My 99 Tahoe....has been cutting out on the highway when I get up in speed.....
It will do it sometimes and won't other times...

I got home tonight and before I turned it off I noticed the idle was sputtering a bit and acting like it was going to die out..

I turned it off and then tried to restart it....It wouldn't start right of the bat until about the 3rd or 4th try..

I know this is pretty general but have no idea what this might be...
maybe coil pack, plugs....not sure.

* I replaced the fuel filter recently and that seemed to help. When I bought the truck 3 years ago I replaced the fuel pump right when I got it...

Thank for the input it's greatly appreciated,
Matt

 

was the wiring harness connector changed out with the fuel pump i think they had problems with them,was the pump good quality one they seem to eat the cheap ones

 

Not sure about the quality...got the medium priced one....wasn't oem.

I didn't replace the wiring harness either...

Thanks for the input.

 

Flipped out the fuel pump with a new wiring harness.
Still getting the misfire on cylinder 6....

I replaced the egr valve and the two bad o2 sensors I had along with plug wires...
Would love to get this issue resolved.

 

Whats the fuel pressure?was a complete tune up done or just plug wires?if you do any more ignition work use only OEM AC/DELCO,there is a possability that the poppets on the old style spider injector are going bad which can be fixed by installing the upgraded spider injector assy also check the compression on #6 to rule that out

 

Haven't ever checked the fuel pressure. Will attempt that this weekend.
I did the fuel filter, air filter, plugs, wires and think that was it.
It was only giving me the cylinder 6 misfire up until a day ago but now is giving me and EGR error code now too. Grrreat.

I did check the compression on cylinder 6 and it was around 100. it was a bit lower than the others but only by like 5 to 10 psi.

 

Fuel pressure, EGR valve or O2 sensors will not cause a single cylinder misfire. If the cap, rotor, plugs and plug wire are good. It is most likely the fuel injector on that cylinder. They were a know issue as they got up in age. They actually have been updated to a better design.

 

Here's the upgraded spider unit Rock auto and parts geek have them also