2002 Suburban started stumbling on warm idle, then pinging on start, then clattering (valve train) on start. Oil pressure was good, new oil, new filter. Checked numerous forums and replaced plugs w/ new 41-110s (vs originals which there had been a Bulletin issued by GM to replace w/ the newer, smaller gap plugs); new wires. Cleaned TB plate and IAC solenoid, cleaned MAF sensor, new fuel filter, checked and cleaned PCV valve (which is cleanable as it's a simple small orifice type w/o any 'valve' as recommended as a replacement by yet another Bulletin). New oil was Amsoil 5-30 XL..ran same oil for last two years w/o any problem) and new appropriate Amsoil filter. Idle problem got progressively worse, and oil gauge started showing high pressure on start (up in the 70 psi range) then settled down to about 60 during driving), but still shoots right up on even a warm start like the pump is pushing too much oil. Took to a local mechanic who found intake manifold pressure/vacuum okay, fuel pressure okay, but cylinder pressure on #1 cyl. low and its new plug oil fouled (the old one coming out during the change out was fine), and he drove it around stop-and-go till he started getting a check engine code of P0172 Bank 1 Rich. Mechanic said this has been typical of these 'Fantastic Plastic Engines" and said it's basically a shot engine (w/ one cylinder leaking oil and fouling the plug), to pick up some oil additive that plugs internal leaks, and 'run it till she blows' and replace the engine. Not what I think of as a 'solution'. I have another Suburban w/ the 5.7L gas that's been flawless for years, has 327K miles, and still runs strong. These 5.3L replacements seem to be notoriously troublesome, and GM should make it right on their oil flow/consumption/blowby problems.

This truck has had nothing but problems. It was returned the first week for , 1. Weak braking 2. A/C inop. 3. Air vents broken, 4. Horn inop. They did repair the A/C bt claimed no problem found with the others. Back 4 moths later, Brakes, Steering column, A/C, Horn, Battery. Well it goes on, Now it is using coolant, stalls, rattles and runs real bad in cooler weather. Probably an intake gasket!! Steering shaft shot again, horn still bad, 3rd battery. It is on its 3rd battery, A/C still weak, service engine light pops on and off. Leaks coolant, steering clacking. They lost the corvette sale, I'll try a 350Z and see if they can build em right and give better service.