1991 Tahoe 5.7l 138,000

Problem - ocassional loud pop and white smoke rises from hood at start up. No codes.

This has got me stumped. Pop is like firecracker, once. I have no idea where the white smoke many come from. ANY IDEAS ?

Thanks

does it happen when you give it gas or just at idle

Your engine is backfiring which may be cured with a good tunup as long as it only happens when you start up. The white smoke is from carb.

superman, it does not occure when engine is running. Just at cranking. Short cranking. Pop within 1-2 seconds from strat of turn over. It is the white smoke that has me perplexed.

No I don't think tune-up. 100,000 mile plugs replaced at 100,000 along with rotor cap. And just passed California dynometer smog test (toughest in country I believe). No carb, it is fuel injected. The CSFI fuel injector have known problems (documented in Chevy TSB) OK, the wires are original and should be replaced but that does not explain the white smoke waffting our from under the hood.

Mistery...