New exhaust, now runs rich HELP!!
 

I just put on the Motoria turboback dual exhaust on my 90TII. Car ran fine before the exhaust swap. Now, the car smells heavily of rich smelling exhaust. And when you shut it off, and then restart it... It sputters real bad, and just runs like shit for about a minute and then it will run OK again. really seems like its loading up with gas.

The only thing i wasnt sure of was a tube that goes from the intake manifold, down to the catylitic converter. The new exhaust didnt have anywhere to hook this tube up, so I just plugged it off. Would this cause this rich condition? Any help would be great!! Thanks

did you remove the cat in the process? because that will make the exhaust smell heavily of gas.


BC

^Agreed. i have this exhaust on my car, same thing. pretty sure its the no cat thing, cause when i put my stock system back on for emissions, gas smell went away. you get used to it though.

It has a high flow cat on it i think. Yeah, no cat would cause a mildly ric smell, but this is really bad. And the cat wouldnt make it run like crap right after you start it...

they call it a "high flow cat", but its just a hollow pipe. i did the same thing you did in capping off the line that comes from the factory cat, but i dont remember it having any trouble. you might want to check the vaccum lines right above the turbo, i know a vacuum leak there will make it idle rough, as thats happened to me before. perhaps you knocked one loose putting the exhaust on or something.

the gas smell was so bad on mine that i thought i had leaking injectors or a busted fuel rail or something at first, but the fuel system all checked out ok.

check your oxygen sensor as well, i dont know if this will happen with yours or not, but the placement of the o2 sensor in the downpipe will cause the wire to hit a pipe on the firewall when the motor torques, bending/breaking the wire out of the top of the sensor. i replaced mine with a universal bosch, which it bent flat, but its still working.

another thing you will notice, if your just running stock fuel system without a fuel cut defencer on a stock turbo/wastegate(my car is s4 with an s5 turbo w/ upgrade turbines), the lack of flow through the wastegate will cause the turbo to overboost(boost creep) during hard pulls(i typically didnt notice it until 3rd gear). if you unplug the vacuum line that feads the boost sensor and cap it off at the manifold, your car wont hit fuel cut and will run way rich, so you dont have to worry about blowing your motor.

i realize the above is ghetto, but i didnt have the money for an fcd at the time, much less a new motor.

The top of the O2 sensor is right next to that pipe you were talking about. I havent looked yet to see if its hitting it. I already have a FCD.

I understand that without a cat, its going to have a more gassy smell to it, but that still doesnt explain why it runs soo shitty right when i start it. Sounds like its missing, and loaded up with gas... I will go out and make sure i dont have any vacuum leaks.

02 sensor is still intact, and there are no vacuum leaks. I put new plugs in and that didnt help either. any suggestions as to why this thing starts and idles crappy for a minute and then runs fine? Thanks

usually water in the combustion chamber

Don't know if it causes much on a tii, but not having backpressure with that much free flowing exhaust may cause those things.

Okay, you have an s5 which means the not enough backpressure thing is out. Your car doesn't need backpressure to close your 5th and 6th ports. That's why you have an air pump. Unless you have removed it, which is a no-no on an s5 unless you replace it with electronic crap. The rich smell is because you have a very free flowing exhaust and little to no cats. The idle could be caused by a cold start or cold temperature outside? Maybe you should clean your O2 sensor. Take some carb cleaner to it. They can get clogged and give false readings. It sounds to me like it's a cols start because you say it runs fine after it warms up a bit. The popping and such are normal. Is it idling low? If so, that could make it sound like shit, so you should try adjusting your idle. Just some helpful hints. Those are the things I would check on my 7.

exhaust leak?

i would also check to see if the TPS is out of adjustment

do you still have your air pump and your ACV hooked up?