3.8l Exhaust Questions - TCCoA Forums
 
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post #1 of 8 (permalink) Old 08-06-2013, 10:59 PM Thread Starter
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3.8l Exhaust Questions

I'm hoping someone here can help me out with a question / solution / etc.

I am about 75% sure that at least my drivers side cat is clogged.

- Vacuum test - sits around 16-18 at idle, dives immediate to 0 when hitting the accelerator, and comes back up pretty quickly when letting off the exhaust.

- gas mileage is horrid - and I mean horrid - It was better than it was, but, still not great - I'm guessing the latest tank is about 12mpg or so. I do get an occasional rich code on the drivers side O2, and a pretty regular fuel pump code 542 - but - I'm thinking that may be the CCRM)

- All fuel injectors are new (two weeks old now) - spark plugs / wires / rotor / cap are 6 months old.

I have a v6 3.8l, and wouldn't mind getting a bit of boost and a nicer exhaust tone. What are my best options to go (and at a reasonable cost) - I also don't want it to sound like a ricer. I was looking at the Magnaflow setup as a bolt-on.

I'm hoping someone "more knowledgeable than me" can chime in and maybe get some pointers. Maybe I have some sort of a vacuum leak somewhere that I can't seem to find. I have done the propane test (nothing found) and the intake (upper and lower) gaskets are new, head gaskets are 24,000 miles old along with the cylinder heads (1998 style NEW heads - work done by Ford)

I am assuming the head gaskets are good - no coolant loss, no oil in coolant or coolant in oil.

As a short term solution - I could "delete" the cats and have pipes clamped or welded in (clamping would be easier for me!) and then replace down the road before my next emissions test in 12/2014 (car is a 95 so I get the sniffer test)

I did pass emissions in February with the car - not as great as its done in the past (2004 or so is one paper I found)

Car overall has 125,000 miles on it now.
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post #2 of 8 (permalink) Old 08-06-2013, 11:39 PM
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Try pulling the O2 sensors and with the bungs open, see what kind of vacuum you get at idle.

The front O2s, anyway.

If it improves, that means you've got an obstruction in the exhaust. So, using antiseize, you put the front ones back in, and pull the back ones.

If it stays improved, it's not the cats, but downstream. If, however, it turns to second-hand hay (what you get after you run it through the cow or horse ..), then you've got plugged cats.

Do be aware you CAN get the Y pipe with the cats from places like RockAuto if you're not in California - and last I looked, AZ <> CA *grins*

RwP
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post #3 of 8 (permalink) Old 08-06-2013, 11:57 PM Thread Starter
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It's a 95 3.8 - so no rear o2 sensors. I may do the drill test to see - even if I can get it with better mileage I can do a full exhaust in a couple of months.
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post #4 of 8 (permalink) Old 08-07-2013, 01:07 AM Thread Starter
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Also, if anyone has the Magnaflow 23351 - any opinions - and pipe sizes if you know them?
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post #5 of 8 (permalink) Old 08-07-2013, 11:12 AM
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have you checked you fuel pressure?? that may explain some of it if the regulator is stuck shut.

I can explain it to you, but I can't understand it for you

Tim

1994 Cougar 3.8L Supercharged
1990 Tbird Supercoupe
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post #6 of 8 (permalink) Old 08-07-2013, 07:44 PM Thread Starter
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Stopped at Autozone and did a "parking lot borrow" of the fuel pressure tester - pressure tests out at 35psi idle, rises with acceleration.
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post #7 of 8 (permalink) Old 08-28-2013, 11:11 PM
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does the car have a gas smell sometimes? bad fuel milage can be a bad vapor canister or lines that run to it (dry rot) i had this issue on my 94, (missfiring and CEL lights) fixed the lines going into the canister and it ran fine. this is part of the car's vacuum. check out this thread

http://forums.tccoa.com/showthread.php?t=43557

on my old 3.8 that i sold, i simply removed the stock pipe, replaced it with a "DUAL" 4.6 pipe and cut the mufflers off, car sounded beastly.

mercury cougar
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post #8 of 8 (permalink) Old 08-28-2013, 11:45 PM Thread Starter
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It occasionally smells "rich" I did replaces the lines around the vapor canister itself - they were "rotten" but, I haven't found any additional worn or damaged lines.

I also just did a bit more digging - found one more that looked rough (under the AC hose area against the body) but didn't appear to be cracked all of the way through.

Are there more around the fuel tank area I should look at? I never "smell gas" when the gar is sitting. Took a look at the vacuum hose from MN12Tech - will check a few more tommorow - wouldn't surprise me if the ones around the fuel tank are gone also.

Last edited by fkostyun; 08-29-2013 at 12:16 AM.
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