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Spark plug change now engine misfire

AnalStick

By AnalStick,
in General Maintenance

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AnalStick Enthusiast

AnalStick

Posted
Posted

So i just changed my sparkplugs on my r34 everything was fine I drove it for like 10 minutes and then the engine light came on and then it started misfiring really bad, now on idle, it sounds like its running on fewer cylinders. I got engine fault code 21

Duncan Grand Master

Duncan

Posted
Posted

moved to general maintenance.

and.....have you checked everything since the drive? all plugs tight, all coil packs securely bolted down, all coil pack loom plugged in OK? And the coil pack earth if you undid it?

Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

Or the plugs in there before were gapped very small, and now new plugs have a larger gap.

Or old plugs were gapped stupid small on purpose to mask any coil pack issues. If the coil pack's colour is on the left hand side of the colour spectrum then there's part of your problem.

Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

You'll find coil packs in the following colours, ie the left hand side of the colour spectrum are 9/10 the root of your problem(s) with a car that is running more than stock boost.

Red Orange Yellow Green? (Eventually) lol.

Anyone remember ROYGBIV? 

AnalStick Enthusiast

AnalStick

Posted
  • Author
Posted
3 hours ago, Dose Pipe Sutututu said:

You'll find coil packs in the following colours, ie the left hand side of the colour spectrum are 9/10 the root of your problem(s) with a car that is running more than stock boost.

Red Orange Yellow Green? (Eventually) lol.

Anyone remember ROYGBIV? 

I forgot to mention my car is non turbo 

Dylannn Contributor

Dylannn

Posted
Posted (edited)

what coilpacks you running Anal? I've got some OEM ones if you need, $20ea.

I'd do the following diagnosis

Remove 1 coilpack and start the car and see if the miss gets worse, if the miss gets worse then you know that coilpack / plug is working as it should be for that cylinder, repeat this for all cylinders and you should find out which cylinder is not firing. Once this happens swap a known good coilpack onto this to determine if its the coilpack at fault or something else..

 

Report back findings!

Edited by Dylannn
AnalStick Enthusiast

AnalStick

Posted
  • Author
Posted
5 hours ago, Dylannn said:

what coilpacks you running Anal? I've got some OEM ones if you need, $20ea.

I'd do the following diagnosis

Remove 1 coilpack and start the car and see if the miss gets worse, if the miss gets worse then you know that coilpack / plug is working as it should be for that cylinder, repeat this for all cylinders and you should find out which cylinder is not firing. Once this happens swap a known good coilpack onto this to determine if its the coilpack at fault or something else..

 

Report back findings!

Thank you I'll do the testing as soon as I can 

AnalStick Enthusiast

AnalStick

Posted
  • Author
Posted
5 hours ago, Dylannn said:

what coilpacks you running Anal? I've got some OEM ones if you need, $20ea.

I'd do the following diagnosis

Remove 1 coilpack and start the car and see if the miss gets worse, if the miss gets worse then you know that coilpack / plug is working as it should be for that cylinder, repeat this for all cylinders and you should find out which cylinder is not firing. Once this happens swap a known good coilpack onto this to determine if its the coilpack at fault or something else..

 

Report back findings!

so i started my car and it ran fine and again after driving and warming up the engine the engine light came on after about 10 mins. then it slowly started getting misfires as i kept driving the car. could i have put a vacuum hose in the wrong place

Dylannn Contributor

Dylannn

Posted
Posted

 

32 minutes ago, AnalStick said:

so i started my car and it ran fine and again after driving and warming up the engine the engine light came on after about 10 mins. then it slowly started getting misfires as i kept driving the car. could i have put a vacuum hose in the wrong place

Check codes on ECU, that will point you in the right direction from here

Dylannn Contributor

Dylannn

Posted
Posted
12 minutes ago, AnalStick said:

i did a code check and i got code 21 which means ignition signal, its very vague 

I’d try diagnosis outlined above and see if that helps finding what’s causing the issue

Jjtxaz24 Collaborator

Jjtxaz24

Posted
Posted

Check and make sure your pigtails on your injectors are good. Just push em in, unplug em, clean em and add some dialectic grease. 

I had a misfire and after changing coils, plug, harness and ignitor box i ended up jiggling the injector plug on the cylinder that was misfiring and issue was resolved.  

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