconnected two sensors on the front of the engine see photo ..... I assume the one top right (red/white leads) is the knock sensor with very awkward cable connector and the other left of oil filter with only one lead is ???? and I did not touch the one below the oil filter that I assume is an oil level sensor
results in no change to EML warning (misfire on cylinder 1) and engine always running well
2. O2 sensors - I tried to remove them to do a swap test but it seems to be impossible using an adjustable spanner with extension bar ~50cm .... pleased nothing broke ..... but nothing came undone either ... any tips will be very welcome
3. so tried just leaving the O2 sensors disconnected .... resulting in
post cat sensor = off => misfire on cylinder 1
pre cat sensor = off => O2 bank 1 error
both off => O2 bank 1 error
HELP!!!!
Pre soak o2 sensors with wd or likes of.
give round it a good wire brush and soak again.
try a pipe wrench on them that way should grip without slipping
 
Thanks for the tips ..... but my 22mm spanner is not slipping off ..... it's just not budging anything either .... being limited to garage floor with axle stands means is't impossible to get anything longer than 50cm on them ...... I'll try the wire brush and leaving the wd40 to soak overnight ..... if at first you don't blah blah....
 

Daz...

ClioSport Club Member
  Clio 182 Cup
If it still doesn’t move try shocking it by hitting the spanner with a hammer.
 

bashracing

ClioSport Club Member
  1993 micra
Do a compression test, if that that doesn't show anything take it to a garage that knows how to use a lab scope it'll be cheaper than the old parts cannon
 
@ Bashracing .......
I have checked the compression it's 180/195/180/180 for 1,2,3,4 ..... tested with all plugs out running engine on starter motor until the gauge maxes out
I have checked and swapped around the plugs (fairly new)
I have changed the coil for new
I have changed the HT leads for new
I have changed all four injectors for new
I have swapped the O2 sensors around
nothing seems to fix it .......
=> flashing engine warning light ..... only at low speed/stop/start .... goes off during any continuous use after a few minutes .... no power loss at any point
error message is alway 'misfire cylinder 1'
 

Daz...

ClioSport Club Member
  Clio 182 Cup
You’ve listed lots of changed parts, but did you check the plugs?

Edit- ignore that, you’ve mentioned them above 🤦🏻‍♂️
 

william84

ClioSport Club Member
  182 clio
@ Bashracing .......
I have checked the compression it's 180/195/180/180 for 1,2,3,4 ..... tested with all plugs out running engine on starter motor until the gauge maxes out
I have checked and swapped around the plugs (fairly new)
I have changed the coil for new
I have changed the HT leads for new
I have changed all four injectors for new
I have swapped the O2 sensors around
nothing seems to fix it .......
=> flashing engine warning light ..... only at low speed/stop/start .... goes off during any continuous use after a few minutes .... no power loss at any point
error message is alway 'misfire cylinder 1'
hmm 🤔
I'm not sure if crankshaft sensor can cause misfire codes I know it can cause the engine to cut out. Have you checked all the wiring for injectors? Also check crankshaft sensor plug wiring.
 

williams-ant

ClioSport Club Member
So mines still the same, it’s had new injectors, new plugs, new leads, new coil and just swapped around the two lambdas. Still the same, it’s pot 3 that’s giving me greif not pot 4
 
@ William84
OK something new to look at :)
wiring is mostly heavily protected under plastic conduit ..... nothing obvious but I will look again more closely
crankshaft sensor... hmmm well it starts first time every time and runs very well ...... so seems a very very long shot to me ... but again ... I'll take a look at it ...
 

bashracing

ClioSport Club Member
  1993 micra
@ Bashracing .......
"old parts cannon" = ???
It's a mechanics saying when someone has put lots of new parts on something to fix it rather than diagnosing which has actually failed.

A decent diagnostic tech with a lab scope will tell you what the issue is, ( it's not always a component failure sometimes it's a bad connection or damaged wire which no end of new parts will fix)
 

williams-ant

ClioSport Club Member
Is there anywhere around warrington area I could take this to get sorted? It’s doing my nut now and absorbing too much of my time!
 

william84

ClioSport Club Member
  182 clio
I'm thinking the same ..... Is a Renault agent the best place (Renault tools) or a specialist tuning garage ??
put a post asking for advice on garage near you with renault sport knowledge.
Is there anywhere around warrington area I could take this to get sorted? It’s doing my nut now and absorbing too much of my time!
put a post asking for advice on garage near you with renault sport knowledge.
 


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