My 2004 envoy sputters when I start it. I just changed all six spark plugs and it does the same thing. Check engine light is on. Handheld computer is logging misfires, P106, P128 codes. Lags and will not accelerate. Please help.

correction this is a 4.2L not a 2.4L
Do a 2004 GMC Envoy Slt 2.4L have a ignition module?
The engine will turn but want start no spark at the spark plugs boot what could be the cause no spark? AmanStino 3 USB ports Car charger with 1 Type port AmanStino

DIS module

Make sure plug wires go to proper coil pack or can cause problem,easy to get one on wrong pack

Get codes read by auto parts store, and most do it for little or nothing.
the code(s) will give me a better idea of what may be happening.
Spark plugs could be worn out(anything over 80k miles)
Fuel regulator, injector(s), fuel pump also could be at fault.
one more a vacuum leak.
Don't be afraid to ask questions, and there aren't any dumb questions.
Codes don't give you the part to be replaced, but give you an area to test in.

Hello erikkaloves,

The spark plugs are under the coils. To get to them you must remove the plastic cowling from the top of the engine. Then you will see the coils, there will be six coils, one for each cylinder each looks the same with an aluminum heat sink on the top. These are removed by removing and the retaining the screw and wires.

Once removed the spark plugs can be access but before you remove the spark plugs make sure the spark plug well is clear of foreign material. Dirt or debris in the spark plug well can fall into the engine and cause damage.

Regards,
netvan

A flashing light is BAD. Its damaging the cat converter. I would check or replace the spark plug wires ( if all OK, then) replace the coil pack. I would not replace anything unless they test bad. but these car are known for bad coil packs.

Engine lamp will come on if idle is too low / fuel mixture is too lean or too rich.
A faulty spark plug will cause this also.

You have 2 Problems, First problem batteries dying you have to make sure connections secure and alternator is charging your batteries (go to an Autozone or Discount advanced they will tell you). The Sputtering is either a bad SPARK PLUG or a damaged Cable going to the spark plug..Change them every 2 years.

sounds like you mixed up 2 wires...check the firing order on the block

check the spark plug wire again, yu have 1 or more crossed.