My CEL Complex (EGR Related) Options

[XxDarkLightning]

I have been doing a lot of research on how all these components I describe work, and I feel it could be a common problem to the average car customizer. I am probably over looking a solution or my case is very specific:

I have a 98 Celica GT and last winter I put new custom cams from Delta Cams, bought the eBay header, straight piped the cat, and added a Flowmaster Hushflow muffler. I kept the diameter of the exhaust stock. Shortly after doing all these mods I started getting a CEL for EGR insufficient flow and one for EGR excessive flow and also a intermittent rough idle. As usual, I checked the functionality of the EGR valve and noticed it was sticking open so I cleaned it up, tried again, same outcome. I replaced with a new OEM one. Then my next idea was to check the VSV. Sure enough it had a small leak when I tried to create a vacuum on it and replaced that with new OEM. Now I only get EGR insufficient flow and rough idle is less often.

I started reading about the EGR and what the computer looks for to signal the insuffiecient flow and see it looks at MAP sensor (functioned fine). However I read aout needing back pressure to get the exhaust gasses back up into the intake and was wondering if that is my cause that I do not have enough back pressure which would show a vacuum still by the MAP sensor and signal computer that EGR didn't open enough even though it did.

I feel modders would have this problem frequently and was wondering what they do typically to resolve it or do you just accept it and carry on?

Thanks for reading,
Brad (Long time reader, short time poster)

[Smaay]

i have been fighting the same CEL for years, i havent checked the VSV but ill do that when i put the engine back in the car.