Long story short: Found 1) practically non-functioning timing chain tensioner. 2)Timing chain advanced on crank 3 sprocket teeth and 3) Both cam phasers stuck unlocked and slack in oil pump
Short story long:
Sister's 2012 equinox 2.4 with 145k miles with severe (and I mean seveeere) engine shake, rattle and roll. It only ran when cold, and got an almost immediate notification that "engine power reduced" It would chug along in like first gear only I think and have like half a horsepower. Could not drive uphill. it just kinda grumbled and stuttered along. It threw 11 codes for cam position, misfire, fuel pressure and whatever. Was told by the dealer that it needed a new engine, costing upwards of 8 grand.
Under the valve cover everything looked ok, that is to say, no obvious damage and a seemingly tight chain. We ran it without the cover and I was surprised at how slow oil seemed to accumulate there. Perhaps normal? Anyway, could not find the source of the rattling and banging. Cold compression test read like 255 psi +- 5 on all 4. Borescope in spark plug holes showed no obvious damage. Removed the pre-cat o2 sensor and ran it to see if perhaps a plugged cat was stopping exhaust, but there was no change in engine performance. Bought a $200 high pressure fuel pump, since at least one code was for fuel pressure. No change. Interesting that both the old and new high pressure fuel pump became VERY hot after about 30 seconds of engine running. I started thinking perhaps there was some ECM malfunction happening since you know that they couldn't find a more inconsiderate, counterintuitive, corrosive environment to put the brain of the vehicle than right above the hydrogen sulfide gas-producing battery in that 200+ degree engine compartment... but I did more digging. I did minor research on these engine timing issues, enough to know there were variations between engines and years and just went in. Cam reluctors seemed to be in their proper place. I then checked timing by removing the alternator and compressor belt, crank pulley and front cover/oil pump. I swear the camshaft/chains/crank and balance shaft timing marks lined up on the second turn. I just figured they would, I didn't find out until later that that the colored links and sprocket timing marks line up only once every 40 revolutions or something, funny I had some good luck there!
Here's where it gets interesting, at first I thought it was timed right, as the colored links of both the timing chain and balance shaft at the crank were at the same mark on the crank sprocket, and the cam sprocket marks were paired with their colored links, so I thought it was not a timing issue. I then noticed the darn washer I have on the crank sprocket, paper-thin, sharp as a razor, oil stuck it in place and I almost cut myself removing it to find another timing mark underneath it on the sprocket. I then saw that the timing chain advanced on the crank 3 teeth. I would figure the crank would advance on the chain from engine rotation, though. I found a creaky, kinda working tensioner for both timing and balance chains. Guides all looked like minimal wear, with the exception of the black front one which lost a chunk of the hook portion. I decided to put everything back in time and see if it runs before buying any new parts. After assembly, I turned the crank by hand and got a chain slack and snap between the cams. More research and some videos online showed me this was a cam phaser stuck open. I removed them and opened them and found that indeed they were both unlocked, (they're supposed to be locked when engine off or lower rpms) and the spring loaded locking plug didn't really slide in its bore freely. I did a little cleaning and got them locked in place, and put them back on the cams and it looked good. I reused the unuseable bolts as this is still a trial. Engine runs like a watch now. Battery was disconnected for a couple of days, so everything reset. Before doing all this, I tried a reset by battery disconnect and upon startup I would almost immediately get like 5 codes, but now none. I drove it up to normal speed, no "reduced power" notification and zero codes. I guess I don't need to do any computer relearns. I am concerned about oil pressure being the original problem, but will figure the best way on checking that out soon enough. I am concerned that the oil pump might be bad as it seems like there is some slack and play in the center part where the crank pulley goes through. Not sure if that should be there. I fully warmed up the engine and found compression testing all 4 cylinders to be 265-270 psi. I would have figured with a crank mismatched by three teeth, there would have been a significant loss of compression, and I also was worried about bent valves, but I guess 3 crank teeth are not enough, which makes sense because the phasers sure can change timing by quite a bit. Happier than a pig in mud am I. One kinda obvious pointer I'd like to give is that the crank keyway is supposed to be at 12 o'clock, BUT that is in relation to the engine, which is tilted back a few degrees. It will not be at 12 o'clock position relative to the level floor. I hope this helps someone sometime.
Short story long:
Sister's 2012 equinox 2.4 with 145k miles with severe (and I mean seveeere) engine shake, rattle and roll. It only ran when cold, and got an almost immediate notification that "engine power reduced" It would chug along in like first gear only I think and have like half a horsepower. Could not drive uphill. it just kinda grumbled and stuttered along. It threw 11 codes for cam position, misfire, fuel pressure and whatever. Was told by the dealer that it needed a new engine, costing upwards of 8 grand.
Under the valve cover everything looked ok, that is to say, no obvious damage and a seemingly tight chain. We ran it without the cover and I was surprised at how slow oil seemed to accumulate there. Perhaps normal? Anyway, could not find the source of the rattling and banging. Cold compression test read like 255 psi +- 5 on all 4. Borescope in spark plug holes showed no obvious damage. Removed the pre-cat o2 sensor and ran it to see if perhaps a plugged cat was stopping exhaust, but there was no change in engine performance. Bought a $200 high pressure fuel pump, since at least one code was for fuel pressure. No change. Interesting that both the old and new high pressure fuel pump became VERY hot after about 30 seconds of engine running. I started thinking perhaps there was some ECM malfunction happening since you know that they couldn't find a more inconsiderate, counterintuitive, corrosive environment to put the brain of the vehicle than right above the hydrogen sulfide gas-producing battery in that 200+ degree engine compartment... but I did more digging. I did minor research on these engine timing issues, enough to know there were variations between engines and years and just went in. Cam reluctors seemed to be in their proper place. I then checked timing by removing the alternator and compressor belt, crank pulley and front cover/oil pump. I swear the camshaft/chains/crank and balance shaft timing marks lined up on the second turn. I just figured they would, I didn't find out until later that that the colored links and sprocket timing marks line up only once every 40 revolutions or something, funny I had some good luck there!
Here's where it gets interesting, at first I thought it was timed right, as the colored links of both the timing chain and balance shaft at the crank were at the same mark on the crank sprocket, and the cam sprocket marks were paired with their colored links, so I thought it was not a timing issue. I then noticed the darn washer I have on the crank sprocket, paper-thin, sharp as a razor, oil stuck it in place and I almost cut myself removing it to find another timing mark underneath it on the sprocket. I then saw that the timing chain advanced on the crank 3 teeth. I would figure the crank would advance on the chain from engine rotation, though. I found a creaky, kinda working tensioner for both timing and balance chains. Guides all looked like minimal wear, with the exception of the black front one which lost a chunk of the hook portion. I decided to put everything back in time and see if it runs before buying any new parts. After assembly, I turned the crank by hand and got a chain slack and snap between the cams. More research and some videos online showed me this was a cam phaser stuck open. I removed them and opened them and found that indeed they were both unlocked, (they're supposed to be locked when engine off or lower rpms) and the spring loaded locking plug didn't really slide in its bore freely. I did a little cleaning and got them locked in place, and put them back on the cams and it looked good. I reused the unuseable bolts as this is still a trial. Engine runs like a watch now. Battery was disconnected for a couple of days, so everything reset. Before doing all this, I tried a reset by battery disconnect and upon startup I would almost immediately get like 5 codes, but now none. I drove it up to normal speed, no "reduced power" notification and zero codes. I guess I don't need to do any computer relearns. I am concerned about oil pressure being the original problem, but will figure the best way on checking that out soon enough. I am concerned that the oil pump might be bad as it seems like there is some slack and play in the center part where the crank pulley goes through. Not sure if that should be there. I fully warmed up the engine and found compression testing all 4 cylinders to be 265-270 psi. I would have figured with a crank mismatched by three teeth, there would have been a significant loss of compression, and I also was worried about bent valves, but I guess 3 crank teeth are not enough, which makes sense because the phasers sure can change timing by quite a bit. Happier than a pig in mud am I. One kinda obvious pointer I'd like to give is that the crank keyway is supposed to be at 12 o'clock, BUT that is in relation to the engine, which is tilted back a few degrees. It will not be at 12 o'clock position relative to the level floor. I hope this helps someone sometime.
