Knocking / Pinging noise resolved P2187 P0300 P030_ Misfire

[CX-7Pilot]

Okay, the backdrop: 2007 CX-7 that had a remanufactured engine swap done a year and a half ago. About 20,000 miles on the new engine. Old engine had bad turbo and valve/VVT issues and was burning oil.

FF to 12 months ago and began to notice exhaust leak at the exhaust manifold to turbo joint. Tried to re-torque the exhaust and snapped the stud on the turbo. Also getting P0126 (coolant running too cold and not coming up to temp reliably)

FF to about a month ago: Noticed a knocking/pinging sound when I was getting into boost at about 3000 RPM and under a load. The sound can best be described as about 10-15 rattle paint cans simultaneously being shaken from under the hood. Could also pass for marble shaking around randomly. This would only occur under moderate to high load with boost.

Since the ECU was giving me codes P0302 and P0300 after about a week or two of this new noise I changed the spark plugs out and changed the coil to another cylinder to make sure it wasn’t that. It wasn’t so I finally decided to have a mechanic pull the turbo off and fix the exhaust leak. He was also under the suspicion that it was the exhaust leak causing the lean code and misfire. WRONG. The exhaust leak didn’t fix the knocking/detonation. Without spending more, I have him stop there since he only wanted to replace the injector(s). He says the injectors would be his next step in trouble shooting since there was nothing else to really go on.

I get the car back with the exhaust leak fixed and call a local mobile mechanic that did some work for my brother. I had him pull the intake manifold off along with the injectors. I had all kinds of carbon build up on #2 injector. Had them all professionally cleaned at the local DR. Injector shop and flow tested. #2 had 20% flow restriction and after cleaning all working as should. The injector shop also said that a seal was missing from the injector. This was intersting because the injector had all kinds of carbon/black buildup all the way up the base of it (outside the engine part). Went to the Mazda dealer for the $31.00 seal :/

While the intake manifold was off I took a close look at the valves to see how they were doing. They were FILTHY! I’ll try to add pictures later, but rest assured they were really carboned up. I’m suspecting that the residual oil from the intake parts like intercooler and EGR blew through to the new engine and left all of the deposits. The EGR valve pipe (Stainless pipe under the manifold) that was left with easy access was also nearly blocked. (Thanks previous mechanic!) I cleaned the valves up a little with Seafoam and a toothbrush while everything was off to let it soak before the “real” treatment that would come later. Also cleaned the throttle body that was also dirty with a film of baked on oil.

Had injectors installed and took it for a drive. Runs GREAT! No knocking or detonation under boost! I get back to the house after my verification run that it was the injector causing problems and do the infamous Seafoam treatment that can be found on YouTube.

https://m.youtube.com/watch?v=ILjk8hxrDDE (for the rate of flow/reving the engine)

https://m.youtube.com/watch?v=VJMWZDlUMog (For where the hose is) I used a rubber tube with funnel on the end to slowly pour in the Seafoam and went back to the inside to do the reving since I didn’t have a helper.

Lots of crud came out of the exhaust. Took a few miles of driving before everything cleared out. I reset the ECU and so far it runs like a champ. No issues and no codes.

Summery: The CX-7 is quite a bit different than any other car I have owned. The Direct Injection system is something new for me and now I have an appreciation for how big of a bearing it has on how the engine runs. I think my next mod will be the HPFP (High Pressure Fuel Pump) and a simple tune (Versa Tune). I might change out the intake as well. Also looking at the EGR delete kits. Hope this post helps someone scratching their head at the rattling noise under the hood.

[speed23]

Well done solving your issues.

[Fstrnyou]

EGR delete and Catch Cans...