New Headers - Exhaust Details
Thread Starter
Intermediate
Joined: Jun 2003
Posts: 35
Likes: 0
From: Tulsa OK
New Headers - Exhaust Details
I have a 93 LT1 and I just bought headers (exotic muscle) for my car. I'm getting ready to put them on but realize now I need to get some questions answered. The first one being, I planned on removing the air pump and the piping for it to clean up the look of the engine. I have O2 sensors taps for the headers and planned on putting them to use. Will removing the air pump cause a computer error code? Will removing the air pump cause the 02 reading to be "bad"? Any recommendations? Also, does anyone make a replace pipe to bypass the stock cats when you have headers? Can I get a chip to bypass a air pump and/or fool the O2 sensors?
Thanks for any advice...!
Thanks for any advice...!
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: New Headers - Exhaust Details (Dark_Rider)
If you use heated O2 sensors you will be OK without the AIR pump system as it helps to preheat them during warmup. I don't think the '93 LT1 had any feed back on the AIR system (for sure the late L98s didn't) so you will not get any codes thrown by the ECM.
It's not a good idea to try and fool the ECM about O2 sensor readings; they are what gives your Vette good part throttle performance and great fuel economy.
You could have a pair of Random Tech. bullet cats installed in a front Y. Try to find a good exhaust shop to do the job.
It's not a good idea to try and fool the ECM about O2 sensor readings; they are what gives your Vette good part throttle performance and great fuel economy.
You could have a pair of Random Tech. bullet cats installed in a front Y. Try to find a good exhaust shop to do the job.
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Re: New Headers - Exhaust Details (65Z01)
The airpump is electric on the 93 LT1 and believe me, if it is not plugged in, it sits the check engine light off. exotic muscle makes pipes to connect back to the stock exhaust which I have. To be honest I dont like them. They would probably work fine with a 6 speed but they hit on the automatic transmission. For the $195.00 you pay for them you would be much better off to take it to an exhaust shop and have them to make connctors. But do get the band clamps to connect to the headers with.
Thread Starter
Intermediate
Joined: Jun 2003
Posts: 35
Likes: 0
From: Tulsa OK
Re: New Headers - Exhaust Details (93 ragtop)
What I wonder about is the error code coming from the air pump being unplugged or is it because the O2 sensors see there is a lot less air in the exhaust??? If the computer is doing a check to see if the air pump is attached, I could put a small coil or maybe a resistor in its place to simulate the air pumps impediance (resistance). But if the air mixture is unnacceptable to the O2 sensors when you pull out the air pump, how the heck can you get rid of the thing and not sacrifice your performance?
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Re: New Headers - Exhaust Details (Dark_Rider)
As stated the AIR pump on the LT1 is electric and there is a diagnostic for it. It's an easy checkbox in the computer to turn off, but you will likely get a code if you don't progoram it out of the computer. Same goes for EGR unless you program the computer to never try and use it.
BTW, the AIR pump is only there it pump air down the exhaust to help the cats light off faster. During this time the car is in open loop and not reading off of the O2 sensors anyway. By the time the car is warm enough to hit closed loop the cat should be functioning and the AIR pump should be off, otherwise like you say it could screw up your O2 sensor readings.
The short answer to your question is that yes, you will need a chip to avoid setting a code but your engine will run just fine without the AIR pump in place.
[Modified by Nathan Plemons, 8:52 AM 5/1/2004]
BTW, the AIR pump is only there it pump air down the exhaust to help the cats light off faster. During this time the car is in open loop and not reading off of the O2 sensors anyway. By the time the car is warm enough to hit closed loop the cat should be functioning and the AIR pump should be off, otherwise like you say it could screw up your O2 sensor readings.
The short answer to your question is that yes, you will need a chip to avoid setting a code but your engine will run just fine without the AIR pump in place.
[Modified by Nathan Plemons, 8:52 AM 5/1/2004]
Pro
Joined: Jan 2004
Posts: 626
Likes: 2
From: Nashville
Re: New Headers - Exhaust Details (Nathan Plemons)
GM has a service buletin out on how to disable. It was from an Impala SS. I did it. I haven't turned it off in the computer yet. I will get a code now and then. I just scan it and clear. I also removed the EGR and blocked it off. I haven't gotten a code yet from that but someday I probally will. I'm saving now for LT1 edit. I have heard of the pump running when it isn't supposed to which would make you run rich. :cheers:
Advanced
Joined: Dec 2002
Posts: 73
Likes: 0
From: St. Augustine Florida
Re: New Headers - Exhaust Details (Dark_Rider)
Take a look at Casper Electronics on the web. Their site has a link for 02 simulators, and some good information about what the computer takes from the sensors before and after the cats. Hope this helps you out.
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Re: New Headers - Exhaust Details (Mikes92)
I ran with my air pump unplugged for some time and never got a check engine light. I wanted to make sure before I eliminated it completely.
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Re: New Headers - Exhaust Details (Nathan Plemons)
If the ECM throws an AIR code then it has direct feedback; if it throws another code due to AIR pump malfunction then it is using indirect data.
If there is direct feedback the ECM can be fooled by looping back the command line to the feedback line. For example, this can be done with the EGR system where a sensor is used to see when the EGR is open. Here you simply loop the command signal back to the sensor input.
To do this with the AIR system you need to know some details about the electronics involved. For sure the ECM pulls the AIR relay low to activate it; if someone knows about the AIR sensor, a "work around" would be easy to rig without reprogramming the EPROM.
If there is direct feedback the ECM can be fooled by looping back the command line to the feedback line. For example, this can be done with the EGR system where a sensor is used to see when the EGR is open. Here you simply loop the command signal back to the sensor input.
To do this with the AIR system you need to know some details about the electronics involved. For sure the ECM pulls the AIR relay low to activate it; if someone knows about the AIR sensor, a "work around" would be easy to rig without reprogramming the EPROM.