Looking for misfire diagnosis guide

[glittlewood98]

Hi everyone, sorry for yet another misfire thread.
I'm looking for a guide on diagnosing the misfire, someone wrote a really thorough one years back and I've spent hours trying to find it again with no luck.
Anyone able to help me out?
Thanks

 

[JamesBryan]

Need a bit more information.

When is it doing it, on idle or under load?

Any warning lights/EML?

Have you scanned for codes?

 

[Clio.lee]

It’s going to be one of the following

Coilpack
Spark plugs
Fuel pump
Compression

 

[glittlewood98]

Need a bit more information.

When is it doing it, on idle or under load?

Any warning lights/EML?

Have you scanned for codes?

More info,
Cylinder 1 is down, sometimes intermittent sometimes permanent, immediately thought it was an injector so replaced that, very slight improvement.
Next thought was the ebay map sensor as it went to 3cyl under harder throttle load so replaced for an oem map sensor - no change
Replaced the HT leads - no change
Strong spark from coil, I havent had the plugs out yet as I can't find my socket
I'm thinking it might be throttle pedal or throttle body at this point, need to check the plugs first though

 

[dave120]

Checked injectors?

 

[JamesBryan]

More info,
Cylinder 1 is down, sometimes intermittent sometimes permanent, immediately thought it was an injector so replaced that, very slight improvement.
Next thought was the ebay map sensor as it went to 3cyl under harder throttle load so replaced for an oem map sensor - no change
Replaced the HT leads - no change
Strong spark from coil, I havent had the plugs out yet as I can't find my socket
I'm thinking it might be throttle pedal or throttle body at this point, need to check the plugs first though

There should be an error code for most of those situations.

 

[glittlewood98]

Checked injectors?

Yeah, it wasn't the issue

 

[glittlewood98]

There should be an error code for most of those situations.

Need to get it on a code reader ASAP I reckon yeah

 

[Sidnancy]

SO, I had this problem with my clio a few years back. Im going off memory so bare with me here:

As said above, its going to be one of the following: Compression, Spark Plugs, Coil Pack, HT Leads or Injectors.

Injectors - You need to test the resistance across them. Multimeter time! Youtube is good for tutorials on these and a wuick search on here will show you what they should read.
HT Leads - Whip them off and check with a multimeter for continuity. Good guides for this on youtube.
Coil Pack - Not a scooby how to test these. Theyre cheap to replace if you get that far.
Spark Plugs - Again, quite cheap and might aswell replace them, never going to hurt.
Compression - Arguably the hardest to determine as most people dont have a compression tester laying about. I would personally attack this one last as its also going to be the most costly to repair if it is compression.

9 times out of ten (from what I can gather on this forum and it was true in my case) its going to be injectors. I tested the resistance across mine and they were fine. Well, they werent as a replacement set sorted it. IRRC theyre about £120 for a set. DO NOT buy anything other an OEM renault ones as the cheap chinese copies are usually junk - trust me on this.

Code reading is a definite help. It will tell you what the code is and which cylinder it is too. A quick help is to switch injectors around to see if the misfire moves. Same goes with HT leads but make sure they correspond to the correct hole in the coil pack or else the car will be firing in a very weird order. Sounds very bad, trust me.

Good luck

 

[Martin_172]

Any time I come across one on a Clio its an injector, coil pack or lead (sometimes people trap them under the inlet when refitting).

First for me is always a code read, see what the car is saying and check the live data to make sure everything's as it should

Then I always check the resistance on the injectors, a member from here posted a guide on YouTube that's handy: Five Ways to Diagnose Injector Misfires - YouTube

if the car hasn't had plugs in the last 3 years, may as well change them as its maintenance anyway, Always check the gap as I fitted 4 or 5 sets last week and a good few of them were out of spec out the box!

If you have confirmed its cylinder 1 then swap the injectors, plug (if you didn't change them) and leads around and see if you can rule them out by making the miss fire move.

From there id usually stick a coil pack on it as its most likely the culprit if the above has all been ruled out, and if not, move to a compression test

 

[jameswrx]

Did you also use an OE injector?