Hi guys, well the 7 is back up and running with a swapped motor. The previous motor has a terrible porting job and dumped at least a dozen quarts of oil thruogh the exauhst. Today i had to get the stock cat. replaced in order to pass emissions testing, and it passed. With that said, could the 2 other smaller cats in front of that one be clogged and causing the power loss or does it sound like a 5&6 port problem? It seems to me like the 5&6 ports might be working beacause lets say i floor it in 2nd at 3K i can feel the power increse at about 4K, then it pulls fairly strong untill 6500, then at 7k it toatally stops accelerating. It is very strange, with it flored it won't go above 7k when in 2nd gear or higher, it also starts running very shitty and i has hear backfiring ect. also when i let of the gas it backfires like crazy... too much fuel maybe?... could the front 2 cats. be clogged?
Thanks, Philip

Oh and BTW, its an S5 N/A

 

make sure you vdi is wired and working. My car is the same. Just seems like you vdi isn't kicking in.

 

I have an S5 n/a as well and have the same problem. It isn't the cats because I have none.

I would look into the 5ht/6th ports and VDI. I have a strong feeling that is the problem on mine I just havn't had the time to fix it the way I want it fixed.

 

if the 5th&6th ports are working... what else could it be?

 

yea mine si doing that **** now!!! =/ when i baught my car it was doing that after a while my care was normal cuz i could feel it. but it came back now. so i know its not my 5th and 6th ports its my vdi. do i take it out and clean or just check it??

 

FIXED IT!!! i don't know if this will help any of ya'l but there was that one little vaccume line that i forgot to connect when insalling my motor The vaccume line of the front of the secondary fuel rail was dissconnected, of check that line if any of you are having this porblem, if it is plugged in, follow it to the back of the engine where it goes into the vaccume web.
BTW: does anyone know what this line does? something to be with the secondary injectors i would assume....

 

 

Yes! that yellow vaccume line is the one i was refering to, now could anyone tell us what it is for, how it workes or what it does?
Thanks!

 

im goign to take a stab. Raises your fuel pressure based on engine vacuum/rpm
basically your engine wasn't getting enough fuel to get past 6.5k. Ill have to check that but im pretty sure my vdi isn't working.

 

yea i dont have a vac line on that. and when i tried to look where it goes on the back, i couldnt find a web or ne thing. imma go have to buy a hose for that and find where it goes.

 

ok i just checked, it does not go to the back, it tursns to the driver side ane plugs in to the metel line that is located just behind the meatal elbow at the back of the water pump under the fill neck. So if you can find where that small coolant line comes into that elbow on the water pump, just go to the back of the car by about on inch or too and that's where it pligs in. It is just under the front of the UIM. anyway those directions are confusing but let me know if u still can't find it and i'll post a pic.

 

lol i tried to look for ot but didnt find it my engine is so clutered up. can u post a pic please? thanx alot

 

replace the plugs, that's fixed hesitation for me before