HELP ME!!! 1998 Z installed headers no cats!!!

**johnshuler08** · 07-27-2008, 01:19 PM

98 z28 with 90k, installed mac mid lengths, y pipe with no cats, 3 inch all the way back. Check eng light on, studders when accelerating, puts out a little smoke when swiches gears. I havent done anything to the pcm, someone told me that it could be running rich. What can I do without spending a fortune? Thanks in advance...

**Wesman** · 07-27-2008, 02:27 PM

Originally Posted by johnshuler08

98 z28 with 90k, installed mac mid lengths, y pipe with no cats, 3 inch all the way back. Check eng light on, studders when accelerating, puts out a little smoke when swiches gears. I havent done anything to the pcm, someone told me that it could be running rich. What can I do without spending a fortune? Thanks in advance...

Was the car fine before the header install??

Headers won't cause any of the aforementioned issues. You have one or more other problems at hand, most likely a direct result of the install of the headers.

Start with your plugs and wires, make sure you didn't crack any plugs and that they are all tight in the block. Pull the wires off and make sure there isn't any corrosion in them, and make sure they "snap" on to the plug once and onto the coil twice. Check the wires to see if any are touching the new headers.

Also check the headers and make sure you don't have any exhaust leaks where the headers meet the heads. Usually you can hear those kinds of leaks, it will sound like a Harley.

Be sure to re-check anything else you dissasembled or dissconnected to make sure things are properly hooked up. Get the code checked for free at your local Advance or Autozone, that will at least help you pinpoint the problem and give you a place to start looking.

**thearborbarber** · 07-27-2008, 04:56 PM

Also check for exhaust leaks around the header to y-pipe joints. Any leaks that let fresh air to the O2 sensors will cause an artificial lean reading.

**Spaz** · 07-27-2008, 05:16 PM

Originally Posted by johnshuler08

98 z28 with 90k, installed mac mid lengths, y pipe with no cats, 3 inch all the way back. Check eng light on, studders when accelerating, puts out a little smoke when swiches gears. I havent done anything to the pcm, someone told me that it could be running rich. What can I do without spending a fortune? Thanks in advance...

nothing done to the pcm afer a cat delete??? yes you will be running rich as hell... what color smoke??? you're going to need a tune to correct your AF ratio and to turn off your rear 02 sensors...

**Wesman** · 07-27-2008, 05:42 PM

Originally Posted by Spaz

nothing done to the pcm afer a cat delete??? yes you will be running rich as hell... what color smoke??? you're going to need a tune to correct your AF ratio and to turn off your rear 02 sensors...

The fact that its stuttering and smoking leads me to believe there is something else wrong besides being untuned.

I drove for 5 months untuned with my LT's and catless exhaust and never once did it stutter or hesitate. Might have had a couple small puffs of black smoke here or there but nothing very noticeable.

**0rion** · 07-28-2008, 12:04 AM

sounds like possibly an O2 problem. Did you have to extend your O2 harness (not sure if you do on mid length headers) and if so did you make your own extensions or buy pre-made? Check your wires to the O2's and any other wires near the headers to make sure they're not melted, easy to do. Did you keep the air and egr? Check those connections for leaks. It really sounds like an O2 issue somewhere due to the install. Have those codes read. There will be codes due to no cats but I bet you'll find an extra 1 or 2 on there.

**Spaz** · 07-28-2008, 05:45 AM

Originally Posted by Wesman

The fact that its stuttering and smoking leads me to believe there is something else wrong besides being untuned.

I drove for 5 months untuned with my LT's and catless exhaust and never once did it stutter or hesitate. Might have had a couple small puffs of black smoke here or there but nothing very noticeable.

you should have had almost power surges and bogs... it's probabbly stuttering cause of the screwed up AF ratio and the 02 sensors reading like his cats took a shit on him... the smoke would be from him running rich...

**TransAmFanatic** · 07-29-2008, 09:05 AM

i have the same problem, i got a tune, and it went away for a little while and came back...im gonna check my 02 connections, and pulgs and wires tomm. and let yall know.

**spordee1** · 07-29-2008, 01:35 PM

i am not a mechanic but i went down a similar road. i dropped a LS6 and used SLP HEADERS, cats, etc. it seems the exhaust was to cool to register properly with the O2 sensors. someone suggested CORVETTE O2s, but i ended up with a dyno that cured everything.