Interference engine

[dtech]

Usually see a cam/crank correlation codes way before you'd have a timing chain failure due to wear, at least with modern engines. GM 3.6's would do this. They they actually reprogrammed the PCM's to allow a greater variance between the crank and camshafts, because it was such an issue. Once your CEL came on again, you got a set of chains under warranty (up to 120,000 miles).

reminds me of what some mfgs do when too many misfire codes were detected - simply raise the cel threshold - I think Hyundai did this on their crappy Theta II engine.

Was the chain replacement the result of a class action against GM or did they step up and do it voluntarily ? pre Mary Barra era GM was not known for being overly customer friendly.

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[I_smell_like_diesel]

reminds me of what some mfgs do when too many misfire codes were detected - simply raise the cel threshold - I think Hyundai did this on their crappy Theta II engine.

Was the chain replacement the result of a class action against GM or did they step up and do it voluntarily ? pre Mary Barra era GM was not known for being overly customer friendly.

I don't know the specifics on that off hand. I think the lowest mile engine I threw chains in was 38,000 miles. They would commonly not last past the powertrain warranty, even after open the tolerance on the Cam/Crank correlation limits. I imagine they had a lot of pissed off customers, that bearly sweaked past the warranty and probably put the squeeze on GM.