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Discussion Starter #1
I have a 2011 3.6l Automatic w/153,000 miles on it.
The car started running extremely bad and had codes that indicated timing issues. After replacing all the timing chains & related components, the car run exactly the same but the codes went away. Then doing more diagnosing the reason the car still runs so bad, a crankshaft Position sensor indicated to be bad. After replacing the sensor nothing changed & the car still runs just as bad as it was running before replacing the parts. So after more diagnosing, it indicated low fuel pressure from the High Pressure Fuel Pump. After replacing it, the car now runs just a very little bit better, but still won't run long enough to drive. So now, there not any codes or check engine light on so I'm thinking because the car can't be drove, it's the reason that the car won't set a code or turn on the check engine light. I've even tried running the car while on the lift to simulate driving. But the car won't run good or long enough to do that. All parts replaced are AC Delco. I have a hard time thinking it's in the timing chains or one of the parts that's been replaced because the car runs exactly like it did prior to replacing the parts. I would like to know what to check next. Thank you.
 

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Discussion Starter #2
What's the chance it could be running like it is because of the Reluctor Wheel moving that GM has a TSB on?
 

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I haven't seen or heard of a recluctor on a crank shaft or a cam shaft, a reluctor is more of a speed sensor item. The Camshaft and crankshaft sensors sense the lobs of the shaft. But I am not a mechanic nor have I disassembled an engine.
When the mechanic was working on your engine did he happen to look at your intake valves? If the valves get carbon buildup, they may stick and not seat properly, cause all sorts of unexplained drivability issues. My neighbor has an Acadia with 175k on it, his mechanic says his has a cocoon of carbon buildup on his valves. When his starts , it sounds terrible.

After cleaning the VVTs, if you problem doesn't go away, check your valves. A good cleaning will help anyway. Always use Toptier gas and run techron concentrate to do a good cleaning at the very least.

 

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Ok I see where they reference the reluctor in the timing. See page 161-162.
I believe the sprocket should have been checked when the covers were off. I haven't heard of many of these going bad.



 

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I haven't seen or heard of a recluctor on a crank shaft or a cam shaft, a reluctor is more of a speed sensor item. The Camshaft and crankshaft sensors sense the lobs of the shaft. But I am not a mechanic nor have I disassembled an engine.
There's a reluctor wheel on the crankshaft too, that is what the crank position sensor reads for the timing signal. The only times I've ever seen them fail on an LS V8 is usually on motors that have been taken apart, either bent in the process or the shop that built the motor didn't tack weld it on to the crank well and it came loose. Can't recall any instances on these motors.

OP, never had to mess with the crank position sensor but is it in a location where you can get a scope in the hole? Sometimes if the reluctor is bent badly enough you can observe the wobble while turning over the motor. Also does the tach work when it runs?
 

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A bad head gasket can do much the same with coolant going into the one or more cylinders and interfering with combustion. I had a 1998 Tahoe with the V-8 and at 67,000 miles it acted like it had too rich a fuel mixture or one of the emissions components was failing. Spend $1500 at 3 garages and two dealers and no one could determine what was causing the problem. At around 80,000 miles there was noticeable coolant loss and then it was obviously a problem with the head gasket. I replaced it with an aftermarket head gasket that was much better made. For some reason manufacturers routinely use cheaper gasket material for the head.
 

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Discussion Starter #10
Ok. Still setting P2097 & P0420 codes after installing timing chains and everything associated with tune up and related parts by AC Delco, OEM Converters was replaced with a cheap set of catalytic converters and new oem 02 sensors was installed. Car runs great now and gets good gas mileage. Replaced cheap catalytic converters with Davico Catalytic Converters. Still the same codes are being set. What's the chance that the catalytic converter or converters are still setting the codes? What else could it be that is being over looked?
 

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Ok. Still setting P2097 & P0420 codes after installing timing chains and everything associated with tune up and related parts by AC Delco, OEM Converters was replaced with a cheap set of catalytic converters and new oem 02 sensors was installed. Car runs great now and gets good gas mileage. Replaced cheap catalytic converters with Davico Catalytic Converters. Still the same codes are being set. What's the chance that the catalytic converter or converters are still setting the codes? What else could it be that is being over looked?
Does it have Cali. or NY emissions ? Under hood sticker will say if compliant in CA. Cheap convertors usually are Federal and not CA compliant and they will set cat. inefficiency codes P0420. Went through that with my brothers Impala, his garage put in the wrong cats, federal not CA and his car was NY / NJ compliant. CA compliant are more expensive and sometimes are OEM only.
Engine-codes.com will give you some diagnostic suggestions.
 
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