Exhaust problem, running rich

Palli · Feb 1, 2008

After I put Flowmaster 40's catback on my 95 gt the car's been having powerloss and problems. I just recently found out that the reason was that some little chamber thingy which are supposed to be 4 of are now 2 after the catback and the car's running too rich. What can I do to fix this? Would getting headers + pro-chamber be enough or do I need to put the old chambers back? And if so, what setup would you recommend? I also hope that I made it clear enough with the chamber thingies, since I don't know what they're called in english :/

Thanks,
-Palli

d_punch · Feb 1, 2008

i don't think the catback exhaust system is the reason your running rich.

i think you mean catalytic converters????
Is thats what you changed from having 4 to 2??
but then again thats on the mid pipe, not on the catback. there's 2 mufflers on the catback.

are you getting any check engine lights on your dash?

Palli · Feb 1, 2008

Thanks for the answer d_punch! Yes catalytic converters is the name of the 'chamber thingies' - The check engine light comes on and I had it scanned for errors and the error was that it's running rich because of only 2 catalytic converters. I'll post the exact error codes when I get home (I'm at work now) - and for now I was thinking of buying an adjustable fuel pressure regulator. Note; I had the catback changed at a shop and they took two of the chambers along with the old catback and threw it away :/

Again thanks alot!
-Palli

Asylum938 · Feb 1, 2008

Changing out a midpipe wont make you run rich, are your 02 sensors plugged in? any other modifications on the car?

Palli · Feb 1, 2008

I didn't change the midpipe, just the catback and two catalytic converters were thrown away in the process. I don't know if the 02 sensors are plugged in, I'll check when I can get the car in a garage this weekend. Other mods are just suspension and a k&n filter, that's about it

Now that I'm home here are the error codes that were pulled;

P-172 hego bank 1
P-176 hego bank 2
P-181 rich limit part lean bank 1
P-189 rich limit part lean bank 2
P-556 Fuel pump relay

What do you guys reckon is wrong? Just the catalytic converters that are missing? Maybe if I install an adjustable FPR it'll start running normally again.

Thanks for the help Asylum and d_punch!
-Palli

randymcg16 · Feb 1, 2008

Unless they took a saw to your midpipe and cut the cats out and then welded replacement pipe it to span the gap I don't think they could have removed the cats. They are one piece along with the rest of the mid-pipe. If the h-pipe stayed then the cats stayed. There must be some miscommunication somewhere....

According to my code book this is what these codes mean

172- oxygen sensor indicates lean bank 1
176- oxygen sensor indicates lean bank 2
181- oxygen sensor voltage signal not switching: indicates lean at part throttle bank 1
189- oxygen sensor voltage signal not switching: indicates lean at part throttle bank 2
556- Fuel pump relay

this makes me think something is wrong with your fuel pump/fuel pump circut that is causing you to lose fuel. Maybe the boys at your shop bumped the wires or something while they were installing the catback. Might want to have a look before you go buying more stuff.

ryclef331 · Feb 2, 2008

On these cars, change the ENTIRE EXHAUST will have such a minimal impact on the car that there is NO WAY it will throw a check engine light. You exhaust is NOT the cause of your problems unless they just didn't put the o2s back in or they messed them up when they did the work on your car.

Palli · Feb 2, 2008

Thanks so much for the reply guys, at the shop they actually did saw off and weld and they told me the car had 4 catalytic converters when cars normally need just two, since I have no clue about this kind of stuff I just assumed they knew what they were talking about. I'll have a look at the wires randy and check. Gotta go to school!

-Palli

ryclef331 · Feb 2, 2008

Palli said:
Thanks so much for the reply guys, at the shop they actually did saw off and weld and they told me the car had 4 catalytic converters when cars normally need just two, since I have no clue about this kind of stuff I just assumed they knew what they were talking about. I'll have a look at the wires randy and check. Gotta go to school!

-Palli

Newer cars have o2 sensors that actually monitor the effectiveness of the catalytic converters BUT your car does NOT have this function. You can have ALL 4 of them eliminated with no negative affects on the performance of the car. Like I said before, you have another issue all together with your car.

Palli · Feb 2, 2008

Ah ok, they told me at the dealership I needed all four of them. I'm going to this mechanic friend of mine this weekend who'll check out the fuel system and find out what's wrong. But just to make clear, these error codes say I'm running lean, not rich, right? Because the dealership guys also told me it was running rich.

Thanks again ryclef
-Palli

randymcg16 · Feb 2, 2008

They would tell you that at the dealer. The fact is you can run your mustang with no cats with absolutly no problem as long as your o2 sensors are installed correctly and working (ask about two thirds of the guys on this forum). There are a few instances when a lean code is actually caused by a rich condition but that is only when the o2 sensors are bad. Since you have a fuel pump code I'm inclined to think that you are actually running lean.

PS with two of the cats gone the exhaust is going smell more like gas which may be why the dealer guys think its rich

Schiffy · Feb 2, 2008

Palli said:
Thanks so much for the reply guys, at the shop they actually did saw off and weld and they told me the car had 4 catalytic converters when cars normally need just two, since I have no clue about this kind of stuff I just assumed they knew what they were talking about. I'll have a look at the wires randy and check. Gotta go to school!

-Palli

BWAHAHAHAHAHA... Sorry, I'm not laughing at you, i'm just laughing at the fact, I'm not sure i would take and LEAVE my Mustang anywhere, where they don't tell you about hacking off a cat, and welding a pipe in it's place... I'm with Rycleff... i've got a '95 with no cats, and have no issues as far as throwing a light...

Palli · Feb 3, 2008

Heh, it's not like I left it there, I paid to get the flowmasters under. They did that and said these cars should have 2 cats instead of 4, which they said must've been a mistake from the previous owner. So I took their word for it and they took 'em off. They didn't take anything off without asking me.

-Palli

randymcg16 · Feb 4, 2008

just fyi. these cars came stock with 4 cats on them

d_punch · Feb 7, 2008

I would check the welds were there cut the old cats out, to make sure that it has sealed the mip-pipe correctly.
Also check the O2 sensor, first make sure that they are there, then check the connections and wiring. Like make sure that the harness is in all the way, and in correctly, check for any damaged wires. Any cuts or melted wires will mess things ups.
If after that all looks well, i would suggest on changing your O2 sensors, as they could be the problem once they go bad.
And if money permits you could just go with an off road mid pipe ( with no cats) as most people do, i do anyway.
Good luck

2slo95fiveoh · Feb 7, 2008

d_punch said:
I would check the welds were there cut the old cats out, to make sure that it has sealed the mip-pipe correctly.
Also check the O2 sensor, first make sure that they are there, then check the connections and wiring. Like make sure that the harness is in all the way, and in correctly, check for any damaged wires. Any cuts or melted wires will mess things ups.
If after that all looks well, i would suggest on changing your O2 sensors, as they could be the problem once they go bad.
And if money permits you could just go with an off road mid pipe ( with no cats) as most people do, i do anyway.
Good luck

X2 on that whole post.

topless95 · Feb 7, 2008

after you get everything fixed, don't be surprised if you still run rich. I have a 95 GT vert 5.0 and my exhaust travels from headders, to offroad pipe to flowmasters, and out the back. My exhaust has a rich odor, and I still get 20-22mpg every single tank.

95-stang · Feb 8, 2008

Well i put a catless x-pipe on, catback system, shorties, unplugged the export pre heaters, whipped on some afr's, all sorts of little bits and pieces, but no codes.
BUT, it does run rich on start-up, and slightly richer on the road, it does'nt seem to affect anything in a bad way though.

Palli · Feb 10, 2008

Thanks for the help everyone! The car's now at a mechanic who filled me in on things; it's been running lean, not rich like I was told at the dealership, the fuel pressure is too low and he's trying to find out what's causing it. You guys have been extremely helpful and I'll put more info in this thread when I get it.

-Palli