Hey guys I'm new to the forum and have done a lot of searching but haven't quite for exactly what I'm looking for. I just bought a 95 z28 auto, motor rebuilt about 30k ago with new plugs and wires at that time, opti is 2 yrs old, new tps, original coil (161k). It idles slightly rough and rich, it kinda chugs when you get on the gas below 2k rpms, above 2500 it starts to run great and pull hard. Crusin at 55mph it bucks real bad until i get the rpms up above 2500. I bought this as a spare summer toy and don't want to just start throwing parts at it cuz money is tight. I really want to get it right the first time. oh also the cats are hollowed but have been for 40k. Thanks and look forward to hearing back!

 

throwing any codes?best place to start is always to get it scanned or you will just throw parts at it,but sounds like opti.what kind was put in?oh,and welcome

 

^^^ agree best to have it sanned for trouble codes. the car being a 95 u may have problems finding a place with the correct scanner so do some calling around to the local parts stores to see if they can scann a 95 for codes. autozone will sometimes have the right one.

 

I actually work at a VW dealer so I have access to some stuff like a snap on mt2500 scanner. A long time gm service advisor said it's the fuel pressure regulator. When I pulled the vac there was no visible fuel but it did smell like it. I guess it's a good expanation to it stumbling at low rpm and running rich. Not sure what else would cause a rich condition as such. Thanks guys

 

well if your running rich they may cause it to seem like a miss, but its either bogging which all that extra fuel will cause it to have that rough idle, there are thousands of reasons that it would run rich, do you have anything done to the car as far as headers or cats gutted or cut out? also check your spark plugs

 

It's all stock with hollowed cats and no ses light either.

 

lets see, maf, map, 02 sensors, plugged air filter, stuck injuector are a few things that could make it run rich.

 

Lets see? Hollowed out cats? Mmmmmm, you don't by any chance have headers do you? I would opt for stock high impedence plug wires and stock plugs. A basic tune up. If you look under the hood at night you my identify some wires arching. I purchased some stock LT4 spark plug wires. Why? Well they are matched to the ignition system. Well, not excactly. Two of the wires had straight boots and the coil wire was different, but I have a set of stock slightly used wires which I swaped boots with and ofcourse used a stock coil wire for my year car! The ignition system picks up noise interference which is generated by all the power being made? Keeping it short, I would do a basic tune up and your miss will probably disappear and it's a good start to trouble shoot.

 

yeah hollowed cats may cause it to run rich if the o2's sense that car is putting out more/less than the first o2's itll tell the motor to run richer/leaner

 

my cat has been gutted for almost 2 years and runs flawlessly.and yes i have a scanner and monitor functions randomly and compare and geeat gas mileage for a v-8