97faceoff

Hello Im new to the site so please forgive my errors. So I was reading all of the "my car stalls, stumbles, hesitates..... at certain rpm's. It seems like everyone's having issues around 2000 rpm, none of them sounded the same as mine, well here goes. 1997 Z28 LT1 automatic 179,XXX I've had the car for about 7 years and around 55,XXX of those miles, shortly after buying my car it startted hesitating at high speed around 4000-5000 rpm. I've changed the cap, roter and fuel pump the wires looked ok so I left them on, has a k&n air filter and an air foil, and still has the hesitation. First of all I know alot of you are say F@#% seven years and you still havent fixxed it, my only defence is that it not my daily driver and it only seems to do it when I really put my foot in it. Anyway I was wondering if anyone else out there have gone through this, any help would greatly appreciated thanks for reading.

Green96Z

So when you changed the cap and rotor, did you replace the opti itself? Because I would say that is the culprit.

97faceoff

Dont wanna sound stupid, but isnt the opti spark on are under the distributer cap? If so I did change it. The h20 pump went out so I thought why not change the cap and rotor to.

Injuneer

The Opti consists of two main pieces - the main body, that bolts to the block, and the cap/rotor. The main body contains the optical wheel and cam position sensor, the bearing and the harness connector. If you only changed the cap/rotor, you only changed 1/2 of the Opti.

You say "the wires looked ok"? You mean the plug wires? How did you determine by simply looking at them that they were OK? Did you run the engine in the dark and look for arcing?

Have you had the coil and the IC module tested?

Have you ever checked the spark plugs?

Have you ever scanned it for codes?

Have you checked the fuel pressure?