Header install help

Austin22

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So guys I really messed up jumping to a mod I wasn't ready for and didn't do my homework on and now need help big time due to this is my daily driver. So my question is somewhat sensor related/EGR related. So I have a 1996 Chevy C1500 5.7 Liter Vortec and the O.E spider injection with the O.E PCM at 220k+ the truck ran amazing till yesterdays install. The truck had the original exhaust manifold that runs a hose from the upper intake to the exhaust manifold I installed shorty headers that didnt come with an import for the EGR hose so I blocked it off. Also I ran the rest of the tubing of the exhaust just short of the bed of the truck and deleted the two cats. I do have the pre O2 sensors plugged in but not the post cat O2 sensors just because I'm short of tubing and money and it doesn't really make sense trying to make them work because there to read exhaust after the cats that I don't have installed, right? so not having more pipe and money I'm trying to figure out what to do now with the port on the intake and trying to fix the truck idling crazy high and now shifting hard or not shifting (limp mode?) I'm lost and the truck is almost undrivable now because the ECM is reading all types of way out stuff after the install can any one give me some ideas? All the help would be appreciated thank you.
 

red98

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So guys I really messed up jumping to a mod I wasn't ready for and didn't do my homework on and now need help big time due to this is my daily driver. So my question is somewhat sensor related/EGR related. So I have a 1996 Chevy C1500 5.7 Liter Vortec and the O.E spider injection with the O.E PCM at 220k+ the truck ran amazing till yesterdays install. The truck had the original exhaust manifold that runs a hose from the upper intake to the exhaust manifold I installed shorty headers that didnt come with an import for the EGR hose so I blocked it off. Also I ran the rest of the tubing of the exhaust just short of the bed of the truck and deleted the two cats. I do have the pre O2 sensors plugged in but not the post cat O2 sensors just because I'm short of tubing and money and it doesn't really make sense trying to make them work because there to read exhaust after the cats that I don't have installed, right? so not having more pipe and money I'm trying to figure out what to do now with the port on the intake and trying to fix the truck idling crazy high and now shifting hard or not shifting (limp mode?) I'm lost and the truck is almost undrivable now because the ECM is reading all types of way out stuff after the install can any one give me some ideas? All the help would be appreciated thank you.
Pretty sure you should have 4 cats, did you delete the rear ones or all 4?

I'm thinking you could fix most of your problems with a tune, but you have to make sure the computer knows how the engine is physically setup, you can't have the computer trying to run and EGR that you have blocked off, and you can't have the computer trying to adjust fuel trims based on inaccurate o2 sensors (because there are either no cats, not enough cats, or your sensors just aren't in right now.)

If you plug the EGR, you have to tune it out, if you delete the cats, you have to tune them out. The truck probably thinks the fuel is running incredibly rich or incredibly lean and has no idea what to do with the fueling.
 

kennythewelder

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What you are going to have to do if your not going to have the ECM reprogrammed is, add the bung for the EGR pipe on the header on the drivers side. My shortys came with that already installed. And then if you do not have to pass smog, and although its not legal to run without cats, you will need some cat simulators. I built mine from 4 spark plug spacers and added a little piece of cat material I removed when I gutted my cats and inserted it between the exhaust pipe, and 02 sensor inside of the spark plug spacer. This will turn off the 02 sensor issue.
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kennythewelder

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I have a set of Summit racing brand shorty headers. As mentioned, they had the bung for the EGR pipe. I have done a lot of modifying in my 97-5.7L. I have a Jet flash programmer but with that, you can not take out things like EGR, 02 sensors, ECT. I am at about 325 HP. I just rebuilt the rear end with 373 gears and an Eton truetrac. Then a week and 1/2 later blew up the trans. Lol then less than 3 months later I blow up the trans again. Well the trans shop made it good. Just got my truck back Monday. Anyway, point is, there is a lot of things you can do to these engines without setting off a CEL. I have a bunch or other little mods too.

I was hoping you could see the EGR pipe where it connects to the header. Guess not, but its at the collector where it meets the exhaust pipe.
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L31MaxExpress

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Pretty sure you should have 4 cats, did you delete the rear ones or all 4?

I'm thinking you could fix most of your problems with a tune, but you have to make sure the computer knows how the engine is physically setup, you can't have the computer trying to run and EGR that you have blocked off, and you can't have the computer trying to adjust fuel trims based on inaccurate o2 sensors (because there are either no cats, not enough cats, or your sensors just aren't in right now.)

If you plug the EGR, you have to tune it out, if you delete the cats, you have to tune them out. The truck probably thinks the fuel is running incredibly rich or incredibly lean and has no idea what to do with the fueling.

He can put a blockoff plate on the EGR, remove the valve and leave the connector unplugged. It will set a code but it will not try to enable the EGR and therefore the PCM will not be altering the timing and fueling as if the valve were in place and functional. Drove my Express van for nearly a year with it unplugged when the valve went bad. Only fixed it before I had to get my inspection. My valve went bad and was flopping nearly 100% open when the PCM was commanding about 20%. Was stumbling badly off-idle and no power until you had your foot really into it. Set the SES light off and it ran better. When I found out it was the EGR valve I unplugged it and ran with it. Without position feedback to the PCM the PCM disables the EGR functions.

With only front 02 sensors in place the truck should be 100% driveable. My Express van ran well with shorties, 96 LT4 cam and 1.6 rockers as well as a S10 converter for a solid 6 months before I ever tuned it.
 

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