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**60dgrzbelow0** · 06-22-2009, 08:34 PM

I'm not familiar with all the secondary gear sets on the overhead valve engines (including where and how many crankshaft/camshaft position sensors there are)... but from personal experience...when an engine has that many starts and stops and around 120,000 hard miles on it, the standard timing set stretches out of shape pretty bad and the gears lose their precision from wear.

All ECU controlled engines take positional readings via an assortment of sensors as the cam(s) and crankshaft rotate inside the engine and uses this information from moving Reluctor Rings, Magnets and Hall Effect devices to figure out when and how long to open the fuel injectors and when its best to fire the spark plugs in time with just the right amount of BTDC to efficiently power the engine. If your Timing Set is badly worn...it will cause things to read wrong essentially because the worn chain and gears attached to the cam and crank shafts are not actually where they ought to be when the sensors pick up their out-of-wack locations. The ECU doesn't care, because when the sensor reading comes through, it just provides fuel and spark and it will not calculate any mis-positions from a badly worn Timing Set.

Worse than that, the annoying rumbling and sputtering...(And Shaking Like a Chihuahua Sh***ing a Peach Pit) is the very real possibility of the chain "Jumping Timing". Very bad things happen inside the motor if this sadly takes place....Valves open when they should close, pistons smack the valves and self-destruct...it's a total destruction scenario. The only real way to determine the problem is to disassemble the front of the engine with all that that entails and replace the Timing Set with a New One. By now, eBay probably has a Seller who is offering the GM Factory Shop Manuals for your 2000 Monte Carlo and having that set of books can make your life easier should you have to do this work yourself.

There are also special tools needed to do the job and a new Harmonic Balancer Redi_Sleeve repair kit and Timing Cover Seal should be done at the same time. Rarely, sensors that are mounted in the engine block to record the locations of moving things and signal the ECU to that effect can either break or crack inside the engine block and fail to do their jobs as a result. Replacing sensors that get exposed during the change of the Timing Set makes good sense. Here is a link to the generic Timing Sets available for pricing...but your local Auto Parts Stores carry them and will either loan or sell you the tools needed to make the fix in most cases. Good Luck with the repairs!

http://www.thepartsbin.com/catalog/?N=1588+9535+4294963909+4294962181

**60dgrzbelow0** · 06-22-2009, 08:47 PM

As for the Fuel Injectors...It might be worth your while to pay a local auto shop to do an "OTV" On The Vehicle Pressure Cleaning of them. Usually, the mechanic uses several cans of concentrated cleaner that, instead of just pouring the stuff into your gas tank and hoping for the best, will mount a pressure cylinder to your EFI Fuel Injector Manifold and block of the closed system gas lines while the engine essentially runs on a mixture of fuel/EFI Cleaner until the Fuel Injectors start spraying the appropriate style of a fuel efficient "Atomized Mist". If your vehicle runs ragged after this service and having a fresh set of plugs, wires and a good scan from an Actron 9XXX Scanner or similar OBDI & OBDII Scanner for hidden error codes... then your Timing Chain Set returns to the scene of the crime as your culprit.

**monte2k** · 06-23-2009, 12:10 AM

Thx gents,

your posts actually made me feel alot better about the situation as i planned on getn a new timing chain set sometime next week...

that being said, if it doesnt fix it.. well.. i'll go from there i guess...

again, appreciated!

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