Hesitation problem

[spartan]

I have a 96 LT4 with on about 16,000 miles on it. I have been experiencing a problem with it hesitating when accelerating hard or just cruising at a constant speed. The problem happens no matter what gear I am in. I took it to the dealer and they changed the fuel filter and flushed the fuel injectors. The problem has seemed to get better, but it is not resolved. It only acted up once over the weekend. I was thinking it may be a fuel pump, but that that few miles, I tend to doubt it. Anyone with any similar problems, solutions, ideas, etc. Much appreciated.

 

[Vettelt193]

I have a 96 LT4 with on about 16,000 miles on it. I have been experiencing a problem with it hesitating when accelerating hard or just cruising at a constant speed. The problem happens no matter what gear I am in. I took it to the dealer and they changed the fuel filter and flushed the fuel injectors. The problem has seemed to get better, but it is not resolved. It only acted up once over the weekend. I was thinking it may be a fuel pump, but that that few miles, I tend to doubt it. Anyone with any similar problems, solutions, ideas, etc. Much appreciated.

could be the opti spark... how bad is the hesitation? it seems odd the dealer checked the fuel system before the spark. hesitation tends to come from bad spark more so than the fuel system... unless you have a single faulty injector (highly doubt that though)

 

[volavet]

Unfortunately, it may be your Opti going bad. Do you know if you water pump is weeping? If it is, it will weep into the Opti and eventually start to cause problems.

Or it may be minor, such as your EGR valve sticking, or gunk in your intake manifold. I have had all three issues with the same type of symptoms you describe. You need to see if it is throwing a code, then take it to a speciality shop who knows what their doing to find the root cause. The dealer will just replace the most expensive part without finding what is actually wrong.

My 2 cents.

 

[spartan]

hesitation problem

could be the opti spark... how bad is the hesitation? it seems odd the dealer checked the fuel system before the spark. hesitation tends to come from bad spark more so than the fuel system... unless you have a single faulty injector (highly doubt that though)

I am somewhat of a vette novice. What is the opti spark? I am guessing it has something to do with the plugs and wires?? The dealer supposedly did ran a diagnostic on it, which revealed nothing. It was my understanding that plugs and wires would have shown up on the diagnostic, but I very easily may be wrong. That is why they went the fuel filter and injector route.

The hesitation seems to be less frequent. However, when it hesitates under moderate acceleration, it will jerk you back in the seat. When it hesitates while maintaining a constant speed, it is not a severe - just feels like you missed a shift or are starting off in too high of gear.

Thanks for your help.

 

[volavet]

The Opti spark is basically your Distributor. Its a pricey piece that your wires attach to and is located behind/underneath the water pump. The jerk back in your seat scenario was the same I experienced when my Opti went bad. I hope that is not the case on yours, 16k is ridiculous miles for it to go, but you neve know with a vette. If it has that low miles, it has probably been idle for years, so your seals may be going bad and or water pump failing as I mentioned earlier. Either way, I would take it to a "corvette shop', not a dealer to find out what is actually wrong, or join a local corvette club. Members tend to be novice mechanics who may be able to help diagnose and help your problem.

 

[Vettelt193]

I am somewhat of a vette novice. What is the opti spark? I am guessing it has something to do with the plugs and wires?? The dealer supposedly did ran a diagnostic on it, which revealed nothing. It was my understanding that plugs and wires would have shown up on the diagnostic, but I very easily may be wrong. That is why they went the fuel filter and injector route.

The hesitation seems to be less frequent. However, when it hesitates under moderate acceleration, it will jerk you back in the seat. When it hesitates while maintaining a constant speed, it is not a severe - just feels like you missed a shift or are starting off in too high of gear.

Thanks for your help.

Vola's got it, and <from what I remember> has almost the same amount of miles as you do, and the same car.

I had an opti on my '93 that did similar things as yours, but it was temperature related... I am 99% sure it didn't retard or advance the timing like it should.

When it comes to your dealer, if all they can do is run a diagnostic to troubleshoot I would stop going there. I would be shocked to find out on any car that symptoms like that lead to fuel system problems. It just ins't very common and it is certainly not the place to start. The diagnostic is only as good as the computer can figure things out, and it will never figure out everything.

 

[spartan]

Thanks again for your help guys. I have a buddy that is in the local corvette club, I'll check with him to find about a local covette shop. The water pump is not "singing", so I bet you are right about the opti spark.

 

[Low drag - High speed]

Throttle position sensor. Replace it and have it calibrated on the right diagnostic computer. An ECM is just like your PC ... Garbage in/Garbage out.