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Discussion Starter #1
I started it up.... and it had a hella rough idle, unique popping to the exhaust note. (it was fine last night when I parked it).. I just now went outside to check on it, and it didn't even trip?? what gives?
 

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GM has a big problem with sticking poppet nozzles on the injectors lately, :bash: they misfire when cold after sitting and the SES light will come on. If it is intermittent GM says to put injector cleaner in the fuel and change brands. (personally I don't think changing brands will help unless you are buying the real cheap crap)

Use either GM injector cleaner or "Techron" cleaner from Chevron.

If you're still under warranty let the dealer do it.
If the injector nozzles are stuck closed (not intermittent) there is a TSB outlining the procedure to ustick and clean the nozzles. Here's a partial copy of it. (It's too long to post he whole thing and diagrams won't copy)
----------------------------------------------- TSB #00-06-04-003
Rough Idle After Start, And/Or A Service Engine Soon (SES) Light (Unstick And Clean Central Sequential Fuel Injection (CSFI) Poppet Valves)
1999-2000 Cadillac Escalade

1996-2000 Chevrolet and GMC C/K, S/T, M/L, G, P Models

1996-2000 Oldsmobile Bravada

with 4.3 L, 5.0 L or 5.7 L Engine (VINs W, X, M, R -- RPOs L35, LF6, L30, L31)

This bulletin is being revised to add new information to the Correction section. Please discard Corporate Bulletin Number 87-65-07A (Section 06 -- Engine).

Condition
Some customers may comment on rough idle after start-up, especially if the vehicle has sat overnight. These symptoms may be intermittent. The Service Engine Soon (SES) light may also be illuminated. Current misfire, or history misfire codes may be detected with the Tech 2 scan tool.

Cause
A deposit build-up on the CSFI poppet valve ball and/or seat may cause the poppet ball to stick open or closed. In either case, the specific cylinder will be mis-fueled, resulting in a cylinder mis-fire condition.

Correction
A new injector unsticking and cleaning process has proven to be effective in restoring poppet valves to an "as new" condition. Injector replacement should NOT be considered as a correction for this customer concern.

The first step in this process is to make sure that the poppets are operational. The cleaning procedure will be ineffective on a poppet nozzle that is stuck closed. The J 41413 Evap Pressure/Purge Station, in conjunction with the J 44466-10 pressure regulator/hose assembly, provide the required high pressure (150 psi) source to perform the unsticking procedure. The J 39021 fuel injector tester and accessories provide the means to "energize" the injector. Some later model-year vehicles may utilize the Tech 2 to "energize" the injectors.

The second step of this process is to run the engine on a solution of 5% Top Engine Cleaner and 95% gasoline. This will effectively clean any deposits from the ball and seats of the poppets. It is very important that the engine fuel system is separated from the vehicle fuel system. Top Engine Cleaner may have detrimental effects on the fuel pump.

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Add one (1) ounce of Port Fuel Injector Cleaner, P/N 12345104 (Canada P/N 10953467), to the vehicle fuel tank for each gallon of gasoline estimated to be in the tank. Instruct the customer to add the remainder of the bottle of Port Fuel Injector Cleaner to the vehicle fuel tank at the next fill-up.
Tighten the fuel tank filler cap.
Start the engine and check for fuel leaks.
Use the Tech 2 Scan Tool to check for any stored Powertrain DTC codes. Clear codes as required.
Disconnect the Tech 2 Scan tool.
Install the engine cover.
Advise customer to change brands of fuel.


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Discussion Starter #5
I think I'm still under warranty... I whacked the bottom off my air cleaner box thingie and removed the honeycomb outta the maf, and put a flowmaster on.... that wouldn't nessessarily void warranty on that problem. would it?
 

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As long as the modifications you did haven't caused the malfunction (SES light) it doesn't void the warranty. And the dealer has to prove that your mod caused it.
 

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i did the same mods to mine and the SES light is on right now. occasionally it wont be on when i start the truck, but it almost always comes back on. for the most part it stays on. i couldnt figure out why, and this sounds like a pretty good solution because i was recommended to clean my fuel injectors b/c it was time. but i also heard that since it turns off occassionally, that it may be that the vacuum clips for the wires around the mass air meter and bonnet aren't air tight like they should and air is getting in past the MAM. so the computer is detecting a leak. i was told to spray wd-40 around the bonnet and if theres a leak the engine will cough a little. just my 2 cents. but i am gonna clean up those fuel injectors. i've got some STP crap for like 3 dollars, and it says on the bottle to use every other fuel fill-up. so does that mean that this one bottle is pretty ineffective? because jiffy lube (*******s) tried to charge me $60 to clean the injectors. thats a lot of bottles of cleaner for 3 bux a piece.
 

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Well injector cleaner is a cheap fix if it works and if doesn't work then you aren't out that much money.,

The only way to find out what's going on, or at least go in the right direction, is to get the codes out of it, there are literally thousands of possible codes on an OBD II system that will turn the light on.
 
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