My truck laggs and sputters when given too much throttle too quickly. starts right up and idles smooth, but if i am trying to get on the highway and have to give it some gas, it laggs/sputters but never dies. has new fuel pump fuel filter plugs wires cap and rotor, timing is correct along with firing order.
You might have some compression issues from bad piston rings or worn valves. Could have a leaky vacuum hose or intake. Throttle body or carburetor may be dirty as well. Check the Map sensor. Hope this gives you some good ideas.
SOURCE: adjust timing on 1998 GMC K2500 pick up 5.7 liter
It has to be done with a scanner. You can adjust this distributor, but there are no timing marks to watch as you move it. There is a timing mark on the balancer and on the timing cover for referencing Top Dead Center #1 cylinder only, but it is only used for dropping the distributor in to get the engine up and running. A scanner is needed to properly adjust the timing. Connect the scanner and look for a data parameter labeled ‘cam offset’ or possibly ‘cam ******.’ It will be listed in degrees. Start the engine, and bring it up to 1500 rpm. Note the reading. If the timing specification is not within plus or minus two degrees of zero, you need to move the distributor. You can move the distributor with the engine running but the timing will not change. After you move the distributor, the ignition has to be cycled off to let the computer learn the new timing spec. Restart the engine, bring it up to 1500 rpm and see what the new spec is. You must repeat this procedure until you get the timing into the specification as mentioned above. Once you have it set to spec, the code should clear.
SOURCE: no power when hit the gas
The fuel presure should be at least 60- 66 psi key on engine off, and then drop some when started, if it doesn't go any higher than 50 psi that would explain your backfire concern. If it is low then the fuel pump is weak. I have also seen soot on the little wires inside the Mass Airflow Sensor cause a concern like this.
SOURCE: 96 gmc vortec will not start
I AM LOOKING AT TIMING ISSUES OR INTAKE MANIFOLD LEAK.OR EGR VALVE STUCK OPEN.
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