Headers & no cats cause lean condition?
Thread Starter
Racer
Joined: Jun 2002
Posts: 262
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Headers & no cats cause lean condition?
I just had Lt headers installed and deleted the cats, added heated o2 sensors, now I've got a service engine light. The code is for a lean condition. Is there a cause effect situation here. My air fuel was perfect 12.0 before. I am having it put on the dyno this afternoon and check air fuel again. Looks like I may have to give Ed wright a call.
[Modified by dscottr, 10:52 AM 2/28/2003]
[Modified by dscottr, 10:52 AM 2/28/2003]
Melting Slicks
Joined: May 1999
Posts: 2,037
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From: Sarasota FL
Re: Headers & no cats cause lean condition? (dscottr)
IF you're getting a lot more air out, then you COULD be getting a lot more air in and screwing up WOT fuel. I think a more likely explanation would be an exhaust leak.
Thread Starter
Racer
Joined: Jun 2002
Posts: 262
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Re: (scorp508)
After putting it on the dyno and changing the o2 sensors a second time, I am going to give ed wright a call. I am told that the headers and no cats are causing a timing issue with the fuel injection. It is real lean from 2,200 to 3,300 rpm.
Air fuel was 12.0 across entire curve before changes. Now 13.8 at 2,100; 18.0 at 2,500; 17.6 at 3,300, and then back to 14.s and 13.s after that. All of these numbers are under the same fuel pressure, 42 psi. We tried increasing the fuel pressure and then engine ran terrible.
Air fuel was 12.0 across entire curve before changes. Now 13.8 at 2,100; 18.0 at 2,500; 17.6 at 3,300, and then back to 14.s and 13.s after that. All of these numbers are under the same fuel pressure, 42 psi. We tried increasing the fuel pressure and then engine ran terrible.
Team Owner
Joined: Sep 2001
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
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Re: (dscottr)
This would affect a carbed car, it shouldnt affect an FI car much, i suspect an exhaust leak or a bad program.
Thread Starter
Racer
Joined: Jun 2002
Posts: 262
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Re: (vader86)
There are no exhaust leaks. It was on the lift 2 days ago. Although I haven't retorqued the headers yet, they were just put on and I've only driven about 150 miles so far.
But the car is running so bad, that I can't believe that headers and no cats could cause this much havoc. You can't drive the car in traffic at all. The engine sounds like it is totally breaking apart from 2 grand to 3,200 rpm and then it takes off like there is no problem. You can drive it around in first and second and keep the rpms over 3 grand, but as soon as you have to stop the car spits and sputters and you have to floor it to get it to go anywhere. Then when it kicks in the car takes off.
But the car is running so bad, that I can't believe that headers and no cats could cause this much havoc. You can't drive the car in traffic at all. The engine sounds like it is totally breaking apart from 2 grand to 3,200 rpm and then it takes off like there is no problem. You can drive it around in first and second and keep the rpms over 3 grand, but as soon as you have to stop the car spits and sputters and you have to floor it to get it to go anywhere. Then when it kicks in the car takes off.
Team Owner
Joined: Mar 2000
Posts: 83,381
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From: Boston, MA
Re: (dscottr)
I'm really lost for words here. If you TRULY are running 18:1 you should park that baby until you have it figured out. Thats downright dangerous if you go full throttle. You don't want to melt a piston. Its possible that you have a leak at your gaskets somewhere which are forward of the O2 sensor giving them a super lean reading and the car dumps a ton of fuel in.
<shrugs>
<shrugs>
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Race Director
Joined: May 2001
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Re: (SHiNoBi LT4)
I seeeriously doubt the exhaust could do that. Opti ?? Sounds like its ready to call it quits. :cheers:
My car behaved very much like yours did before I installed my heated O2 sensors, is there a possibility that they are not heating? I had just guessed at a fuse size for the heater circuit on mine. I eventually blew that fuse and the car went right back to running like crap. I would double check all your wiring and make sure that your heated O2's are getting the juice they need. Your drive ability issues sound EXACTLY like what mine was doing. It sputters and bogs, even sounds like crap, feels like it's running on about 4 cylinders. Eventually you just punch it, it does the same for a second and then magically takes off like a bat out of hell.
Thread Starter
Racer
Joined: Jun 2002
Posts: 262
Likes: 0
Re: (Nathan Plemons)
Thanks for the input,
I will quit taking out my frustrations by beating on the car. I've got a chip coming in the mail from fastchip. At No charge again, boy those guys are fantastic! Highly recommend, Ed Wright's outfit. I seriously doubt that the chip will fix the problem, seems way more serious than that. But, we'll see.
I will quit taking out my frustrations by beating on the car. I've got a chip coming in the mail from fastchip. At No charge again, boy those guys are fantastic! Highly recommend, Ed Wright's outfit. I seriously doubt that the chip will fix the problem, seems way more serious than that. But, we'll see.
Instructor
Joined: Sep 2002
Posts: 159
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From: Denver CO
Re: (Nathan Plemons)
No way you're gonna pin this one on the opti. If it was going out the exhaust would show rich as the unburned fuel went down the pipes.
Now, I dont' know anything about the optispark, I drive an L98. But, I wanted to help clarify this lean error code a bit. Could be an exhaust leak too.
Racer
Joined: Jun 2002
Posts: 411
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From: Palm City FL
Re: (Ken Lanham)
I drive a L98 so I don't know much about the LT1, but are you replacing the stock pipes? Does the LT1 have some sort of EGR system that is now causing an air leak of some sort. Kinda just throwing ideas here...
