Problem: I have a '96 Z-28 for about 3 months now. Engine always worked **** from the day i bought it.

Changed: plugs, wires, distributor, cleaned injectors (ultrasounds etc), replaced fuel filter, replaced EGR valve, replaced all cooling fluid, put it on tester, checked all sensors (o2, maf etc), spanked it...

Results: Went from banging all over working in 6 cyls to working in 7 cyls to working in 8 cyls but with misfires and banging to working in 8 cyls but just not right...

Right now it seems to be almost stable, except for hickups that happen when i floor it in higher gears (1st and 2nd are too fast to feel anything). Feels like small gaps in power (they are random)... I might say they are felt even when rolling real slow in the form of shaking but i'm not sure it's same thing. I'm thinking lack of fuel but where from? I'd like to know if there may be something else wrong before i take the injectors out again and spank em. Also at idle i can hear the exhaust doesn't have a clean steady sound, fluctuates (but not like before i changed the distributor).

P.S. Car is stock no mods, I use 95 octane.

HELP PLS ...

 

Also while revving in standstill it can be noticeable that aroud 1500-2000 rpm whole car vibrates and makes a weird low sound, after 2500 engine runs pretty smooth.

 

my car is acting up pretty much like that, had the fuel pressure tested and its running at 34 psi. it should be 41-47...in goes a new fuel pump for me. get your tested. you may find an answer

 

Check your plugs and make sure there tight. Check wires & make sure they are in good shape with no breaks and are not touching anything hot or sharp.

 

x2. Something as simple as a plug wires touching the manifold can cause the sympoms you described.

 

x3. Had similar symptoms. Changed the plugs and wires, but wasn't careful enough. Started doing it again a day or so later. Crawled under the car and sure enough, a brand new MSD wire was resting right on top of my headers with a huge burn hole in it. Always triple check the routing of wires and make sure there is NO WAY it can touch the header/exhaust manifold. Changing these wires is too much of a pain to do unneccessarily.

To check it, you can park in a dark garage and look under the hood for blue sparks around the wires/exhaust manifolds. Sure sign of a burned wire.

 

I'll be looking into that today... the wires i can check, plugs i can't check tho gotta go to a service.

Can the fuel pressure be tested easily? Can any service do it?

Except plugs, wires and fuel pressure, may anything else be at fault? Valves, vaccum leaks...

 

I found the problem! Everyone with same issues note possible solution: injector electric plug safety missing... plug getting a little loose, missing signals while car is vibrating ==> misses and power loss.