smithsclassic

I have a 99 Chevy Tahoe 130K miles, when trying to start the engine occasionally I get a pop and white smoke on top of the engine. Otherwise runs great. Replaced plugs, cap and rotor, checked for leaks around base of throttle body. Had vehicle to Chevy dealers garage three times no codes they can't find theproblem. I have owned this vehicle since it was new. Any help would be appreciated.

Thanks,

Mark

jlenkows

Check the timing.

Many moons ago, I owned a Ford -- and if you disconnected the battery overnight, when you reconnected it and started the engine, it re-tuned itself and suto-adjudted the timing.

At least that's what 2 dealers told me.

It always ran GREAT after I did that.

ZX1100F1

Usually this condition is the reult of sticking valves from poor quality or contaminted fuel.
First you will want to buy your gas at a different station, then I would recommend adding several (4-6) 12oz bottles of Chevron Techron Fuel system cleaner to a full tank of fuel and drive it out and also clean the unduction system with a spray type top engine cleaner.

If you don't get this condition to stop it could damage the valves or cam or head.

Slammed

This article was written for the camaro/trans-am, but the principles apply to the Tahoes as well. Do this twice a year and you'll be golden, though some people do it more often and some less.



The Problem Areas
For the intake manifold:

This is the item that sits on top of the block and allows the air and fuel to mix before combustion. As can be imagined, left-overs accumulate on the inside of this aluminum item, and can reduce the efficiency of combustion due to contamination (lower MPG), as well as hotspots, which lead to pre-ignition (knock, detonation).
For the throttle body:

Similar to the intake manifold, this item accumulates sludge from the PCV system, where gases and suspended oil make their way from the valve covers into the side of the throttle body. Sludge also builds up from the intake manifold mounting point. The throttle blades will begin to stick and may not even close fully due to this, if left long enough. This causes high idling, poor throttle response, and reduced performance, and to remove the build-up is to cause the opposite.
For the gas tank:

Is our gasoline pure? No. Over time the contaminants build up in the tank, which effectively pollutes the gas that is continually added. The fuel filter does a good job of filtering this out, but without ever having the tank itself cleaned, the filter will need replaced more and more often. Besides this, some particles do pass through the filter and over time will accumulate in the fuel lines. At the end of the lines are the injectors, which also have residue building up on them due to being inside the intake manifold, where the other contaminants accumulate. So much sludge! To remove this is to increase performance by allowing better combustion due to purer fuel, which makes for increased MPG and more power.
For the engine oil:

Is our oil pure? No. Even synthetic oils will pick up contaminants, if not during production, then while in the engine. Over time parts wear down and microscopic pieces are suspended in the oil and hopefully are mostly filtered out by the oil filter. But the remaining particles sit in the oil pan, to be recirculated throughout the engine the next time the car is run. They will also tend to get lodged in small pits inside the engine, just as happens with the intake manifold. They are either transferred throughout all of the oil passages and to every part that the oil lubricates, or can lead to pre-ignition. Obviously this can wear out an engine more quickly than if they were regularly removed from the oil, as well as cause sluggish engine acceleration from sticky lifters, etc.
How to Remedy!

To clean the above as thoroughly as possibly, without actually removing the manifold, throttle body and gas tank, you'll need the following Sea Foam products:

* Sea Foam Carbon Cleaner (2)
o In a metal bottle with a screw-off cap. Used for cleaning the intake manifold, gas tank and engine oil.
* Sea Foam Deep Creep
o In a metal bottle with a spray-type nozzle top. Used for cleaning out the throttle body and the rest of the intake manifold.

Sea Foam says that they sell their products at "NAPA, Carquest, Auto Value, Parts Plus, O'Reilly and probably most independents [auto part stores]."

Follow these simple steps either 500 miles before every other oil change (every 5500-9500 miles), or 500 miles before every third oil change (every 8500-14500 miles), to keep your car running smoothly and efficiently. The first time you add Sea Foam to your engine oil, you may want to change your oil twice as soon as normal, due to the extra dirt that will be loosened up (i.e., if you normally change every 3000, do it in 1500, just for the next time).

The intake manifold and throttle body will likely need cleaning more often than the gas tank and oil, so you can do the latter less frequently if you'd like to save money.
Warning: your O2 sensors and/or spark plugs may get moderately dirtier if this is the first time you've cleaned your intake manifold and/or throttle body. You may wish to do this for the first time right before you install new ones.

1. Park car in a well-ventilated area.
2. Start car and run until it reaches closed loop (generally 5-10 minutes, and above 160?).
3. Open hood.
4. Find black hose that runs from the middle of the driver's side of the intake manifold into the black box on the firewall. This is the brake booster hose.
5. Remove the hose end from the black box; you'll hear the vacuum and the car's idle change.
* If your car stalls out, then use the middle hose that attaches to the passenger side of the throttle body. It's an L-shaped piece of hose, that connects to a black box mounted on the pass. side of the intake manifold. Pull the end connected to that box, and use that for sucking the liquid in, detailed below.
6. Place end of hose into the top of the Carbon Cleaner bottle. Allow it to suck liquid out until the engine starts to idle noticeably lower; then remove the hose from the bottle. Do not pour enough to stall the engine yet.
* Warning: Sea Foam does not recommend sticking a vacuum line into the bottle, but rather pouring the liquid into the line by using your thumb over the top of the bottle to regulate the flow. This prevents too much liquid from being drawn in and possible hydro-locking. It is your choice how to do it, at your own risk.
7. Repeat the above until between 1/3 and 1/2 of the liquid has been used.
8. Now let enough of the liquid be sucked in until it stalls the engine.
9. Turn off ignition.
10. Replace black hose end into brake master cylinder (the black box on the firewall).
* If you used the throttle body connection, reconnect it back to the black box.
11. Pour the remaining 2/3-1/2 of Carbon Cleaner into crankcase (through the oil filler tube). If you want to be exact per its instructions, you can measure out about 7.5 ounces to add to a full oil supply of 5 quarts. This turns out to be between 1/3 and 1/2 of the can.
12. Pour other full bottle of Carbon Cleaner liquid into gas tank.
13. Remove intake bellows from throttle body and push up out of the way.
14. Have someone (or something) press the gas pedal all the way down, or manually move the throttle cable assembly under the hood, until the throttle blades are fully open.
15. Spray Sea Foam Deep Creep into throttle body, fully soaking the blades, the bottom, top, and up and down into the intake manifold behind the throttle body. Use a good amount.
16. Wipe off excess liquid and visible deposits from the throttle body and blades with a shop or paper towel (especially around the edges of the blades), and reconnect intake bellows.
17. Let car sit for a total of 15 minutes from the point you stalled the engine (however much of the 15 minutes is left after you've done steps 9-16).
18. Start car (it will be harder than normal).
19. Immediately take the car for a spirited drive, being sure to rev high as well as put a load on the engine to make best use of the Sea Foam in the oil valleys and lifter and ring areas. Enjoy the fogging of your neighborhood. Then take it to the gas station and fill up the tank with 91+ octane (as always).

You are done! Congrats![/align]

smithsclassic

Thanks, for the replies. I am going to try the seafoam in the tank and cleaning throttle body (purchased some STP throttle body cleaner), change fuel filter, Change gas stations (poor gas?), disconnecting battery to reset timing (hope this works on a tahoe) after everything has been cleaned and changed. I'll let you know how it works out.