Highest Mileage cars

I've had mine for over 16 months and have 20,000 miles on it. for a variety of reasons I didn't drive it much the last few months so it should be more like 25k but it works in my favor since I'm way ahead of pace for the lease miles. anyhoo the only real problem I've had is with the hfv6. there are a number of issues that have to do with crankshaft and camshaft timing sensors and their sensitivity. these show up as reluctor problems, the infamous "shim" issue - too much camshaft endplay in the heads - and I believe timing chain stretch as well. I would not necessarily ding the CTS for this since it is a corporate motor based on the old chevy v6 redesigned by Holden, and it is used in many gm cars and crossovers. the problem with mine occurred at ~12k miles. as far as the car itself goes, I think the designers may have overextended themselves with the large vista sunroof. it is heavy and takes up a lot of roof structure, with the result of being sensitive to alignment and causing noise - both wind noise and creaking. other than that I'm doing fine.
rg

jtallequipment said:

Thanks, You are probably right.

By the way when I saw reluctor in your prior post I thought it was a typo. What is a reluctor?

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the hfv6 has 4 overhead cams, 2 for intakes and 2 for exhausts. these are timed for actual intake and exhaust events relative to piston position and rpm. the ecm needs to know exactly where the crankshaft and all 4 camshafts are at all times (plus how fast the crankshaft is rotating) as feedback for the vvt functions. these shafts are usually either steel or iron, and typically forged. the sensors can be of various types and technologies, and holden/gm designers decided to use a magnetic system that uses variable reluctance to trigger a sensor. there are relatively soft iron toothed rings pressed on to the crank and cam shafts to activate magnetic sensors so the computer receives electrical pulses related to the individual shaft positions. one problem is that the soft iron reluctor ring can slip on the shaft. also if the camshaft is allowed to travel end-to-end too much the sensor will get a weaker signal. the ecm runs continuous checks among the 5 signals to make sure the levels and timings are valid. if any of the cam drive chains stretches more than some practical limit the ecm will complain about the timing events. usually it ends up being a singular event but the new ecms are required to catch possible cylinder misfire events for pollution control so this type of occurrence can be caught as a misfire code. then the check engine light is set, even though the motor continues to run normally.