Hey guys I'm new to this site and want to say hi. My question is on my 94z28, I assume its the opti but want some opinions. My car runs decently under half or less throttle but when you floor it it has no power and starts banging out around 4k and wont get past 4500. when you rev it while in park it starts popping between 4-6k. I'm assuming its the opti but what do you guys think?

 

i think you need to scan it and find out what codes are present

the codes for the opti will not set the ses light

 

SES light will only come on for high or low res failure on opti on a 94. However, bad cap/rotor will make it backfire out the tailpipes and not throw a code. Is this what is happening to you?

 

Check your fuel pressure and be sure you have around 40-43psi at idle.

 

Reluctance to reach the higher RPM ranges can indicate a clogged cat (you don't indicate what you've got done...how about some mods in your signature?).

 

High RPM or high load miss is usually plugs or wires. It doesn't sound like the classic "failed opti" symptoms to me. As Ryan mentioned, a bad cap or rotor is another possibility.

 

My 1994 b4c did the same thing when the cat converter plugged up i just took a air chisel and broke up the insides, started my car up and blew it all out the back, put the exhaust back together and it ran just fine and sounded better too

 

its my 94z, all stock except a blowmaster, i just got it about 2 days ago. yea it has a small miss at idle and cruises fine with a lil throttle. sometime while driving you will see the tach twitch a little. so i should start with maybe gutting the cat or removing it? and then plugs/wires/rotor/cap? another thing, at idle i can floor it and it'll light up the tires for like a second then dies on power and then bangs out. it will backfire every once in a while but very small backfire like small popping out the exhaust. it has an exhaust leak as well but goes away once it warms up. oh yea, in the morning or when it sits for a while it will start up pretty quick but once you drive it around and turn it off it cranks for a few seconds before it turns on.

 

that last part about when it warms up its hard to start is a sign of a bad opti but to me it sounds like a burnt wire and/or bad plugs. Wait till its pitch black out and look under the hood and look for arcing. Also just look at the wires for any burnt ones.

 

yea good idea, i'll try that tonight and correction i looked underneath and the cat is already gutted. so in a general sensus just try replacing the plugs and wires first? bad wires and plugs will cause it to bang out and not want to pull rpm under wot?

 

best bet is to change wires and plugs first? can bad wires or plugs cause it to run so bad at full throttle that it wont pull past a certain rpm?

 

Absolutley. I speak from experience.

 

thx man, i'm gonna try plugs and wires first and see what happens

 

its wierd also because the guy i got the car from said the 141,000k was original mileage but the oil and tranny fluid are exceptionally clean and when i pulled the driver side valve cover the head was super clean and well oilled. the engine bay is remarkbly clean too. i was wondering at some point if it was rebuilt. or maybe just clean and taken care of.

 

sounds like fuel pressure to me. rent a cheap gauge from a parts store.