KC21386

Background of mods in order:
- Headers, catback, TSP catted Y-pipe, SLP Lid
- Slowhawk tune, including delete rear o2 and front o2 codes
- Removed AIR/EGR components (still no SES codes)
- Cut out bottom of air box (still no SES codes)
- 2 years after the last mod, I recently removed the cats and put TSP ORY on. Now its throwing the following codes:

P0154 - should be o2 sensor, but those code were deleted when it was tuned
P0300 - engine misfire, I did notice this one happening when the car was hot and I left it idling in park.
P1153 - my list says something about HO2S system, but I need interpretation
P1153P - not on my code list

Soooo I have no idea what is going on with the car. All that seems like a bit much from just removing the cats, particularly because Don deleted those o2 sensor codes.

My only idea is that since I did basically 3 mods to improve airflow (!AIR/EGR, Cut the air box, and !cats) maybe it is running really lean? The car runs fine as far as I can tell, other then the occasional stumble at idle.

Please help! My inspection sticker ran out last month and all they do in MA is scan the computer.

Slowhawk

iTrader: (12)

Sounds like a bad 02 sensor or a spark problem.

DannoWS6

iTrader: (5)

Those are all pre cat o2 codes.
Its seems like the one its complaining about is the pass side.

Check for air leaks in your y-pipe.
Make sure you didn't burn your o2 wire on the pipe.
Check your grounds.

Then replace your 02's and don't get some cheap bosch ones. Get the AC Delco, but one idea is to run the rear c5 o2's up front they seem to suffer less from insufficent switching. I just order them from GM parts direct.

I deal with similar issues too but since you got a misfire code you need to check it out.

Here is some info, I'm pretty sure its not in the tune.
https://ls1tech.com/forums/pcm-diagn...153-codes.html

https://ls1tech.com/forums/attachmen...-dtc-p0134.pdf


Front o2 codes are important, they ultimately dictate your A/F ratio. The Insufficient switching garbage is a pain though. Sometimes its based on y-pipe design and the 02's not heating up quick enough. Try all the above 1st. I'm not too far away from you so if I can help in any way, I can scan and clear codes. I usually end up changing my o2's every few years.

Oh clean your maf too, especially if you run an oiled filter.

KC21386

Thank you so much for the response. I will try all of the recommendations. I bought a cheap OBII scanner that I think can reset the codes... so the plan would be to fix something, reset them, drive a bit, and see if they return? Anyone have spare O2 sensors so I can see if thats the problem without spending 200$? I know thats a long shot...

Thanks again for the helpful recommendations.

Slowhawk

iTrader: (12)

Also check the engine sensor fuse under the hood. Could be a burnt 02 wire.

NOTFAST

iTrader: (10)

You didnt get any codes removing EGR/AIR?

KC21386

Nope nothing from that mod, but I think those codes may have been removed when it was tuned. Its been a really long time, tough to remember exactly. Man was that nice to get rid of all that junk from under the hood tho, that much I remember.

KC21386

Just wanted to close the loop on this issue: I installed two new delco c5 rear o2 sensors and it fixed all the issues. Thanks everyone that helped.

DannoWS6

iTrader: (5)

Good to hear!