Hi my engine has been running rough at idle for a while now and getting about 12mpg. I am getting lean codes and misfire codes. I found a exhaust leak today, it looks like the gasket between the exhaust manifold and pipe is bad. Could this cause a rough running engine? Maybe it is confusing the O2's

Thank you,
Willie
2000 Discovery II
235,000 miles

 

Depending on how bad the leak is, yes, it could be causing the problems.

 

Have the same problem. Exhaust leak and rough running when cold. It smooths out when warm at which point the ticking starts. I have manifold to exhaust pipe gaskets, which will be installed tomorrow.

 

I was also getting misfire codes, which I think were related to powerwashing the engine and not the leak. I had to clear them few times and no codes anymore.

 

Did you replace these gaskets yet? I too have a leak coming from passengers side (USA) to y-pipe but canot find a sticky... I just want to know once they are off will the y pipe move enough to get the new gasket in or do I have to remove that pipe also?

 

You shouldn't have to remove the y-pipe to replace the gasket from header to the y-pipe. But be careful with the bolts/nuts. Soak overnight with PB Blaster to help loosen the rust. It's not uncommon for those to break off when removing. Once removed the Y-pipe should sag enough to allow you to place the new gasket. Also use some anti-sieze when replacing the nuts.

 

I did not install the gaskets yet, but had a very bad experience with that area on a D1. On D1 the Y-pipe needs to be taken off to change transmission filter and I broke 2 studs on each side, ended up taken the manifold out and tapping it and using new studs. I will recommend also heating it up after using penetrating spray or taken it to an exhaust shop, Which BTW I will be doing. The shop wanted the car there overnight because when warm, he said there is no exhaust leak.

 

If you got a misfire after power washing the engine and you are still running the grey plug wires, that is your problem, they are leaking.

 

Thank Mike, I do have few things waiting to be installed, including STI wires, Bosch IR plugs, pinion seal on the front diff and manifold to Y-pipe gskets. We have a new baby, which requires much more time than the disco and I am very happy dedicating that time right now to baby than disco. Right now truck is running smooth no misfire or codes, leaks are not big enough to drip and exhaust seals after 3_4 minutes of warm up, so will do everything when I get the time.

 

Well Im not always for corporal punishment but today I need a good stiff slap in the face or punch! all the horror stories of broken studs on manifold to y pipe I just put it off.. ordered all the parts ( gaskets ) and waited til the perfect day.. even though Ive been under there many many times just thinking... "if I just Do it it will be DONE"... anyway.. needless to say... today was perfect, sunny south florida, palm trees swaying in a gentle breeze just aching for a costal drive to watch the turquoise water lap against the white sandy shore... so, I got up under my disco. ALL tools and gaskets laid out and ready to go... put the 13mm socket on the 18" of new wobble extensions .... place my hand ever so gently on to the ratchet, afraid of broken stud... sweat dripping from my brow... ever so gently clicked ratchet into reverse and put socket on nut with gently pressure... apply twist.. and ever so gently the nut turned.... hmmm... YOU HAVE to BE KIDDING!I said Histerically, they ALL WERE LOOSE! HAHAHA tightened it nice and snug to proper torque.. fired up disco and SMOOOOOOTH as glass! hahahahaha SEE YA ON THE BEACH SUCKAZ!!!! just kidding.. KNOCK ON WOOD! lol anyway... all this time mine were loose! hehe my I submit my nominee for idiot of the day? lol