would a exhaust leak cause a bad idle?

[empie1]

i noticed that my exhaust is leaking between the the down pipe flange and the 02 housing (i think i need to tighten the nuts)...i have a horrible idle right now, could this be causing it?

 

[crunchymilk]

possible. depends if the leak is turbo/02 housing or 02housing/downpipe

I had a leak at turbo/02 housing and its caused a bad idle because air was getting out before it reached the 02 sensor. Made all sorts of problems, however, it was a HUGE leak, you could stick your finger inbetween them (that's what happens when all of the bolts except wiggle loose)

I'm not quite sure how it got messed up, because i know some people even run an open 02 housing, but as soon as I bolted the new gasket and tightened it back down the car went 100% back to normal.

 

[olmytsi]

He said between the turbo and downpipe so it's post 02 sensor. Answer is no.

 

[crunchymilk]

but he also said at the turbo, not the 02 housing, so it's a possibility.

 

[olmytsi]

Most people consider the 02 part of the turbo but yes it's a possibility.

 

[elementalwindx]

On my 90 RS Turbo which is 100% stock, I swapped out the 14b for a small 16g w/ a 2.5" o2 housing, and I tried to slot the stock downpipe flange to fit onto it and of course that did not work right and caused a hefty leak between the o2 housing and the dp, and that made a 300rpm difference, so instead of idling around 1k-700 rpm I was around 500-600 rpm. I swear it makes a difference because it did this exactly til I got a 2.5" down pipe welded to my 2.25" stock exhaust system.