Car trouble after header install!
Thread Starter
Intermediate
Joined: Jan 2008
Posts: 37
Likes: 0
From: SA TX
Car trouble after header install!
Ok so I need some help. Just installed new lG street headers in my 2K Corvette. Sounds great, put the performance is lacking- big time. It idles irregular and when I mash the pedal- it slowly picks up speed. I blocked off the pass. side air tube(till i get new part) and moved the rear o2 sensors to the front and removed the front sensors completely and blocked off the rear holes ( as instructed by Bobby @LG motorsports). It performs like it sucked in water, except when I WOT or Rev. it really high. If I had sucked in water- it would not rev. regular and would most likely die out- which it hasn't. Alright guys thats my prob. any advice would be great. Other mods are intake, plugs, OD pulley, and headers to BB exhaust. Also I was told gaskets were installed, where needed-although LG did not provide gaskets. 
Codes r P0151C; P0300H. will research these right now.
Smart@$$'s need not reply. Thx
Codes r P0151C; P0300H. will research these right now.
Smart@$$'s need not reply. Thx
Melting Slicks
Joined: Feb 2006
Posts: 2,938
Likes: 62
From: Columbia SC
First off the P0300 is a "Engine Misfire Detected" and with it being a H code should not make any difference.
The P0151 is a C code which means it is current and is "HO2S Circuit Low Voltage Bank 2 Sensor 1.
I am also running teh LG Street System and eliminated the rear 02's and moved my rear 02's to the front. Check to make sure you do not have the 02's crossed, plugged into the wrong side.
That is where I would start. After you check that clear your codes and see if problem still exist and check codes again.
Good luck.
The P0151 is a C code which means it is current and is "HO2S Circuit Low Voltage Bank 2 Sensor 1.
I am also running teh LG Street System and eliminated the rear 02's and moved my rear 02's to the front. Check to make sure you do not have the 02's crossed, plugged into the wrong side.
That is where I would start. After you check that clear your codes and see if problem still exist and check codes again.
Good luck.
Tech Contributor
Joined: Jan 2007
Posts: 19,341
Likes: 1,121
From: Dyer, IN
Check the O2 wiring for burns against the headers. As stated, make sure they are not crossed. Left to left, right to right. Also check for crack plugs for the miss......very common after a header install.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
LT headers open up a whole new can of worms for you--Often with LT's you may get very little or NO HP gains without proper tuning--
1st you need to turn off the COT system and delete all the codes related to the REAR 02 sensors--
Can you feel the eng misfiring ?? If not it may have had a one time misfire and try just clearing the code--If it comes back you have a misfire--However LT's also create "false misfires" due to the thinness of the header tubes so the knock sensors now pick up new noises that are being interpreted as misfires-- A false misfire can be tuned out by de-sensitizing the knock sensors--
And finally a complete tune with P/T street driving to correct the fuel trims back to "0" or slightly negative-- Adjusting the WOT AFR with a wideband 02---adjusting the timing
PS :make sure your front 02's are oscillating !! Bouncing very rapidly from
.100 to .950 millivolts---If they are flatlined at .450 they are junk--
A scanner or a tuning data logger can check this
1st you need to turn off the COT system and delete all the codes related to the REAR 02 sensors--
Can you feel the eng misfiring ?? If not it may have had a one time misfire and try just clearing the code--If it comes back you have a misfire--However LT's also create "false misfires" due to the thinness of the header tubes so the knock sensors now pick up new noises that are being interpreted as misfires-- A false misfire can be tuned out by de-sensitizing the knock sensors--
And finally a complete tune with P/T street driving to correct the fuel trims back to "0" or slightly negative-- Adjusting the WOT AFR with a wideband 02---adjusting the timing
PS :make sure your front 02's are oscillating !! Bouncing very rapidly from
.100 to .950 millivolts---If they are flatlined at .450 they are junk--
A scanner or a tuning data logger can check this
Tech Contributor
Joined: Jan 2007
Posts: 19,341
Likes: 1,121
From: Dyer, IN
Can you feel the eng misfiring ?? If not it may have had a one time misfire and try just clearing the code--If it comes back you have a misfire--However LT's also create "false misfires" due to the thinness of the header tubes so the knock sensors now pick up new noises that are being interpreted as misfires-- A false misfire can be tuned out by de-sensitizing the knock sensors--
Once again, your explantion has me questioning my understanding(of the last 10+ years), on how the PCM senses a misfire condition. It's been my understanding, that the PCM calculates a misfire(and position of said misfire) based on the crank velocity.....using the crankshaft sensor/camshaft sensor position.
Thread Starter
Intermediate
Joined: Jan 2008
Posts: 37
Likes: 0
From: SA TX
after xmas miracle!
Ok so I checked the plugs, cuz I couldnt get under the car. All plugs checked, good. Once under the car the front o2 sensors were crossed!
I switched them over, and Miracle! It works fine now. Keep in mind the rear o2 sensors cross over, so I assume that is y da crew did it that way. I guess I wouldnt hold it against them, even tho they cost me a small fortune to install. Anyway thanks for all the replies- and remember when installing LT's rear o2 sensors r removed and moved to the front on matching sides.
thanks, Bobby@lgmotorsports, mike@bring ur own parts, and to CF members- U know who u R
I switched them over, and Miracle! It works fine now. Keep in mind the rear o2 sensors cross over, so I assume that is y da crew did it that way. I guess I wouldnt hold it against them, even tho they cost me a small fortune to install. Anyway thanks for all the replies- and remember when installing LT's rear o2 sensors r removed and moved to the front on matching sides. thanks, Bobby@lgmotorsports, mike@bring ur own parts, and to CF members- U know who u R
