I have a 95 GMC that has a TBI 350.
The other night coming home running down the highway at 65 I starting getting what feels like a miss, feels like a plug wire popped off. I slow down below 60 and it stops. Driving around town at lower speeds or stopped I have no miss at all but back out on the highway when it reaches about 60mph it starts to miss or spudder. Not sure what the hell is going on.
I have no idicator lights showing up on the dash, I replaced the plugs and fuel filter and it changed nothing.
Does anyone have any idea what this could be????

 

You may need a tune up. Sounds like a faulty rotor or cap.

If that doesn't seem to be a prob you may check you TPS or CPS

 

Going to change cap, rotor, plug wires and coil today to see if that does anything. I am sure they are due to be changed since they are factory originals.

 

mine did that and i have a 1997 with a vortec 350. i changed all that and it didn't work. we then decided to pressure test, check the injectors, used cleaners, tried everything. then we decided to pull the intake off and realized the gasket was bad and we dug alittle farther down and found excess oil in the block which explains why it was missin because the plugs were getting built up. so we decided to just rebuilld it because it was already somewhat apart. and now it runs amazing. hope you don't have my problems and maybe it's just the plugs or the wires

good luck

 

My friends 95 has done the same thing for the 2 years, and no shop has ben able to fix it. I hope you find the problem, might be the same as his.

 

You might unplug and cap the vacuum hose to the EGR valve and then cap the outlet on the EGR solenoid to make sure its not a vacuum leak around it. I've seen that gasket burn out and when it opens cause a vacuum leak as well as normal EGR flow and its just too much for it. But my guess would be bad plug wires. For whatever reason they seem to like to act up the most at cruising speeds. I guess because it takes about the hottest spark at that point to light the plugs off.

 

We just to let you know where I am at now.

I changed the cap and rotor, started up and ideals good so I turn it off.
I swap out the coil for a new one and guess what, now the truck won't fire, so I swapped the old one back and still no fire.
Everything else seems to be working right, I can see fuel being pumped out the injectors when cranking but it won't bust off.
Took both coils into O'Rielly's and they seem to work.
I didnt' unhook the battery when I was swapping the coil, could this have fried something???
I took the Ingition Control module out of the distibutor so that hopefully I can get it tested today.
Any thoughts??

 

ok, heres an update.
I put in a new ICM into the distributor and I still don't have any fire.

I checked all the fuses and they are all good, it cranks good, injectors are pulsing so I know that I am getting fuel.

Any help would be appreciated.

 

Any spark at the plugs. Install an extra plug into a plug wire and lay the plug on teh manifold, crank engine, verify you have spark.

If no spark, possible pickup coil in the distributer?

peace
Hog

 

are you sure you put the rotor in?