I have 2007 CX7 that I have just replaced the timing chain. The car starts as normal but the engine light has come on with a P0300 and I cannot pin point what the issue is.

I have a small scanner that gives me access to some data but I have not much idea what it means.

From my research, it looks like my upstream O2 sensor is bad, could anybody help me confirm this?

The graph is the RPMs (red) to O2 sensor voltage (green) relation. Also the freeze frame data shows the fuel trim %.

Thanks in advance

 

How did you adjust/align the camshaft & crankshaft when replacing the chain? Timing could be a tooth out.

 

I set the camshaft timing tool on the camshaft grooves as well as put the engine on TDC by rotating the crankshaft and putting its counterweight against the timing peg/bolt, and I match the hole on the crankshaft pulley with the hole on the timing cover. I believe I did it right but it could be a possibility.

I little more background on this. We bought this car knowing it had some misfiring issues, it turns out it had several burnt valves. Heads were taking off and sent to a machine shop. Valves were replaced as well as heads resurface and tested. Since we took the heads apart, we also replaced the VVT actuator on the intake cam, which I learned tend to be an issue on this engines. There was a P0016 code but we replaced the crankshaft and camshaft position sensor as well as put the crankshaft sensor on the 20th tooth of the pulley according to what I found. I reset the light for the p0016 and hasn't come back yet.

I've done a lot to make sure this engine's timing is where it should be but I'm just lost. Which is why I decided to look for another opinion.

Thanks for any help you can provide.

 

Most likely your problem are clogged injectors. Since the head was off, what seals did you use for the injectors ( injector and the head)? And while the injectors were out, did you inspect a paper filter in the injector?

Do you feel the misfire how bad it is? There could be lots of things. I would need more information as I went thought something like that. What did you use for seals between the rail and injectors?

 

Yikes, I did not inspected the injectors. I did not know they had a filter. Also, did not replace the seals from the injector to the head. The injectors were never separated from the rail. The misfire is not bad, the car starts normal a little higher on the rpms (2000) but after a few seconds rpms drop to about 700-750 and it runs fine no rough idle. I think is only once accelerate that the misfire happens. If you drive it, as long as you accelerate slowly no issue, but if you step on the gas pedal hard to try to take off you can tell there is an issue.

Also, I just started the car this morning to see if any other codes appeared and sure enough a P0016 and P2178 (System to rich of idle bank 1) are there.

 

P0016 is either Cam or Crank sensor.

Did you replace the VVT - Variable Valve Timing sprocket?

 

I have replaced the Crank and Camshaft position sensors. Code still appeared.

I did replace the VVT sprocket.

 

the P0016 is the code for CMP and CKP correlation. First I would check what is your timing chain slack. Remove the oil cap and feel the chain with your finger. there should not be any chain free play. If there is slack then you need to investigate more. Next will be to check your timing by installing the timing tools. you need to verify that your crankshaft balancer tooth is aligned with the sensor.
Also, did you inspect the camshaft caps and the first cap filter to the VVT solenoid? is your VVT locking?

Add a bottle of injector cleaner. Most likely you have a plugged injector? Here is an example of the microfilter.
https://www.aliexpress.com/item/4000...66a09ffc0ee-34
the filter screen is a paper mesh. overtime disintegrates and plugs the injector. if you ever remove the rail this needs to be replaced with stainless steel.