greg_nate

Sometimes, I get a fairly strong exhaust smell while driving - more often after the engine is hot, but not always.

I think the smell is more from the catalytic converter, but it is not quite the same "sulfurish" smell that I am used to. I have the RT cats from the Supermaxx system and perhaps they have a different smell.

Anyway, even when I bought the car new, it would occasionally have the exhaust smell. Now it is much stronger, and more frequent.

Is:
1 - Occasional exhaust smell normal, for even stock?
2 - Is it likely that I just have an exhaust leak somewhere? I got a Check engine light, that hasn't come back since I cleared it, and the message was something about primary catalyst not efficient. I am guessing that there is a leak either before or after the cat. If so, how would the smell make its way into the cabin of the car? Perhaps through the heater vents?

Thanks for any info ,and apologies in advance for what may be obvious newbie questions.

greg

Ghost Vette

Greg, I don't have that with mine. I have a 98 coupe and have also had the vert so don't think that either would make a difference.. It sounds like a leak in the system . See if you can get it on a rack while running and can see or hear a leak. Good luck...

t56gen3

Hmmm that's interesting. I remember when I had cats I literally could inhale from the tailpipe directly and not smell a thing! (Guess that's how this thing is CARB approved.) I was rather amazed. I'm wondering if you have an exhaust leak off the manifold or something prior to the cat. I could see it easily blowing out a donut gasket. You under warranty still? Any funny noises out of the exhaust?

Bill Curlee

What year car and do you have any MODS ie. HEADERS??? Is there any abnormal exhaust noise as was previously mentioned??

Bill C

greg_nate

It is an '04, and the mods are Supermaxx header system: headers, cats, xpipe, and Patriot heads.

Its hard to say about the exhaust noise, as there is a Borla Stinger, and its loud as heck.

It seemed to get worse after the tune - whether that has anything to do with it or not. And as mentioned, the check light went off, indicating the primary catalyst .

Also, it is seeming to get worse: meaning stronger smell, and more frequent.

Would I be able to test by turning off the ventilation and switching to recirculation?

greg

mbeeman350

I just purchased a 98 coupe and have noticed the same issue. No exhaust odor with the windows up....only with windows down and or the top off!!! Even with the car moving

Bill Curlee

Sounds like you might have an exhaust leak. There are a couple of places that it can escape. The first area that I would look is at any flanged area. Check to see if you have loose header bolts that attach the headers to the block. Check the AIR system hoses, check valves and flanges. Here are a few pictures of the AIR componets:





Then look under the car and chech each joint and band. You can put your hand close to each slip joint and feel if any exhaust is excaping.

Last resort, slip one of those little red airosol can straws under one of the accordian tube intake flanges and inject some spray oil into the intake when the engine is running. If you have an exhaust leak, you can bet the bank yhat you will find it!! The smoke will escape out of the area where the exhaust is leaking out.

The HVAC air intake is at the at BASE OF THE WINDSHIELD on the passengers side just below the plastic sorround under the wipers. There is no screen, guard or mesh to keep criters out!! GM,what the hell were you thinking??????????????

If you have exhaust fumes in the engine compartment, it is easy for the fumes to migrate into the HVAC inlet. Recirc will help isolate the sympyoms.

BC


Please let us know how you make out.

ptdrummer54

What was that code? Did you just hit reset to clear the light or did you reset all of the codes?

greg_nate

PT drummer:

Below are the codes. I saved them before I cleared them out.
PCM:P0420 HC - Catalyst System Low Efficiency Bank 1
TCS:C1291 H - Open Brake Lamp Sw Contacts During Deccel
TCS:C1292 H - Can't find info on this one ???
IPC : U1040 H - Loss of Communications with TCS
IPC : U1056 H - Loss of Communications with RTD
IPC : U1064 H - Loss of Communications with BCM
IPC : U1160 H - Loss of Communications with LDCM
IPC : U1176 H - Loss of Communications with RFA

Bill Curlee:
WOW! Your pics and info are so much appreciated. More than I could have expected. In fact, *ALL* of the feedback/help I have recieved from this forum has been freely given and much appreciated.

Thanks again guys. I will get a chance to look at some of the stuff this weekend, and I'll post what I find.

greg

Bill Curlee

Greg

All of the U codes indicate that you have a battery that is weak or low on charge. When the electrical system goes low on voltage the modules that have U codes mean that they shut down for a brief period.

I recommend that you have your battery charged, and checked.

That may take care of the other codes.

Bill