Lost power??

[camarokiller]

So I'm running a bassani catted x pipe and bassani catback, last week exhausted started rattling came to find out one of the cats broke from the inside so I hallowed both out. Well now it seems like I lost a ton of power. Should I just get new cats?

[LineageMach1]

Most are going to say more information is needed e.g. all your mods, power adders, has it been dyno-tuned etc.

If you gutted your cats then it would almost be the same as running offroad x pipes and if you have your o2 sensors connected and on your computer is going to send improper codes causing fluctuations as the sensors may be reading that your running rich so it'll lean out... that may be where you are feeling the loss in power.

[camarokiller]

It basically stock besides exhaust and k&n drop in. I also have the mil eliminators hooked up to my o2 sensors

[wdwrdcrzr]

Any of the pieces from the cats obstructing other parts of the exhaust?

[LineageMach1]

K my theory doesnt apply then. MIL elims would fix that.

Um.... about 3 weeks ago I posted something about my dad's car which sounded really fishy to say the least and the consensus is that a piece of his o2 sensor was sucked into the exhaust valve during start up and got lodged thus leading to engine failure. This is what the mechanic said. But I think my dad wants a new car, needless to say the car did have engine failure block cracked and oil leaked everywhere.

Hope this is not something that has happened to your car. I think the odds of that happening are 1 in 10 million heh.

[JimsZ]

You will lose torque if your cats are hollowed out. You should gain horsepower up higher, but down lower you will lose power. Its also possible you're running lean up top as well so be careful.

Do you have any codes? Did you mess up the O2 sensors or wires when pulling the pipe out to hollow cats?

And the rear O2's do not control anything outside of verifying the cats are working at correctly and sending a light if not

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[camarokiller]

I don't have any codes yet. And I blew out all the pipes to make sure nothing was clogging the pipes. But the car is not running like before feels like I'm driving a gt not a Mach

[camarokiller]

Oh and another thing when I get on it and shift around 5500 rpm it pops

[LineageMach1]

Back fire pop? That's usually a sign of running rich I have to wonder if the MIL elims are actually doing their job. I have a set of new MIL elims unopened in my tool chest, just didnt trust them lol. Decided to go with a programmer and just turn them off and get a canned tune which comes with settings for offroad pipes.

Something is sending signals to your computer that is messing things up. Do you have a programmer? SCT XCAL, Diablo predator etc?

[camarokiller]

Yes sorry was at working and didn't write out backfire pop. And no I don't have one. It was running fine before when I had the cats. I would get a code when I didn't have the mil eliminators.

[camarokiller]

Another thing notice this week that it's been wasting a lot more gas than normal

[LineageMach1]

Running rich as far as I can tell, too many signs point to the car running rich so something is up with the MIL elims or the wiring to the o2 sensors.

With the cats gutted your intake should have increased according to your MAF so it gives it more fuel and timing may be changing as well.

Driving it conservatively shouldnt notice any changes but once your WOT or above a certain RPM is when it'll start acting up.

This one is beyond me.

[camarokiller]

Yea other ppl say the same it's running rich so I'll see what I can do to fix it. Thanks

[camarokiller]

Finally check engine turned on

[JimsZ]

What code is it showing? Could be as simple as a bad O2 sensor and/or wire/connection!

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[camarokiller]

I pulled the codes and I got a p0420 p0430

[hoodley]

same thing happened to me. my bbk cats came apart. had them gutted.
wasnt much to gut...hmmm. seemed like power was down, next day rattle
rattle, what is that??? oh exhaust seems loose. adjusted....ok rattle rattle

remove mufflers, oh guess where the cat went!!!!! mufflers ruined.
replaced mufflers problem solved.

[LineageMach1]

Originally Posted by camarokiller

I pulled the codes and I got a p0420 p0430

P0420 Catalyst System Efficiency Below Threshold (Bank 1)
I'm guessing the P0430 is same thing (bank 2) Nevermind P04230 is below.

"P0430 The Engine Control Module (ECM) monitors the switching frequency ratio of heated oxygen sensors 1 (front O2 sensor) and heated oxygen sensors 2 (rear O2 sensor).

A three way catalyst converter (Manifold) with high oxygen storage capacity will indicate a low switching frequency of heated oxygen sensor 2. As oxygen storage capacity decreases, the heated oxygen sensor 2 switching frequency will increase.

When the frequency ratio of heated oxygen sensors 1 and 2 approaches a specified limit value, the three way catalyst malfunction is diagnosed.

Read more: http://engine-codes.com/P0430.html#ixzz1tCUOcivu "

So 420 tells you sensors are readind the same before and after CATs but that is normaly considering your CATs are gone. So we knew that already.

the 430 is the one that will cause timing issues etc. MIL elims are connected to your rear sensors right? The ones after the CATs and not before?

You'll need a new mid pipe with Catalytic convertors or a tune/tuner. Dont buy an OBDII reader as those are just a waste, they can clear the codes but it'll come back up after a couple hours of driving.

You'll want to fix this asap because when it comes to timing/spark etc you may end up getting detonation, your already getting back fire and wasting fuel because your ECU is getting wacky numbers.

[camarokiller]

They are hooked up to my rear o2 and today I got under the car and made sure they were plugged in right and cleared the code. Ran a little better But not completely I'll get on it tomorrow after work.

[lavasnake]

Originally Posted by camarokiller

They are hooked up to my rear o2 and today I got under the car and made sure they were plugged in right and cleared the code. Ran a little better But not completely I'll get on it tomorrow after work.

I've never used MIL eliminators. I have a predator tuner which turned off my rear O2's. I believe the front O2 sensors adjust air/fuel ratio, and the rear just check to make sure the cat's are working up to par.

Side note... did you unplug the battery for a couple minutes and allow the computer to reset itsself? That may not be the issue because the computer may automatically do that but I did it.

[LineageMach1]

Used to have to unplug the battery but our ECU doesnt have that "adaptive learning" program, think that was pre 99 Fords.

The front 02 sensors sit in fron of the cats and behind the exhaust manifolds/headers so they compare what is comming out of the exhaust valves with the second set of sensors that are located right after the cats. His codes are telling him exactly what they should "Your cats arent workin." Heh.

Turns out I dont have MIL elims in a box btw, took a look at them and they are just 02 sensor extensions. I think my MIL elims stayed on my GT when I traded it in.. oops.

[matthayn]

loss of backpressure... you lose torque

[camarokiller]

Guess I'll have to weld in some high flow cats

[LineageMach1]

Your ECU does calculations and in your case your losing power/tworque due to those calculations, not because loss of back pressure. Time and again the old back pressure adds torque or lack of back-pressure reduces torque has been debated. In older engines e.g. carb and not computer controlled engines this was an issue because there was no o2 sensor or MAF or really anything to control adjust the timing accordingly, it had to be done manualy with some good old fashioned elbow grease.

You can search this topic till your eyes are numb and you'll find answers that vary depending on who's theory it is your reading.

Your primary problem, and you two codes prove it, is that your ECU is getting bad readings. You may end up getting the same codes even with high flow cats so dont be surprised. O2 sensors make problems when it comes to messing around with exhaust set ups the same way messing with your MAF or say... taking the screen between the filter and MAF will cause problems. You basically have a mechanical problem (hollowed out cats) that has turned into an electrical problem (bad signals) which then leads to mechanical problems (bad signals=bad ECU equations=engine not running right).

If you wanna test out the back pressure theory, stick a tater in one exhaust pipe and leave the other open then see if your torque goes up, might have to duct tape the tater in though so it doesnt shoot out. (Just a joke, please dont do this ).

One example of this is, I return my ECU to stock configuration and leave my high flow exhaust system in (dont have cats) and the car runs like a v-6 and acts squirrely (and will throw up codes every single time after about 50 miles or so). Flash the ECU with a tuner that gives the performance tune parameters (tune tells the engine the o2 sensors are intake and working properly in essence tricking the ECU and viola engine runs great.

Here is a quote and the link it comes from.

"Modern vehicles are generally exempt from the effects of a decrease in back pressure. Because the computer that controls the engine will detect that the engine is burning leaner than before, and will adjust fuel injection to compensate. So, in effect, reducing back pressure really does two good things: The engine can use work otherwise spent pushing exhaust gas out the tailpipe to propel the car forward, and the engine breathes better. Of course, the computer's ability to adjust fuel injection is limited by the physical parameters of the injection system (such as injector maximum flow rate and fuel system pressure), but with exhaust back pressure reduction, these limits won't be reached.

http://mechdb.com/index.php/Exhaust_back_pressure_myth