Had some problems with a friends car tonite ( 97 Z28 ) that I didnt expect to have . I put on longtubes , removed the air pump and plumbing , and dissconnected the egr valve , but didnt remove it . I did use 02 simms and a block off plate on the back of manifold for the egr pipe that went to the manifold . I didnt use a LT4 knock module , but Im gonna put one those in this week .

The unexpected problem is a really bad bog up to 3K rpm's . Light throttle acceleration car will bog like alot of timing is being pulled till 3K . 3K and above car drove fine , but still would occasionally bog . After driving the car normal for awhile under light throttle the bog would go away completely under 3K , but if I came to a stoplight or something the bog would come back when I started moving again and gradually lessen as I drove the car more .

I know the OB1 stuff like the back of my hand , but this is the first OBD2 car Ive worked on . Can removing all the emmisions without programming set enuff codes where it would cause driveablity problems ? I thought to maybe , since I didnt use a LT4 KM its reading alot of false knock and pulling alot timing out ? I currently dont have a way to scan a OBD2 car .

An ideas ?

Thanks

 

I have the same setup (SLP shorties instead of Long Tubes) and I don't have any problems. I do have the knock module though. Is the SES light on?

 

Yeah , the SES light is on . I fugured it would be since I disconnected the air pump and egr .

 

You did put the "sims" in the after-cat position only? Installed the pre-cat sensors, and used decent quality extensions? Didn't contaminate the sensors? Checked the headers for leaks at the head flanges? Checked for burned wires?

Lack of (and code for) EGR and AIR shouldn't cause a bog. Neither would lack of LT4KM. Either is isn't getting spark, or it isn't getting the correct fuel.