My car has a hesitation or slight miss,at idle and acceleration. I have to have changed knock sensor, plugs and wires and Opti, module and coil and it have still has that hesitation in do know what else to do.

 

have you had it scanned for trouble codes yet? test fuel pressure. if they havent been done in the past you may need to have injectors cleaned and flow tested.

 

The first things I think of for a hesitation is the Throttle position sensor, Map Sensor and the EGR valve. BUT your hesitation can be a symptom of the miss. I would focus on the miss, 50% of the time once the miss is gone the hesitation will go with it.

There is no way to teach someone to diagnose what is called a drivablity issue in a thread. This is a trouble shooting process that includes testing connectors and wires. Its all most all testing. I lost count of times I have had people tell me I replaced everything only to find out they either got a defective parts or installed it wrong.

It is a very good idea to get every normal maintenance item up to date but if that does not fix the problem then you should take the car to someone with the know how and equipment to track down the issue.

Example. Customer has a miss, Most likely a bad wire. They do a complete tuneup. All the normal wear items are replaced. The miss is still there, They start throwing parts at it. A new coil and new ignition module even new injectors, finally they bring it to me. I hook it to a scope. The scope shows a miss in cylinder 3, I hook a ST25 to the plug wire it fires fine. I replace the defective plug with a new one. Car is fix in less then 30 minutes. Was it a defective plug? Did the person installing the plug crack it? I don't know but the customer spent more on parts that did not need replaced then he did getting it fix. Finding the right mechanic is the key.

 

Thank you everyone for your replies. I would say this is a hard issues to resolve. I don't want to throw a bunch a money at it to fix it. I don't mind doing some heavy troubleshooting but would like to know where to start. We only drive it during the summer months. A couple of years ago I replace a leaking intake gasket and adjusted the timing on it. A few months later I replaced Cap, Rotor, Plugs, and Wires. Ran great for a year then we had the hesitation issue. So I rebuilt and clean the TBI hoping it was just gummed up or something, didn't work. Then I was thinking it could be the fuel pump but like Camaro 69 said there is no valve to test that. Hard to tell where I should start, should I look into testing the pump or should I check the timing? I appreciate everyone's input on this issue!

 

check plug wire ends and coil wire ends to make sure they are all happy. pull plugs and see if you have one that is not the same as the rest. like gas or oil on it or if it looks new. pull 02 sensors and check to see if they are fouled. have you had it scanned for trouble codes?

 

I haven't pulled any codes, but I haven't learned how to the OBD 1 system.

 

95 is an odd one, if you have an obd1 scanner check here. http://shbox.com/1/xraycable.jpg

 

I have a similar issue, I had the car tuned up, new plugs, wires, distributor cap, and after the car is all warmed up, I’ll be cruising along at 60 and put my foot into it, and it hesitates. Back off and it’s fine. From a stop acceleration is fine. It only seems to happen at about 60 and after it’s warmed up. Oh yeah, it’s a ‘94 Z28 .