CX7..... Help me!!!

Ok guys. I'm new here. So if this is not where this belongs. Let me know. I'll put it where it should be. So I'm completely lost at this point. I have a 2007 Cx-7 (2.3l Turbo). I bought it from my boss a few mommon back. He owned it when there was 47,000ish miles it. Currently has 187,000 miles. When I took possession of the car. Timing was in need of repair. Had stretched chain. So I had everything replaced. Not one part was left out. Let's go back just a bit..... Car sounded like a diesel. Had the ticking sound on start up. As many folks describe with their vehicles. About 5,000 miles before I bought it. He had a misfire in cylinder 4. At that point. My boss replaced all coils and plugs. Few months later. I bought the car. Started misfire again in cylinder 4. So I changed coils and pligs. Immediately after it jumped to cylinder 1. I did the coil swap test. No luck there. At that point I had the timing repair done. Again, replaced everything. once done, it drove excellent. No ticking. No diesel sound. Fantastic throttle response and shifting was on point. No issues. One week after timing job. It started misfire again. Cylinder 4. AGAIN. At that point I decided to remove manifold and do the media blast on my intake valves. My valves were filthy heavy carbon Build up. Once I finished the media blast. The valves looked really nice I reinstall everything hoping that would take care of the issue. It did not misfire continue. I have had the computer in the vehicle checked. everything is communicating as it should so I have no computer issues. I am at a loss. The car is in fantastic condition. I even took it to the dealer when I took possession of the car and had a few recalls fixed on the front suspension so it pretty much has a new front end. Transmission is in great condition. Not to mention the fact I have a lot of money invested into this car as it is. I am taking it to the dealership on Monday. When I called and talked to the service technician. He had told me that given the fact the timing was just done on the car that there is a high likelihood. The timing was not set one hundred percent cor it is possible that is the issue. Can't really be a bent valve given the fact that the car drove fine for a week and then started the same issues after three thousand miles worth of driving. So before I take the car to the dealership. I'm reaching out to the community here and hopes that somebody else has had the same exact issues and maybe has a fix. it's only going to cost me $135 to have them diagnose. After everything I've been through. I am going to just go out on a limb and say what's it going to hurt. I am scratching my head. My cat and O2 sensors are okay so I know that can't be the issue. When I did the media blast I inspected my intake valves for any of them being bent. They were not. I have not been able to look at the exhaust valves so I can't give any information there. Any help would be greatly appreciated guys. I'm not getting rid of this car. I'm in it for the long haul I understand there is a lot of miles on it. But I am dedicated to it and I know once I fix this issue it will be okay. I have already gotten myself prepared to just replace the motor as it is. if I have to do that I will just pull my current motor out and over the course of the next few years I will fix that motor and heck who knows even make it extra special lol. Put it in a crate and keep it for a rainy day. Or a racetrack whichever one comes first. But in the meantime here goes I hope you guys can help.

 

OK, wall of text!
1) when was vvt and timing done? Who did it?
2) did you get a compression test?
3) did youget a leakdown test?

 

A local shop here in Phoenix did the timing. There is a chain of these stores roughly seven of them in our area all together. That's not to say that these guys knew what they were doing. Heck I'm starting to second-guess it. As far as the compression test goes. Unfortunately I was low on compression in cylinder 3. By about 40psi. Granite this test was performed by the same people that did the timing. So I'm going to retest compression tomorrow before I take it to the dealer on Monday. Because honestly it's not that I don't trust their results. I just want to see for myself. Now mind you all this was done about a month-and-a-half ago. And when I got the car back it drove perfectly for a week. I understand that there could be worn seals. However, correct me if I'm wrong. I was under the impression that if in fact there was Worn seals. I would be burning oil. I can tell you that this is not the case at all. Between my oil changes I don't even notice a change on the dipstick at all. Somebody told me that I would be smoking. However I know that with today's cat converters that is not necessarily the true. So I guess there could be worn seals. What other symptoms would I have if I had that issue? I am learning as I go here I am certainly not a Certified mechanic but I can most definitely tear these things down and put them back together. I just need to learn what to look for and what to to expect. and to answer your question about the leak down test when I went to go pick the car up he did not inform me at all about a leak down test being done. And to be quite honest with you. totally slipped my mind. To even ask them if they had done it. Like I stated in my original post I described all of this to the service manager at a local dealer here. Last thing I wanted to do was take my car over there. But I guess if $135 will at least tell me where the misfire is coming from. Then based on everything I have been through so far. I'm going to say it's worth it. However I would really like to figure this out and not do that at all. I just don't have a lot of funds to go and purchase the necessary equipment to do a leak down test. But I probably should do that I suppose. Unless my list of symptoms does not sound like a worn seal. That's where I am hoping you folks can chime in. And help me out. But honestly it seems like I might need to do that.

 

Blowby on the plugs hints it's motor time. A leakdown and compression test after verification of timing is key. Non Mazda shops are notorious for fucking up the timing though.

 

Have you checked your fuel pressure relief valve? I had misfire codes due to lean fuel as the valve was not holding pressure. You could also clean the spill valve.