KJMS3
Greenie Member
Hello everyone, I'm new here so I'll give a small intro here before I get into it. My name's Keelen, I'm 22 years old and I've had my 2008 Mazdaspeed 3 for a little over a year and a half now. Bought it with around 196000 miles on it bone stock, now with almost 212000 miles, and it was treating me incredibly well until about 6 months ago when this misfire began, and since it's my only running car right now, it's been daily driven since the day I bought it, including now. I like to think I'm fairly well versed in the world of cars and modifying for someone my age, but this car has had me completely stumped, which brings me here, as I've tried everything I can think of.
Everything on the car is from Corksport unless I state otherwise here: 2.5" short ram intake, test pipe, 80mm cat-back, cleaned and flow tested OEM injectors from Graveyard Performance, injector seals and O rings, HPFP, E85 safe HPFP seals, 50/50 VTA BPV, CST4, 3.5 BAR MAP sensor, oil catch can, Tial EWG, 3 port boost controller, polyurethane motor and trans mounts (the set of 3 that CS sells), NGK 6510 plugs gapped at .026". I believe that's everything, and all mods were installed by me at home following CS instructions most of the time for torque specs and tips specific to whatever job I'm doing. I've been tuned by Erik at Dramatune since my first major mod (intake) and have had revisions with every mod from the beginning, and before CST4 I was on an E30 mix. I do also have a catless downpipe on backorder from CS right now. Would also like to add that the EVAP system has been gone through and mostly replaced, since the car threw a CEL for the EVAP system on my way home from buying it and I had to fix it before smog.
Now for background on this misfire. It initially came about when I was K04, stock boost controller, stock MAP sensor, stock HPFP seals (only seals! first mod I did to the car was a HPFP when I got it). Car started misfiring BAD one day so I threw a new set of plugs in it which then caused the "only under heavy load" condition, which I will get into. Sent an email and datalog to Erik to get a second opinion, he recommended new coil packs and a compression test, so I bought a set a new OEM coil packs and sent him my compression test results (which were all good), still misfiring! And nothing in the logs pointing in any direction. So I then moved on to the fuel system and got the E85 HPFP seals from CS since I already had the injector seals and O rings from them and the injectors from Graveyard, still misfiring! Since I had seen oil in the intercooler, my next thought was that my stock K04 had finally given up on me (or was on its way to), so I saved up and got the CST4 with EWG like I had been planning on doing after fixing the misfire anyways, so I figured it's worth a shot! Got my base map from Erik and still misfiring! One thing I found odd, however, is that with the bigger turbo, the car allowed more boost to be made before it started misfiring and gets better MPG when compared to my K04 setup. K04 misfired around 8psi, now with the CST4 close to 12psi. So at that point I began thinking that maybe there's a short somewhere in the wastegate circuit, since right when I start to hear that sweet EWG crack open is when it starts to misfire, so last weekend I put an new ECU in the car, and still misfiring just the same! And now with an ABS code (P2022 if I recall correctly) from the new ECU. Cleaned the MAF today and got another compression test just to double check as well. Compression test number as of 4/14/2026 are as follows:
Cyl 1 - 205
Cyl 2 - 195
Cyl 3 - 205
Cyl 4 - 205
Compression test was done with coolant temp at 135 F. The last test around august 2025 (when I sent the results to Erik) was done hot and yielded similar results. The car drives COMPLETELY normally with no CEL codes until I try to do a small pull and pass that threshold of when the misfire starts (now about 12-13psi boost). When I sit on the misfire it does throw a CEL for most commonly a random misfire P0300, but I have seen P0301, P0303, and P0304 as well since this started. Sometimes it gets some KR while misfiring as well, not always but maybe about half the time, the most I've seen was a little over 3. Also should add that it doesn't misfire at the same amount of boost every time. Sometimes it allows more, sometimes less, so the 12-13psi is just around where it usually does. I've tried experimenting with seeing how the car reacts with higher and lower outside temps, intake temps, and coolant temps, but none seem to make a difference.
That's all the info I can remember to include right now off the top of my head, but if I remember something else I'll be sure to add it. Any questions feel free to ask and I'll reply as fast as I can. I included a datalog, a vid of what it sounds like, and a pic of the plugs which were installed about a month ago when I did the turbo job here as well, the datalog was taken at the same time as the video. In the picture the left plug is cyl 1 and right is cyl 4.
Any help/guidance is much appreciated!!
Edit: Looks like the vid didn't upload since it's a .mov file from my phone, here's a link that should open to it Misfire Vid.MOV
Everything on the car is from Corksport unless I state otherwise here: 2.5" short ram intake, test pipe, 80mm cat-back, cleaned and flow tested OEM injectors from Graveyard Performance, injector seals and O rings, HPFP, E85 safe HPFP seals, 50/50 VTA BPV, CST4, 3.5 BAR MAP sensor, oil catch can, Tial EWG, 3 port boost controller, polyurethane motor and trans mounts (the set of 3 that CS sells), NGK 6510 plugs gapped at .026". I believe that's everything, and all mods were installed by me at home following CS instructions most of the time for torque specs and tips specific to whatever job I'm doing. I've been tuned by Erik at Dramatune since my first major mod (intake) and have had revisions with every mod from the beginning, and before CST4 I was on an E30 mix. I do also have a catless downpipe on backorder from CS right now. Would also like to add that the EVAP system has been gone through and mostly replaced, since the car threw a CEL for the EVAP system on my way home from buying it and I had to fix it before smog.
Now for background on this misfire. It initially came about when I was K04, stock boost controller, stock MAP sensor, stock HPFP seals (only seals! first mod I did to the car was a HPFP when I got it). Car started misfiring BAD one day so I threw a new set of plugs in it which then caused the "only under heavy load" condition, which I will get into. Sent an email and datalog to Erik to get a second opinion, he recommended new coil packs and a compression test, so I bought a set a new OEM coil packs and sent him my compression test results (which were all good), still misfiring! And nothing in the logs pointing in any direction. So I then moved on to the fuel system and got the E85 HPFP seals from CS since I already had the injector seals and O rings from them and the injectors from Graveyard, still misfiring! Since I had seen oil in the intercooler, my next thought was that my stock K04 had finally given up on me (or was on its way to), so I saved up and got the CST4 with EWG like I had been planning on doing after fixing the misfire anyways, so I figured it's worth a shot! Got my base map from Erik and still misfiring! One thing I found odd, however, is that with the bigger turbo, the car allowed more boost to be made before it started misfiring and gets better MPG when compared to my K04 setup. K04 misfired around 8psi, now with the CST4 close to 12psi. So at that point I began thinking that maybe there's a short somewhere in the wastegate circuit, since right when I start to hear that sweet EWG crack open is when it starts to misfire, so last weekend I put an new ECU in the car, and still misfiring just the same! And now with an ABS code (P2022 if I recall correctly) from the new ECU. Cleaned the MAF today and got another compression test just to double check as well. Compression test number as of 4/14/2026 are as follows:
Cyl 1 - 205
Cyl 2 - 195
Cyl 3 - 205
Cyl 4 - 205
Compression test was done with coolant temp at 135 F. The last test around august 2025 (when I sent the results to Erik) was done hot and yielded similar results. The car drives COMPLETELY normally with no CEL codes until I try to do a small pull and pass that threshold of when the misfire starts (now about 12-13psi boost). When I sit on the misfire it does throw a CEL for most commonly a random misfire P0300, but I have seen P0301, P0303, and P0304 as well since this started. Sometimes it gets some KR while misfiring as well, not always but maybe about half the time, the most I've seen was a little over 3. Also should add that it doesn't misfire at the same amount of boost every time. Sometimes it allows more, sometimes less, so the 12-13psi is just around where it usually does. I've tried experimenting with seeing how the car reacts with higher and lower outside temps, intake temps, and coolant temps, but none seem to make a difference.
That's all the info I can remember to include right now off the top of my head, but if I remember something else I'll be sure to add it. Any questions feel free to ask and I'll reply as fast as I can. I included a datalog, a vid of what it sounds like, and a pic of the plugs which were installed about a month ago when I did the turbo job here as well, the datalog was taken at the same time as the video. In the picture the left plug is cyl 1 and right is cyl 4.
Any help/guidance is much appreciated!!
Edit: Looks like the vid didn't upload since it's a .mov file from my phone, here's a link that should open to it Misfire Vid.MOV
Attachments
Last edited:
