I have a 95 Z28 with a current problem that is puzzling. While driving there is a slight hesitation when throttling and surging while in drive. And lately a lot of back firing too. It first I thought it was the fuel problem, and replaced the pump, but no change. Then I've changed the spark plugs without fixing the problem. I'm beginning to think the problem is with the injectors would would like advice from those who have had the same problem. 5.7 with auto transmission. Rough idle and in low gears but it seems to happen less around 50-60 RPMs. Any help, suggestions or thoughts would be appreciated.

Thanks

 

sounds like your intake is dirty or you need some more spark. i had a simalar problem when i first got my Z, replaced the spark plugs, and still nothin. then i cleaned my whole intake, tb, injectors. seemed to help alot, but i allready had ordered a MSD 6AL ignition with a MSD Blaster coil. I figured my as well, so i installed it all. i could not believe the difference just tapping the gas it threw me back, no hesitation and it pulled harder in every gear too, and best of all no backfire

 

Before spending money, I suggest a good cleaning of all connectors between the optispark, coil, and ignition module. They have a tendency to get oxydized and/or corroded and do not deliver enough primary current to the coil. If this does not help, you may want to replace the coil, and then possibly the optispark. If you have a stock engine, a stock coil is more than enough and a high performance one won't work better. If you modified the engine to where it revs over 6500 RPM, it is then a good idea to put in a high performance coil, as the spark produced by a stock type coil gets weak at high RPM. Hopefully you replaced the spark plug wires. They are a weak spot, and tend to dry out and break down and cause al types of weird prblems.

It is also a good idea to check the fuel pressure and the operation of the fuel pressure regulator. A can of fuel injection cleaner in the fuel tank may be of some help. Get a set of NOID lites & verify that all injectors are being fied. The fact that the NOIDS are lighting properly only indicates that the computer is attempting to fire the injectors, it does not mean that the injectors are working properly.

 

Well you said you changed the plugs what about the wires my 95 was doing the same and I changed the plugs and had a fuel injection service done and no help , even added the msd 6al to try and get some hotter spark to correct the problem . but come to find out I just needed to change my plug wires.