ok i got my s4 manifolds ported by my friend. he did it with the saw drill bit. its the same one in the write up. well lets just say the dam holes are huge now. did lower and upper. the lower looks like a 4 port now. what im trying to find out is. when i put them on and went to drive it down the road. all of a sudden my car would start hesitating around 4,000 to 6500 or so. one of my friends on this forum told me that the factory boost pressure sensor line has something to maybe do with it. like i have a normal autozone line on it without that restrictor that comes in the line stock. exactly what does that restrictor do?? and what could be my problem. I figure my car would be faster with these manifolds and it isnt doin junk. gimme your opinions. thanks

 

im not an n/a guy but maybe you messed up the 5/6 ports? I dunno, you might even need to reset your tps, but as far as porting the manifolds all that should have happened is you increased air flow rate, nothing that should have caused a hesitation. also how is your grounding, did you put the ground wire back on? And like i said i dunno much about n/a's but my TII has no restrictor in the boost sensor line and about 3 things tapped off of it so i dunno man, maybe someone else can shed more light on this.

-Chris

 

well can someone show me the right way to set my tps. everyone has different answers. i didnt pull off any ground with my manifolds. bumpity bump. someone has to know more. thanks for your help chris

 

bump!!

 

Unfortunately you can't port the S4 manifolds like you can the S5 manifolds. You have to see both next to each other to understand why. If you try to duplicate the S5 porting on the S4 parts then you are really going to mess up the airflow through it. The porting somewhat messes up the S5 manifolds in certain rpm spots as well but there are ways to fix them. It sounds like you are no longer using the 6 port actuators and they are removed. No big problem here. The real problem is that the end ports in the manifold sound like they are now one giant port opening. Very very very bad idea!!! What was really done when this piece was cut out is that there is now a much larger amount of turbulence through here then before you started. The air entering the engine still has to seperate into each port runner but now there is no smooth transition and there is alot of turbulence. Also due to the area increase in this spot now there is a loss in air velocity through this location. Velocity is the reason that 6 port engines make decent power regardless of their small port profiles and high turbulence. Unfortunately someone needs to do a correct writeup for each manifold style and why they do or do not work on the other manifolds. I would but I take mine to much greater extremes and some people cry about what I've done. I sincerely hope your manifold isn't ported like I think it is. If so get rid of it, install a new one from a junk yard, and don't let your friend ever touch it again. Anyone who still uses saw drill bits doesn't know how to port properly anyways. On an S4 just leave the manifolds alone. Without some good aluminum welding skills, fabrication skills, a little inginuity and patience you aren't going to improve them (S4) a noticable amount regardless of what anyone says.

 

You need that little air restriction pellet in the line. Otherwise the pressure sensor will be seeing waaaaay to much air. I had problems with my car when I did a vacuum line job and found out about the little restrictor. I put one in and away went the problems Though it wasnt the same problem you are having. I was having hesitation above 7k rpms and my check engine light would come on.

 

On Turbos the restrictor is there to stop pressure spikes hitting the sensor and causing fuel cut. But NA's don't have fuel cut so that's not your problem.

 

hmm well thanks rotarygod. so i guess i should slap these fresh stock lower and upper manifolds back on. the guy that did it for me is a v8 guy. he didnt want to use that saw bit anyway. he did cause i told him to.lol o one more thing should i change just the bottom and keep the top. since i didnt really cut anything up top just made it bigger

 

I'd like to see some pics of what was done if you can post them. From your description it sounds pretty bad but there is always the possibility of miscommunication. I'd just stay on the safe side and put it all back to stock with that style manifold. I can show you how to improve flow the the middle one if you like without hurting flow or drivability in any way.