I think I have an exhaust leak

[mlatten]

Well, over the last week or so I have noticed a slight, intermittent hesitation (almost feels like a miss) during slow acceleration. On top of that, I brought it up quick in first gear and she bogged heavy right around 6000 RPM - I mean it was like the rev limiter kicked in early. No CE light, I figured it was humidity.

Then, three days ago, I was showing a buddy how to pull codes on the SHO and got the O2 code for the rear bank. I bought two new Bosch's and put them in today along w/ a fuel filter. Then I reset the idle (let the battery drain for about 6 hrs.). I was happy, because I read that the car should be brought all through its performance range.

So I find a nice smooth stretch and open her up, so far not noticing any hesitation The engine hits 6000 and bogs hard, just like before. However now it sounds like my old Volvo 240DL with no muffler, only the noise is all coming from the engine bay, more specifically, the front bank of headers. I mean this thing is loud; I originally thought it was the timing belt having slipped, but the idle isn't any rougher than usual (that I can detect).

The exhaust tips are much quieter @ idle and less forceful to the palm than they normally are.

So I get her home and pull codes:

KOEO: first blinks 111 twice then spits out 211 (M) Ignition PIP signal was erratic or missing - Ignition Systems (I'll get to maint. history in a bit)

KEOR: gives me 136 (R) Oxygen sensor not switching/system lean Left or Front HO2S - Fuel control

Ok, so 35k miles ago I did a full 60k (motorcraft everything) including a cam sensor.

15k miles or so ago I did the water pump, crank sensor, and timing belt.

I did recently have out the y-pipe and swapped the front headers due to a broken stud, but I reused the header gasket that was there.

As far as the PIP code goes, I guess that could also be the DIS, which I took off of an '89 at the bone yard. Mine started right away with it in, but I'll double check all grounds anyway. (That was a many weeks ago, though)

I'm sorry for it being long-winded, but it's been a long day, and this isn't helping. If this is confusing at all, please lash out! Please ask for more info of post a hunch, as I'd really appreciate any feedback.

As always,
Matt

 

[NotSoSlowSHO]

Obviousy you have an exhast leak. Only way to fix it is to find it. It could be manifold to head, manifold to y-pipe, a broken pipe, or even a loose 02 sensor.

Find it, fix it.



First two things that come to mind as far as high RPM bogging...

Fuel delivery and Exhaust blockage

Have you checked fuel pressure at the rails?
Do the cats GLOW red?

 

[mlatten]

Alright, sounds good, thx for the reply.

The fuel pressure @ the rails BEFORE the new fuel filter was put in today was 31 psi at idle / 39 psi after 6 primes without starting it up. I was only using an analog tire pressure guage so I don't have while-driving readings. I've done tons of searching - I think I may have read over 500 posts over the last 6/7 days . . . I love this place.

I'm going to swap in another DIS tomorrow to see if she bogs, and I'll definitely break down the exhaust tomorrow after class and investigate (I'd really like to buy that $289 ShoBros y-pipe, but funds will be as tight as they can get for the next few months).

That damn PIP code scares me, though.

Cats don't glow, but I have a raspy rattle around 2800 RPM coming out of the exhaust.

Is it worth my while to invest in some sort of fuel pressure guage that I can observe while driving? Where could that come from, Autozone/Aid?

I love asking questions on here because I know I'll get all the answers every time

Thanks again,
Matt