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Discussion Starter · #1 ·
2006 wrx misfires at idle only. The car is fine until it warms up and then it starts misfiring like crazy and the cylinder roughness goes up to like 75 sometimes and sometimes I’m at a light and it doesn’t misfire whatsoever but sometimes it idles so it’s super random. The car runs amazing under load so I don’t know what it is. I’ve done all the basic things like coil packs, moved around the injectors, cleaned the maf, moved the sparks plugs around, unplugged the front 02 sensor, cleaned the cam sensor and nothing changes. I’ve yet to changed out the plugs Bc I just bought the car and the previous owner said he had just changed them. Any other things I’m missing? I’ve seen other forums where it says it could be a bad valve or it would need valve readjustment Bc it only does it as idle when it warms but when it’s cold it idles just fine.
 

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Clean the throttle body first and then comp test it if still a problem. It won't go pop in a cylinder if there's no compression.
 

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Check spark plug gap, I dont trust anyone to do something right. Auto part stores will tell people that the plugs are pre gapped... they may be good enough gapped for a Ford Ranger but for a turbo charged engine get those gaps set right. Other issues might be old/bad gas or voltage issues but I doubt the latter. Im guessing gap is to big on a cylinder and at low compression its having problems firing.
 

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Discussion Starter · #4 ·
Check spark plug gap, I dont trust anyone to do something right. Auto part stores will tell people that the plugs are pre gapped... they may be good enough gapped for a Ford Ranger but for a turbo charged engine get those gaps set right. Other issues might be old/bad gas or voltage issues but I doubt the latter. Im guessing gap is to big on a cylinder and at low compression its having problems firing.
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Check spark plug gap, I dont trust anyone to do something right. Auto part stores will tell people that the plugs are pre gapped... they may be good enough gapped for a Ford Ranger but for a turbo charged engine get those gaps set right. Other issues might be old/bad gas or voltage issues but I doubt the latter. Im guessing gap is to big on a cylinder and at low compression its having problems firing.
what should they be gapped at?
 

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Could be one of a few things.

I'd start simpler than assuming valve. Try to look for vacuum leaks. Absolutely check plugs, although if they are platinum or iridium you can't check them with a traditional gap tool and need shims. It's very very critical you are gentle with the plugs as they are fragile.

To be honest I've never picked up an iridium or platinum plug that wasn't gapped at 030. The gap range for the EJ if I recall was like 029 to 032 or some such in that range.
 

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what should they be gapped at?
0.028-0.031. I did have a friend that replaced her sparkplugs one time and slightly broke the connector inside the spark plug wire too. You could run a resistance meter between the wire and end of plug. Would give an indication of the condition of the two.
 

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Discussion Starter · #7 ·
0.028-0.031. I did have a friend that replaced her sparkplugs one time and slightly broke the connector inside the spark plug wire too. You could run a resistance meter between the wire and end of plug. Would give an indication of the condition of the two.
Update: cylinder 2 compression is 32 lmao
 

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I'd recheck compression. I was checking it on a motor not long ago and had a low reading that turned out to be user error with the compression tool.

Edit: also make sure the motor is cold cold. If its even slightly warm you can get false readings. Correct me if I'm wrong but I think that's right.
 
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