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SRX
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Discussion Starter #1
I'll try to make this very long story as short as possible. I have a 2004 SRX, 3.6l LY7 engine with 163K on it. Began getting codes related to camshaft position with the MIL on. It was also using 1qt of oil every other fill up and only got 16-17mpg. The only drivability issue was the engine randomly 'dying' for 1/2 a second or so at stop lights, but it would always catch again before dying completely. I decided to try and fix everything at once and be done with it.

Removed the engine and tore it down completely. Reassembled with:

New crank and rod bearings
New rings/honed cylinders (original rings were packed TIGHT with carbon)
New thermostat
New water pump
New oil pump
New timing chain kit from Rock Auto
Rebuilt Cylinder Heads from Odessa on Ebay

When I started it up, it ran very rough and set a code for Bank 1 Sensor 1 O2 sensor circuit shorted. It also had P0300 and 3 or 4 cylinders with misfire codes. After replacing the O2 sensor nothing changed. The misfires appeared to be timing related so I tore into it, again, and carefully redid the timing. After starting it the symptoms were the same, but this time Bank 2 Sensor 1 reference signal low was faulted. Bank 1 compression was around 160 and Bank 2 around 180. I then removed the left cat, which wasn't blocked, changed the Bank 2 Sensor 1 and both downstream sensors. The engine then ran "better" but still had O2 sensor faults and, the random misfire faults. Next I changed the ECM, which fixed the O2 sensor faults and narrowed the misfires down to cylinders 2/4/6.

I am pretty sure I set the timing chains correctly, but have again torn down the front of the engine to try one more time. (no pun intended)

Is there something else that could be causing my problems? Cam phaser, wrong cams, or anything else I can check while I have it apart? I have a Tech2win set-up and verified the cam phasers were moving as commanded, so it seems the chains on the idler sprocket must be off, but...

Any input or Ideas would be greatly appreciated! I'm at the end of my chains. (pun intended)
 

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2004 SRX V6 AWD
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737 Posts
Given the age of your vehicle and the amount of disassembly/assembly, I'm thinking wiring harness/connector problems.
I know that's not much help, but all that jumps out at me.
Keep digging.
 

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'07 - 3.6l SRX RWD, '16 - 2.5l Subaru Outback, '95 - 4.3l S10 pu
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978 Posts
Have you checked fuel trim values? Could be a lean misfire from a vacuum leak.
Since misfires are on one bank I'd check if the injectors and/or coil packs share a common ground or power source.
 

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SRX
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Discussion Starter #4
Thanks for the tip. Yes the connectors and wire loom tubing are all very brittle. I'll keep my eyes pealed for anything that could be causing a short or bad connection. I did clean and reassemble all of the grounds with dielectric grease.
Shovel in Hand!
 

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Discussion Starter #5
n7don-I did in fact look at the fuel trim values, short and long term values were 0, and had been disabled due to being in open loop? All of the injectors were being opened for the same amount of time. Didn't test for a vacuum leak beyond making sure all of the hoses were hooked up.
I'll check the diagrams again and see if there is a common ground, although I did clean them up and reassemble them with grease maybe I didn't tighten one all the way.
I did however find the little spring that pushes on the top of the spark plug in the #2 coil was missing, so that was at least part of the problem.
 

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'07 - 3.6l SRX RWD, '16 - 2.5l Subaru Outback, '95 - 4.3l S10 pu
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978 Posts
I've found by the time I've backed out of the garage the system is in closed loop. How long had the engine been running when you checked fuel trim?
 

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Discussion Starter #7
n7don--Watching on the scan tool it would enter closed loop fairly quickly, then just as quickly revert to open loop, where it would stay regardless of how long I let it run.

I've got the timing set and the engine going back together after a careful inspection of connectors, wiring, gaskets, well everything. Found a tiny nick in the edge of the right head where the lower intake seals by #3 cylinder runner, but any vacuum leak there would have been tiny. Didn't find anything else wrong.

Right now I'm hoping I didn't get the timing set correctly, probably the secondary chain at the left bank idler sprocket, at that everything will work correctly now. Fingers crossed!
 

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Discussion Starter #8 (Edited)
Well, after putting everything back together I've still got the same problem, but with a new clue. The engine doesn't run as rough, probably due to replacing the #2 coil with the missing spring. Now however the ECM is faulting P2247, along with all of the misfire codes. I've checked the voltages, for shorts to ground, and even have taken the wires out of the plastic looms from the HO2S plug to the ECM plug and haven't found anything wrong.
Now I'm thinking that the new HO2S is faulty when it gets hot. That would explain why it goes into closed loop at first and then open loop for the rest of the time. I've got a new one on order, Bosch this time, not Chinese. Sure hope this fixes it as I'm out of ideas...

IMG_0584.JPG
 

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Did the new O2 sensors fix your misfires? I am having the same exact issues as you after replacing the engine except on bank 1 (cylinders 1,3,5 misfire)
 
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