What to do for (problem is identified now)

[philw349]

I'm thinking my cats have launched their innards. The car has some power and then no power, and then some power, and then no power. I'm afraid to cross the intersection with this thing sometimes. The exhaust makes a funny noise, especially when its not working right. It sounds like erratic.

In any case, rewelding in new cats will run $400 which is nearly the same price as a brand new high flo y-pipe. I've read about people here "hollowing out" their cats when this happens. Will this procedure work or is it only a temporary fix? My SHO already has other plans for my money, and this unexpected exhaust situation is not welcome at this point.

<small>[ March 14, 2004, 07:32 PM: Message edited by: philw349 ]</small>

 

[sdpatt]

First verify that one of your cat's guts has indeed turned into so many ceramic marbles. Tap gently on the cats with a knuckle or wooden broom handle and listen for the telltale rattle of loose parts. I'm not sure this is your problem though, since the exhaust system blockage will usually manifest itself as greatly reduced power at the higher exhaust flows. This coincides with the higher rpm ranges and the effect is usually proportional to the rpm. The power at low rpms should still be there to a greater level, but as the revs rise, the engine will not even be able to accelerate the car.

To remove the loose parts from the cat-back, I have remvoed the cat-back at the ******, plugged one of the exhaust tips and taped a leaf blower to the other tip. The flow backwards dislodged the blockage. Swap the flow through the other exhaust tip to ensure any parts in that pipe are cleared too.

Chances are that if a cat has failed, it will be only one rather than both that have done so. That reduces the cost of replacement by half. Erratic exhaust sounds could be from inconsistent combustion. That could be from an ignition or fuel related problem. Check for the rattle and let us know what you find.

 

[philw349]

Thanks, I got under the car and hit them with a plastic broom handle several times. Got a dull metallic noise, but no secondary noises. Also, the problem manifests itself mostly in the lower rpm range, making turns fear inducing. The higher rpms have weak but somewhat more consistent power. I guess my initial assumption was wrong. To add to the symptom list, gas mileage has been noticably poor.

If it will help I recently (and hastily before work) cleaned and re-oiled the K&N filter. I've since read that airborne oil can drip onto the MAF filament. Although the initial cleaning made a large improvement, it has been somewhat of a downward trend in power/driveability since then. A month later there is no power to speak of.

I suppose I could check the codes after I get back from school later today.

<small>[ March 10, 2004, 04:59 PM: Message edited by: philw349 ]</small>

 

[philw349]

Ok, I got the codes.

The active codes brought up 111, which I believe means systems pass.

It then did a 542 for the stored codes. This means fuel pump secondary circuit failure. Not sure what this entails.

Will a cylinder balance test be of any use?

 

[AutoSHO]

Its a good idea to run the cylinder balance test, although under no load it may not show up. Sounds like a plugs/wires problem. Have the 60ks been done? Oil in the plug wells?

<small>[ March 10, 2004, 09:54 PM: Message edited by: AutoSHO ]</small>

 

[philw349]

The previous test was KOEO. I don't know if there is a difference when it's running. I ran a KOER and got a slew of flashes but they came in so quickly I wasn't able to write them down. This was probably from not turning the wheel enough or something. After running it a second time I got the 111 (normal) code. Then I ran the cylinder balance and got a code 9, which is normal. So overall codes are normal.

I checked the plugwells, and they were completely spotless on the front bank. The rear bank I was only able to check one of them because it was hot, but it showed no signs of leakage. It was a little "moist" looking compared to the front bank, but absolutely no puddling or any visible droplets.

I'm 48k/60k on teh 60k's and it appears to be holding up. I can't wait to do it though because I 've had some valve train ticking for some time. Hoping all will be well until I do the service. Gonna start looking into cleaning the MAF filament now. Time to go do a search on that.

 

[musiccitysho]

Dont forget to reset idle after cleaning MAF
Just my 2 cents...

 

[philw349]

Alright, well. Cleaned the MAF with electrical contact cleaner. Blasted it several times. Looked clean afterward.

It is smoother running/quieter, but still gutless. It really feels like not all the cylinders are firing. I will check out the other 2 plug wells I missed. But I'm starting to run out of ideas.

Takeoff at 1000 rpms is the worst, it almost wants to stall there for a second until it builds up enough speed to move. This seems to support the idea of not enough cylinders doing the job. Who knows.

 

[billyshoe]

Bang you're muffs a good wack and you'll know if the approx. 1 in. sq. chunks of cat made it thru the pipes. I know the stock y-pipe is much better than the aftermarket Y-pipe for durability. If you have a shoshop y-pipe the chances are good that it blew one out. Other than that it could be slow for bunches of reasons including-its slow to begin with.

 

[projectSHO89]

Phil,

Try running with the MAF unplugged...

Steve

 

[philw349]

Other than that it could be slow for bunches of reasons including-its slow to begin with.

Not sure what you mean by that, but it's been a pretty strong running car for almost 5 years. I'd agree on the likelihood of the SS y-pipe going out, it was the first mod and is almost 5 years old also. I shook the mufflers, I didn't notice any real unusual noises after doing it. I still have my suspicions though.

In any case thanks for the ideas. I tried it without the MAF and it seemed a bit worse, which is good (I think). It's wierd cause sometimes it will seem like its driving through molasses, and other times it will start to catch its breath a little bit.

<small>[ March 12, 2004, 10:13 PM: Message edited by: philw349 ]</small>

 

[musiccitysho]

Clogged injector?, Is your oil thinned out and/or have a gasoline odor? A bad injector would cause a struggle and power loss under a load for sure. A telltale sign should be some blue/black smoke coming from exhaust under WOT when the power starts to break up.

<small>[ March 13, 2004, 12:34 AM: Message edited by: musiccitysho ]</small>

 

[munkee]

Can't a bad ect cause a car to run like this? shrug How is your fuel pump and filter?

 

[DavidT]

w/out chopping up your exhaust, a backpressure test is the only way to rule out any blockage. Midas will do it for around $20.
I KNOW what its like to have blockage...
At higher rpms is where the decreased power is most noticeable. RPMS don't climb as fast either.
Almost forgot, there IS one (FREE) test you can do. Disconnect the Y pipe from the catback. (Reinstall a bolt to keep the exhaust from scraping the road... but make sure the outlet at the Y pipe is completely OPEN)
The exhaust will be deafening loud, so go to a lonely backroad or ? Stomp it. If yours is like mine was, you will think someone installed nitrous when you weren't looking naughty
Hit 4000 rpms and up. With the open exhaust you will have NO low end.

<small>[ March 14, 2004, 06:51 AM: Message edited by: DavidT ]</small>

 

[philw349]

Thanks for all the great ideas. Scott and Dave's ideas helped rule out a bad exhaust. I think we stumbled onto the solution. Changed out the fuel filter and that didn't help. But I got a pressure gauge hooked up to the fuel rails and got some interesting results.

I figured it would be a little low just from hooking up the gauge. It started out at 26 psi. It took at least 6 primings of the fuel pump to get it up to 37 psi. It would go no higher. This is with the ignition key to run or whatever it is before it starts up. It took some effort to get to 37 psi, I understand it's supposed to be 40psi without much trouble.

Also, when running it hovered around 35 psi. After revving it a few times it would spike up to 36 psi, but always settled at 34 psi. I believe this is below the standard. Thought someone posted it to be 40psi primed, and 36-38 psi running. This seems to be a shortcoming. So it should be the fuel pump. I guess I didn't consider it cause I had it replaced in 2000, but I forgot it was replaced by ford. Time to get an aftermarket 190lph model.

<small>[ March 14, 2004, 07:34 PM: Message edited by: philw349 ]</small>