4.0 SOHC exhaust project

[ross7070]

long time lurker, first time posting. I have a 00 explorer. I'm planning on doing some exhaust work.
the current state of my exhaust is poor to say the least but I'm planning on upgrading the following
- New dynomax 2" y-pipe (no pre-cats)... still not entirely sure how this will work out
-delete second cat
-straight pipe back to a new super 44 flowmaster
-new 02 sensors
I'm willing to replace the manifolds if needed (they still seem pretty solid)
my overall goal is to gain a little back pressure by replacing parts with large size holes (y-pipe, muffler) my truck has a bit of a rough idle to say the least, she also has no low end power
by replacing the y pipe I hope to gain a little more back pressure which will in turn allow my egr to function better; I am currently running lean (p0171, p0174) I have replaced my MAF, fuel filter, spark plugs, seafoam and anything else you could that is commonly recommended on this thread to fix this issue (I will be changing the PVC value soon.) if I'm still running lean I'm gonna go ahead and do my intake manifold and valve cover seals.
I'll post pictures and results if people are interested, if anyone had any questions, advice, or ideas I'd love to hear them!
p.s. anyone think I'll pass inspection after? (I live in NY)

 

[2000StreetRod]

no lean code elimination

I doubt that changing your exhaust will eliminate your lean codes. The PCM adjusts the air/fuel mixture (fuel trims) based on the O2 sensor results. The lean codes indicate that the PCM is unable to increase the richness without exceeding predetermined limits. Lean codes due to leaking intake manifold gaskets is common for the SOHC V6 and is probably the source of your problem.

The stock intake manifolds on the SOHC V6 flow well for a stock engine. If your heads were reworked for better airflow or you had forced induction then improving the exhaust manifolds might be worth consideration.

The PCM disables EGR (closes the EGR valve) when the engine is idling, under heavy load or at WOT. The DPFE sensor monitors the EGR flow and the PCM adjusts the flow to achieve predetermined values for driving conditions. I doubt that modifying the exhaust system will alter the EGR flow to the engine.

I doubt that you will pass inspection with lean codes. I suggest that you replace the intake gaskets before spending time on money modifying the exhaust. See Lean condition procedure

 

[ross7070]

thanks for responding and for sharing your knowledge, i was a little afraid id be alone on here.

-the reason i am redoing the exhaust in the first place is because the 02 sensors cannot get a proper read due to a quarter/half dollar sized hole about 3 inches before the up stream 02

-once the exhaust system is fixed and the 02/egr are both under proper back pressure i hope to see better performance from these systems which will inevitably result in better engine performance, and is also something that needs to be done regardless of the state of any gaskets

-i will be doing the upper/lower intake gaskets as well as the valve cover gaskets and pcv valve a few days after the exhaust and will report back. im aware the author of the thread you reference advises not to "replace components in the hopes of correcting the reported lean condition" however as this is not only a hobby/project of mine but also my daily driver therefore i enjoy the piece of mind knowing that i have replaced all components possible on my 145,000 mile explorer

-the interesting information i am hoping to provide is info about the y-pipe i plan on using as i have not found much info on it here, it can be found at http://www.summitracing.com/parts/wlk-50206
if it doesn't directly bolt on i will modify it or return it and create on myself.
if anyone has any info on this part please share

p.s.-im not rly worried about inspections, i have a friend who has a friend who knows a guy...

 

[2000StreetRod]

y pipe fit?

That y-pipe is specified for a 1993-1994 OHV V6 engine and may not fit your SOHC V6. The exhaust manifolds on the OHV and SOHC are significantly different. The distance between your exhaust manifold outlets may not be the same as the y-pipe inlet to inlet distance.

Does your existing exhaust configuration incorporate a y-pipe? My 2000 Sport stock exhaust has two downpipes each with a cat and O2 sensors before and after the cats. Then two pipes run to a single muffler with dual inlets and one outlet. The most restrictive part are the bends in the pipes just before the cats.

 

[ross7070]

GOOD NEWS!

-received the walker pipe the other day, it is solid looking, really nice welds

-my exhaust system seems different from most that i have seen pictures of on here but i cant be to certain how unorthodox it is, or if it is factory or not...(it has to be, right?)

-my exhaust does incorporate a y pipe connecting the exhaust manifolds. current y-pipe includes 2 pre-cats and an upstream 02 censor on each side. looks identical to the picture in the link posted, minus the pre-cats missing. the y-pipe's main collection happens at the first main cat.
-on the stock y-pipe it appears that the 2 pipes enter the cat separately (making the cat the point of collection) the new walker y-pipe's main point of collection is where the 2 pipes are merged via a tig-weld BEFORE the 3 bolt attatchment. i dont know if this will affect how this part fits.
-will get under the truck tm to go go about this and will post results, hopefully with pictures.

p.s. i also got new drilled and slotted front rotors, cant wait to install those bad boys and a new set of duralast gold brake pads as well, no real need for me to post ANOTHER how-to-do-your-BRAKES! post lol

 

[PJCanadaXLT]

my codes were due to a fuel pump to keeping fuelpressure.

 

[ross7070]

what type of conditions did you experience?

 

[Bronco2]

After a sohc swap into my B2 i use the OHV ypipe and cat.
I had to shorten the hight slightly and the with...
So i had three cuts and weld... Works perfect.

For your own interest i would first find the lean problem by checking gaskets upper and lower and then.. Gor forward with your exhaust..

Exhaust will not solve the problem until it is a exhaust leak...

My opinions...