98 Z71 bogging ???

I have a 98chev Z71 that bogs after it has been started. Once you pick up speed it is fine it will not bogg at all... unless you really hammer on the gas peddle and hold it there then it will start to bog really bad all the time untill you shut down the engine and let it cool. Also toeing a load or somthing heavy in the back will caues this prblem to happen sooner. It seem like when it bogs from hard acceleration theres a point in the gas peddle where this happens.Also the engine light will come on and somtimes flash. Ive replaced the fuel filter, spark plugs, coil, water temp sensor, gas cap, cleaned air filter. Ive taken it to two garages, both ran diagnostic which said (oxygen sensor, left bank or right bank sensor ) they both checked the sensors and said they work fine but read a little lean. one of the garages was a Chevy dealer who also did a injector flush. also had them check fuel preasure at the releif valve which checks out fine even when it bogs. The truck has straight pipes off the cats and the hypertech program and air filter since day one.

This is my last resort, I'm at the end of my rope and ready to burn this truck any help would be greatly appreciated.

Have someone with a good scan tool find out what the cam retard or camshaft offset(name of it is somewhat dependant on scan tool) is. I would think they would have checked the Thottle position sensor, mass airflow sensor, and some others with the symptoms you report. If you find out that the camshaft offset is not 0 degrees, have them get it to zero.

I have a 1998 K1500 Z71 and I had problems with oxy sensors.There are several codes for oxy sensors. A P0155 or a P0141 are for heated Oxy sensor failure, then you have no activity codes (P0140,P0154,P0134,P0160), low signal codes (P0131,P0151,P0137,P0157), and high signal codes(P0132,P0152,P0138,P0158). Try this take out a oxy sensor before the catalytic conv. and screw in a back pressure gauge (must be low scale 1-30 psi ) at idle you should have 1.25 psi at 2000 rpm 3 psi. No more no less. if they are not in range catalytic conv. is bad. And remember u have two cats..

...I'm at the end of my rope and ready to burn this truck...


Don't say that... the insurance company won't pay out if they know you did it :)

Seriously tho, I think the Chevy dealer was on the right track with the injector flush, I'd say you may have a bad injector if it's TBI, possibly a few bad injectors if it's multiport. By bad, I don't mean flawed, but functioning incorrectly. There may be a common wire that has a problem with it. Check the grounds too.

The cam is right on 0, and the back preasure checks out fine. I did a quick check on TPS sensor and a few others and they seemed OK. The only thing I could not check is the MAF sensor. The mechanic at The Chev dealer was usless He pretty much told me that if his computer (diagnostic) could not tell him the problem then he couldn't help me LOL.