Out of ideas - Timing Freeze frame codes P0335, P0340, P0342

[Luis Alves]

I own a 2008 Corolla. 152ZRE engine code 2ZR-FE

Started getting a Freeze code P0335, but engine ran well, fuel economy still good as before. Serviced vehicle (every year ~10,000km, oil, Castrol Edge 5W30 and oil filter replaced), inspected old oil for foreign objects (metal fillings or anything else, all smooth nothing in the oil tray, checked oil filter as much as I could, all looks good.    

Checked crank case sensor with multimeter, checked wiring at sensor end and ECU end for continuity, checked fuses and wiring harness for breaks or loose wires, all  all good. Reset the Error code, but same code kept returning.

Also suspected the ECU. Opened ECU to look for blown or bulging capacitors or any burn marks, all looks good. Closed it and started engine, all good, next day couple of Km's later P0335 back on. same behavior as before.

The symptoms are; when driving there would be a small jolt, hardly noticeable when the engine light came on. This would happen at random times, (Town driving, Highway driving, sometimes reversing out of the garage, at time 2 minutes of driving other times 40 minutes of driving) could not point out any specific driving condition that would throw the error code.   

I started recording the freeze frames to see if there were any abnormalities that could point me in the right direction. (see attached spreadsheet) 

A week ago the car started to feel a little rougher but never cut out, I hooked up the code reader and a new code came up (P0340 - Camshaft Position sensor A Bank 1 or single sensor).

Car still drove no hesitations, about 10 km's down the road I noticed a gentle but more noticeable jolt that would come and go for a few seconds and then all good for a few minutes and then returned. I stopped the vehicle and checked the error codes. Another code came up (P0342 - Camshaft position sensor A Circuit Low Bank 1 or single Sensor).

I was about 10 km's, started the engine and noticed at idle, the revs would climb and drop between 400 RPM to 800 RPM, in a wave pattern, would do this for about 20seconds then return to 600 RPM, so decided to carry on as there were no knocks or other sounds coming from the engine.

Got home the car was still behaving in the same manner, revs climbing and dropping for a few seconds and then fine for a few minutes, no abnormal sounds from the engine.

The engine never cut out. Tested the crank sensor and the cam sensors( bank A and Bank B both ends of the camshaft.) All good.

Out of ideas at this stage, so I decided to open the valve cover to see if I could find a possible cause.

Timing chain tension felt good, small amount of slack between compression strokes, nothing like before.

Removed inlet camshaft, noticed small amount of wear marks on the bearing just behind the VVTI gear, felt smooth with no indents. Looks good for a 160 000 km's on the clock 

Removed exhaust cam shaft and noticed bad wear with deep grooves in the bearing behind the VVTI gear. ( see attached image)    

The deep grooves in the bearing run alongside the oil journal that feeds the oil pressure to the VVTI gear.

Inspected the cam shaft at the oil journal in line with the grooves on the bearing and noticed a rough edge that I suspect has been causing the grooves in the bearing.     

Questions:

Could these grooves in the bearing be causing the Error codes?

Can the Cam be polished to remove the rough edge without affecting its performance?  

Could the ECU be faulty?

Could VVTI exhaust Phaser be faulty and caused the grooves in the bearing , or foreign object cause the groove in the bearing and possibly damaged the VVTI phaser?

Anything noticeable on the freeze frames?

Anything that I missed, that could be causing the issue? 

 

 

    

Corolla Freeze Frames.xlsx

Edited December 4, 2021 by Luis Alves
edit, extra information and picture