PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

***HELP*** P0300 Code right before Emissions!

Thread Tools
 
Search this Thread
 
Old Feb 22, 2012 | 10:30 AM
  #1  
dementia's Avatar
Thread Starter
TECH Resident
20 Year Member
iTrader: (4)
 
Joined: Apr 2004
Posts: 878
Likes: 0
Default ***HELP*** P0300 Code right before Emissions!

Hey guys, i posted in another thread i found with a seemingly similar issue as the one I've developed recently but it was in the GenIV section and with my need to resolve this issue as quick as possible I wanted to put up another thread in this PCM Diagnostics section to cover my bases.

The car has been parked since the drive home after developing the flashing check engine light other than to drive it across the street to the parts store to read the P0300 code. I quickly checked my wires and they weren't coming into contact with anything (stock wires, too short to touch manifolds but i realize they could be giving way being 10 years old). The car doesnt seem like its falling on its face or anything while the check engine light is blinking.

I came across this thread (https://ls1tech.com/forums/generatio...g-problem.html) in a search and at first it seemed like my Cats would be the culprit as his issue was looking to be. I recently had a true dual system put on my APS twin turbo'd 02 TA (rear O2's programmed out) and had the exhaust fabbed to accept my modified stock Cats (cats had their ends chopped off and V-Band Clamps welded in so that i could easily swap them with race pipes). I'm going to try and remove the cats and run it open dumped to see if the code stops (hopefully later tonight after work) but I'm confused as to why his broken valve spring was causing the issue seeing as how the code disappeared/reappeared with the removal and application of the cats respectively. I'm hoping in my case its the cats and not a broken valve spring. I have emissions coming up next month and I need this fixed fast. Go figure this happens right before i take it in to get tested.

Anyone have any insight into what would cause the code to disappear and resurface like that with the cats going on/off?

If the removal of my cats fixes the problem what should my next step be? I obviously need the cats for emissions but I wont pass with a blinking check engine light.

If removing the cats doesnt fix the issue from what i've gathered it looks like i should check the plugs and then wires next. If it comes to it and i pull the plugs, what exactly should i be looking for? Same with the wires.

Sorry for all of the questions, just kind of in a bind as emissions are creeping up on me fast and i don't want to prolong this ordeal.
Reply




All times are GMT -5. The time now is 11:20 PM.

story-0
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-1
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-2
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-3
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-4
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-5
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-6
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-7
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-8
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE
story-9
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE