Ok, I am just going crazy over my 96 LT1!
Ever since I installed headers I have had problems with low backpressure causing the EGR to act up and throw codes as well as it misfiring. I have already replaced plugs, wires, O2 sensors and gaskets twice in a few months of install and no luck. I have also replaced EGR, PCV valve and fuel filter with no luck, the car is actually stumbling more now at the 2000 RPM range than it ever had before. Since last July I have been trying to get through emissions and have had no luck. The car has 112000 miles on it and I dont know if I should just get rid of it or keep throwing thouands of dollars into nothing? There seems to be no fix! I love the car to death and that is why I still have it but now that it is getting a little worse I dont know where I should go now??? I see alot of posts about this same problem but never see a cure, I only hear about low backpressure and the EGR. So does eveyone with headers have this same issue and just deal with it? SO IF ANYONE COULD PLEASE PLEASE HELP ME I WOULD LOVE YOU FOREVER : )

HELP!

 

What are the exact codes you are getting? An EGR code caused by a low backpressure exhaust is not going to cause stumbling or misfires, as long as the valve is not leaking becasue the valve is dirty , of the place where the pintlke seats in the intake manifold isn't crudded up. Has anyone cleaned the point where EGR goes into the manifold to make sure it isn't full of carbon?

For the missing, stumbling, have you checked the IC module? Have you considered the Opti? Have you confirmed your new wires aren't burned?

 

First off thanks for the quick reply. The codes are PO400 ( exhaust gas recirculation flow fault) and PO300 ( engine misfire detected ) . It doesnt give me a PO 1, 2 or 3 showing me a certain cylinder it just says random I think. The EGR was just replaced so I hope?? they cleaned the area before they installed it. I checked wires before and didnt find any burnt but when I went to have a different place check it I went ahead and had them replaced just incase. And well the problem never went away. The new ones also have no signs of burns or arching or anything. I replaced the Ignition control module ( if that is what the IC module is ) coil wire and opti about 8 months ago. Also the problem started immediately after the header install.

I dont know if it matters but it only happens when the car is cruising along at like 1800 or 2000 RPMS ( which is how I drive to and from work everyday)I think thats all you asked hmmmmm yeah I guess? Alright again your help is appreciated.

 

O2S?

 

Never mind. I see you replaced the O2S.

 

If you love it, don't leave it.

I've got roughly 45 grand into my 97SS (bearing failure with only 8K).

I feel like getting rid of it, but it wouldn't be worth getting rid of now, so I just plan on enjoying it. Hopefully there is a lot of miles left on it now, with the new Short block and all.

Let us know the outcome.

 

By the by; I assume that when the headers were installed that the EGR tube was reconnected to the headers correctly and that the tube itself wasn't boogered?

Just a thought.

 

No when the headers were installed, the guy who has a great reputation with fbody's told me that removing the AIR would not cause me any problems with my emmissins. Well of course I found out the hard way that it does and I have been trying to fix it ever since. With the EGR I am not sure if everything is right or not?

 

Delete the egr and have your computer reprogramed.

 

Hey Robbyrob, if I get them programmed out will the EGR stop functioning and quit giving me the trouble or does it just delete it for emissions purposes?

 

The stock programming is thrown off by removing the air pump and adding the headers & stuff. Its changing the parameters that the computer is seeing. Which is not what the stock program is looking for and it trys to correct it by advancing the time and adjusting the fuel. Try disconting your battery for a few minutes and see if it clears up at all. This might straighten it out a little bit, But it will go back to the same after a while. I hope this helps you some. Let me know what happens. Right now I have a KILLER hang over and can't really think straight. Match the program to what you did to the car for optimum power. LT1 edit is a very good set up. Find someone in your aera that good with it. Becareful of who you have do it. A good program and you will find horsepower and a bad program and you'll lose H/P.

 

After my header install i got the po400 code like alot of guys do--had the code for a year, replaced egr's etc--story shorter- just messing around i put a big ugly wad of copper rtv sealant around where the header/egr tube hook-up together-a few days later, light is out--so far so good- Put the rtv all around the hook-up-Dwayne

 

Hey Dwayne, I see you got the EGR code but did you also get the 2000 rpm stumble along with it? I will get the codes programmed out but this damn hesitation is driving me nuts

Rich T

 

Nope, no hesitation that i can recall, just had the light and the po400 code when scanned, if it wasnt for the ses light i probaly wouldnt have noticed anything. When i had my baby cam installed i had the multiple cynlinder misfire code, got that corrected with a reprogram- much later on i got a bad stumble and threw a light ,then it started to flash, turn out to be an injector wasnt connected all the way- I see now you got the Mac's, you may want to check that egr/ header hook-up, might work for you also, may take a few days to find out after you put the sealant on--Dwayne

 

Depending on emissions you can have that egr business programmed out as stated.. just be careful it won't cause you to flunk emission testing. I hear a lot of states are or will soon be going to the plug in method where they just plug into your pcm and check emissions that way. I'd guess having the egr deleted from the pcm would cause you to flunk. Just be careful you don't do something you'll soon regret. I live in FL so no worries I'd say try and fix the egr before you have it programmed out - it's probably just leaking. Try using some rtv around the fittings.. I think regular rtv might not be high temp enough.. maybe the copper rtv would be best.. I dunno. Maybe someone else can chime in here

I'd guess the misfire is something else unrelated. Don't just go throwing money at the problem.. you might as well roll it up and smoke it. Don't replace the wires unless you're sure they're burnt and are arcing. You can test for arcing by parking the car in a dark spot away from any street lights, etc. and cracking the hood and peeking in. The car has to be running of course. The arcing/sparks will be very easy to see. If it's not arcing then I wouldn't worry about the wires.

Start checking your other electrical components. The most likely suspect is the optispark. Do a search for low rpm stumble or rpm stumble or something. Seems like there have been many on this board with the same problem you're describing. Likewise, there have been more than a few people on this board who have solved it.. do a search and you should find a wealth of information.

I really don't think the misfire is related to the egr system.

Anyways, that's my .02