Intermittent cylinder 4 missfire and breakup at peak boost

[Corey Wilson]

Hey guys, so I've been having some issues with my speed 3 lately and I'm struggling with figuring out what it is. So the car runs smooth at idle and during regular driving but as soon as I hit peak boost it breaks up really hard i also had a cylinder 4 misfire code pop for only a small period of time and then it dissapears. My compression is good at about 175 across the board with ~2% variance. I've put new coils and plugs in but it's still happening and I can feel a clear loss in power. Any ideas on where I should start?

 

[iamareios]

Hey guys, so I've been having some issues with my speed 3 lately and I'm struggling with figuring out what it is. So the car runs smooth at idle and during regular driving but as soon as I hit peak boost it breaks up really hard i also had a cylinder 4 misfire code pop for only a small period of time and then it dissapears. My compression is good at about 175 across the board with ~2% variance. I've put new coils and plugs in but it's still happening and I can feel a clear loss in power. Any ideas on where I should start?

Replaced with OEM coil packs? What plugs did you put in? What plug gap was set?

 

[Corey Wilson]

Replaced with OEM coil packs? What plugs did you put in? What plug gap was set?

Yes they were oem coil packs straight from mazda, the plugs were NGK and I don't remember off the top of my head what # but it was happening even prior with the old plugs as it was running fine for a few months and then started doing this only about a week ago

 

[iamareios]

Yes they were oem coil packs straight from mazda, the plugs were NGK and I don't remember off the top of my head what # but it was happening even prior with the old plugs as it was running fine for a few months and then started doing this only about a week ago

It only takes 15mins or less to pull the plugs out to confirm type and gap set. Otherwise a data log would tell you a whole lot more what's going on.

 

[Awafrican]

Logs, need those logs. In theory it could be the PRV starting to fail but without logs it's just a shot in the dark

 

[Corey Wilson]

Logs, need those logs. In theory it could be the PRV starting to fail but without logs it's just a shot in the dark

I'll pull the data logs for it, I just don't want to drive it too much as is.

It only takes 15mins or less to pull the plugs out to confirm type and gap set. Otherwise a data log would tell you a whole lot more what's going on.

Next time I get the chance I'll pull the plugs and update

 

[Awafrican]

Grab an idle and cruising log while you're at it.

I completely understand not wanting to drive it when it's acting funny

 

[Easter Bunny]

The plug gap opened up pull the plugs and regap