96 tahoe-low rpm highway hesitation/P0308 code

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SunlitComet

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you can try depression while speeding up to just don't overheat the brakes. with brake being applied it should disable tcc control so either there is a tc problem and the brake switch is shorted making it noticeable at any speed or something is wrong elsewhere.
 
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JayG

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I didn't get a chance to check it yet but it's not occurring at all speeds. If I'm driving with the gear selector in 3, third gear, the symptom occurs around 50 mph right around 2000 rpms. If I'm in overdrive it's right around 60-70 mph again right around 2000 rpms. I keep calling it a very slight hesitation, but it's also like she's holding back a hair on and off, like she's kinda fluttering or skipping a beat here and there. And it's not when it's under any tremendous load. I can be resting on the pedal on flat ground at that rpm and it will occur. Again it's very subtle. Especially since we adjusted the cam retard correcting the misfire, but it's definitely there. Very annoying. I'll try diagnosing further regarding torque converter, brake switch, and let you know. Thanks again
 
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JayG

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Well I couldn't disconnect the brake switch. It's so buried I couldn't get to it. So I took it for a good long ride and lightly laid on the brake pedal. Although it's subtle to begin with I think it was even more subtle with the torque converter out of the equation. But I do believe the slight hesitation was still there as I laid on the brake pedal. So if that takes the trans and torque converter out of the equation, what else could it possibly be?
 
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JayG

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I have a guy I've used in the past for tranny work. I'm gonna take him for a ride just to get his thoughts on the torque converter. He's been in business for many years and will be able to tell me if it feels like a trans issue. I just wanna know for sure. And then if it checks out ok, I ll go further under the hood. Thanks again SunlitComet. I appreciate all your insight and advice. I ll report back when I know more
 

AZTahoe1998

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Is it possible to get this issue after upgrading the injectors? I am having a hesitation issue myself. Was there any luck after everything was said and done?
 

Ironman1979

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Mine did this... everyone kept telling me it was torque convertor flutter or shudder... no misfire codes eithet.. my spider assemble had been installed wrong with every other injector in the wrong hole. It would idle and drive, but felt slugish and had the fluttering feeling between 1800 and 2100 in all gears getting more pronounced with the convertor locked up. It was a 21 dollar fix and an afternoon of beer and wrenches in the driveway.
 
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JayG

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Sorry for the delay AZTahoe1998, Ironman1979, and SunlitComet. Been a little busy time for me. To summarize my issues- I never had to replace my spider assembly. After a complete tuneup of cap, rotor, plugs, wires, fuel pump, and fuel filter I was still getting the p0300 code and that annoying subtle hesitation. My mechanic friend hooked up to the scanner while driving and found the cylinders misfiring like crazy. We found that the initail cam retard was way too retarded. So we advanced it to close to +/- 0 degrees. That corrected the misfire issue, and got rid of the p0300 code. Unfortunately the hesitation was still there leaving us scratching our heads. Fuel pressure was perfect. That lead us to believe it was the torque converter. Well I got busy with other things and never had a chance to get it to the trans shop to check it out. Since then I started driving it a little more (as it really was just a sunday driver to me) and I really barely notice it to be much of an issue. If it is there it's so slight that I can't really feel it much. When we were trying to diagnose it I was really looking for it and constantly maintaining that specific RPM. Now not such a big deal. One thing I did find recently is a very slight antifreeze leak on the ground. I already replaced the notorious intake manifold gaskets probably 10 years ago. I haven't gotten under there to inspect but I'm thinking it's probably time to do them again. Which also makes me think if my little hesitation may have been the beginning stages of a vacuum leak issue. If it is I'll be sure to do the updated gaskets, updated spider assembly and pressure regulator while it's apart. So that's where I'm at for now guys. Being that the winter is upon us I may save this project for the spring. But I will chime back in with my findings and results. Thanks for the input guys and thanks to you too SunlitComet for all your advice. Much appreciated !!!
 
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