8 replies to this topic

[vroom_vroom]

Hey folks. I have a 1999 Contour SE 6-cylinder (manual transmission). Here's my story.

I've had problems with the idle for a while, where it would idle very low, then rev up high, back and forth (especially when it's cold). A while back, my idle completely crapped out. I've gotten really good at managing the break and clutch with my left foot while keeping my right on the accelerator. Talent! =)

A few days ago, I was driving and suddenly heard a hissing sound. Initially, I thought I had blown a tire, but realized the sound was coming from under the hood. I took it to a shop where a tech reattached a "vacuum hose" connected to the air filter compartment. This fixed the idle issue (yay!), but not the sound or the loss of power.

So the sound only happens with acceleration and I have very little accelerating power. Sometimes the acceleration will lag or nearly fail (it's not as severe as a "bucking"). I've narrowed down the location of the hissing sound to an area toward the driver's side (not as far as the steering column) near the back of the engine compartment (cabin side), but haven't been able to find any cracked hoses (I freely admit I've only done a cursory inspection).

I'm pretty strapped for cash, so I'd love to hear suggestions before taking it back in to a mechanic. Thanks!

[BuckeyeSVT]

Sounds like a textbook clogged catalytic converter. When the converter fails the backpressure from the exhaust will not only cause the engine to have no power, but the pressure will pop the hoses off of the DPFE sensor on the rear head near the firewall (drivers side) and it will make a loud hissing or pressure escaping noise.

-Dom

[vroom_vroom]

Ooo, that's different from what I was expecting! I really appreciate your information. Even if I was able to locate the hose/vacuum leak and fix that, I'd not have known about the converter issue. Thank you!

[vroom_vroom]

I have a question for you I hope you can help me with. I took the car in to AutoZone, and got the CEL code P1506: Idle Air control overspeed error. I did not get anything for the cat. I'd hate to go through the work and expense of replacing it if I just had a hose wiggle loose. What do you think? Would I necessarily get a CEL for a clogged/failed catalytic converter? I'll be checking the DPFE as soon as it's less-than-frigid outside. =)

I really appreciate your input. I hate band-aid fixes and prefer to get right to the root of an issue, y'know?

[BuckeyeSVT]

The IAC won't cause the car to not accelerate well, nor will it cause a hissing noise under acceleration (as there is less manifold vacuum with the throttle open then closed). You won't get a code for the cat, but you might get a DPFE code if you drive it long enough. I would check the two rubber hoses that connect the EGR tube to the DPFE and make sure they are plugged in and intact. If not, your question is answered.

-Dom

[vroom_vroom]

So my DPFE sensor is hosed (not literally). Both hoses have popped off (I have yet to find them). The exhaust connection on the DPFE is melted, go figure. I can replace the DPFE fine. I'm still hesitant about the cat, since that's far more involved and expensive to replace.

If the cat is clogged, wouldn't I get a 420 code or SOMETHING? The only code I have is 1506, which could be simply from the disconnected hoses, or it could be a relatively separate IAC issue. I want to be pretty clear about what I'm dealing with, because my boyfriend is pretty gung-ho about pulling the cat off or drilling holes in the exhaust pipe to check pressure, etc., convinced that that's our problem. It makes sense, but I just want to know what the other possible causes could be for the failed DPFE. Not having a cat code definitely gives me pause.

Thanks again for your help. I'm definitely getting closer.

[Terry Haines]

...the hoses to the dpfe are not vac hoses..the dpfe checks for flow thru the egr tube.If your dpfe hoses are blowing off then it sounds like the exhaust manifold cat(s) have melted down...or maybe even the main cat,back pressure acting on the egr tube due to damaged cats causes the sensing tubes to blow off...

[Delores]

If you still doubt it is the cat... *

Is the floor board above it really hot?

Unbolt the cat and see if it suddenly drives with much more powah! (not just louder)


*the 'pipes melted at the DPFE' had me convinced...

[jeffmknight]

I had this issue when I first got my SVT, and posted the gruesome details on here way back then. The rear pre-cat had melted down and sent all its junk to the main cat under the car. All the junk clogging up the main cat caused the DPFE hoses to pop off from the resulting pressure. The hot gasses coming out of the DPFE hoses actually melted my main alternator wire, then the bare/live wire actually cut the EGR tube! It was an interesting but messy chain of events. Run a search on here for "clogged cats" to find my old posts if you want to read more and see the pics.

I would definitely agree with Dom, sounds like you've got catalytic converter failure.