New LS1 Owners - Newbie Tech - dead miss after mods

Hi, i just finished up doing some mods. PnP TB, pacesetters, slp lid, tick master, new plugs, 3 inch duals with borla xr1s. Now under a load i get a sporatic miss. Could this be the computer 'learning', or do i need a tune?

CEL's?

How long after the mods did the miss start occurring? I'm assuming you have an SES light on if you put headers on? Have you read the codes to see if it's showing anything other than o2 sensors? What rpm range does this miss occur at?

Check the plugs. You need a tune, but it shouldn't be missing that bad.

No idea what CeLs are. I can only notice the miss in 5th or 6th gear, pulling around 2-3 grand

I assume Check Engine Light...took me a little bit myself since I've always seen it as SES.

No idea what CeLs are. I can only notice the miss in 5th or 6th gear, pulling around 2-3 grand

Check Engine Lights = CEL's. If its that slight, I have to say its due to the upgrades. Check your plugs.

plugs or o2 sensors

Mine does the same thing and wasnt the plugs or wires, i just changed them. Car shows no CEL.

I didn't buy the O2 extensions. I spliced them myself. I could have gotten a bad splice on one of the wires I guess. its almost as though its loading up, cause it pulls like a champ in lower gears at higher rpms.

i dont think the rear o2s could affect it could it? (to that degree)
I do have the extensions on mine if this helps at all.

My rear O2s are disconnected. The front I spliced

2-3 grand only in 5th or 6th? Or 2-3 grand in any gear? Is it just one miss and then it goes away or does it constantly miss through that rpm range?

You probably have a bad 02 splice. Do it right and get the longer 02s

The front O2s will set of an SeL even functioning correctly without cats correct? Wondering if i can check them without redoing everything.

You probably have a bad 02 splice. Do it right and get the longer 02s

^^^ +1... If you have never changed them before your probably due for new ones by now... Get the corvette O2s they are longer. No need for extensions.

I've seen a lot of people that splice the O2's have problems. How you splice them can alter the voltage, even a little bit will cause problems.

^^^ +1... If you have never changed them before your probably due for new ones by now... Get the corvette O2s they are longer. No need for extensions.

Only difference is extensions are $30 new O2's are $150.

Only difference is extensions are $30 new O2's are $150.

^^^ ya I know that. But since he splice the O2. (If that is the problem) he will need new O2s.... if he buys the Fbody O2s he will need extensions. If he just buys the Corvette O2s he will not need the extensions. Should have been more clear about what I was tryna say

^^^ ya I know that. But since he splice the O2. (If that is the problem) he will need new O2s.... if he buys the Fbody O2s he will need extensions. If he just buys the Corvette O2s he will not need the extensions. Should have been more clear about what I was tryna say

Good point :bang: :jest:

sounds like an ignition issue with the plugs. but very well could be the spliced o2

Now that its dark out, i did the 'lightning' under the hood check. No apparent plug arcing. I guess ill be replacing O2s =( /wavebye mailorder tune

You will be throwing rear o2 codes if you don't have cats you shouldn't be having front o2 codes. If you are then you more than likely have a bad splice. Check your codes first

Also make sure your MAF is clean and your intake bellows are all seated correctly too. I had a dead miss on my car before doing mods it happened right around 2300 rpms it felt like the car fell flat on its face at that rpm and then picked up right where it left off at. I was getting o2 codes thrown also. I unplugged my MAF and ran the car like that for a day and noticed it wasn't doing it. Changed out my MAF sensor and that fixed it. I would clean your MAF and throttle body, make sure all your intake bellows and air filter is installed right and read your SES codes.

Tremendous ideas thanks

Ok, i got to advance auto and they read my codes. I had one for EGR (which i removed), Skip shift (also removed), MAF, ( not sure on that one). And Bank 1 o2 sensor. Car runs pretty rough, and if i gained any power from all the mods, i cant tell it.

Try cleaning your MAF sensor, if that doesn't help, unplug the MAF and run the car witt it unplugged for a day and see if that fixes it.

Your bank 1 is your front o2 sensors so there's a possibility that you did splice that one wrong as well. Try the thing with your MAF first before going out and spending more money on o2 sensors.

I cleaned the maf, and i also tried driving with it disconnected, and there was no change. I also did another splice on one of my old O2 sensors and replace the drivers o2 with it, also, no change.

It would probably help if you had a scanner more available because you could clear and re read the new codes to see if that o2 sensor is still throwing codes. If it is then I would probably say that's the root of the problem

I added some MSD superconductors, and a cheap summit a/f narrowband. The engine still shudders pretty bad under a load. The a/f guage is showing pretty dang lean all of the time. I only get 1 green bar under full throttle, the rest of the time it is 2 yellow 2 red, or less.

Could the lean condition be causing my misfiring? If so, Whats the best way to remedy it? tune? Fuel pump?

Thanks for your help

FYI I had similar issues, no SES lights but terrible misfire and black rear bumper.

Had a plug wire that was bad.