Chevy & GMC Vans

We were driving our van and noticed a Sulfur smell in the air. We though it was coming form surrounding area, but the van starting running really rough and the smell came back. Smell is definitely coming from the van and it is idling really rough Once you get it up to speed, it smoothes out but when you put it under a load like uphill or taking off it starts running rough again. Any ideas?

Check Fuel Pressure first.

A sulfur smell indicates a general catalytic converter problem. Poor drivability combined with a sulfur smell usually indicates a clogged catalytic converter.

Smells like bad eggs kinda, specially when you work it hard.
You need to replace the catalytic converter.

I hate being stuck behind one of these on the highway, peeyeww.
BTW, A plugged cat gets very very hot and can eventually be a bit of a fire hazzard...

I agree with bad catalytic converter. Any lights on the dash? If so get it scanned and let us know the code. A Po420 would be the code for a bad cat.

I have seen cats so hot they were literally melting and dropping hot slag on the ground.

Interesting. (not trying to hijack here). My 2000 Safari AWD is doing the same thing. 130,000 miles. New IMG, new fuel pump, new plugs, wires, cap, & rotor. Once it's really warmed up or if I'm running it hard, it'll start dying unless I have my foot in it. It will also want to die with a load on it, such as climbing a very small hill. My fuel mileage hasn't changed though. Today, it died on the way home from work and smelled hot & stinky. I had to let it sit and cool for about 15 minutes before I could get it started again. I also noticed that my exhaust tone changes just before it starts running poorly. No codes though. I thought a bad cat should throw a code. Maybe the "usual" bad cat code is really for an O2 sensor? Any ideas before I / we start cutting off good cats? I'm sure we'd both like to know. Thanks!

My advise to either of you is DO NOT THROW OUT the cat you replace.There is a indirect rebate by taking it to the scrap metal yard.On the 1994 LT that I did scrap I got for the cat I removed alone $100.00.So if you say spend $250,you get back most of that.

Thanks. Those were my thoughts too. I got one estimate to replace with factory fit downpipes to the muffler for $432.00 & they keep all of the scrap. I think it'll probably be around $100 to cut it out & replace with a non-factory pipe.

Update for PammieSue. Maybe don't take the cat off yet. Had my cat removed and guess what...still runs the same. Still stinks and sounds different once it's been driven for about 15 minutes. As long as it's above about 1500 rpm, it'll run just fine. Any lower and it will start to die and sometimes does not recover. If it does die, it takes about 15 minutes before it will start again. When it does start again, it will run well for a short time. Still no codes. I believe I just removed a perfectly good cat for nothing. I do not see any bubbles in the coolant (like for a bad head gasket). It almost acts like a bad EGR valve, O2 sensor, or MAF. Any ideas? I'm sure PammieSue (and I know I don't) doesn't want to spend a fortune to replace the wrong item. Thanks.

You can never say that two things that are similar are exactly the same..................and from what I read,you removed your cat totally.

Correct. It sounds like PammieSue if having the same symptoms and I want to recommend not throwing away money by tossing the catalytic conv. Mine is now absent from the system.

Could the fuel pump be getting hot? New fuel pump is my most recent change (last 10 days or so). I don't know if PammieSue has had any changes lately.

My point is two fold.Scanning correctly will actually give you the results of cat or O2 and in a two O2 sensor system which one.Also I would never suggest to delete the cat without a consideration of the effect that has.............

To be clear, PammieSue was complaining of a sulfur smell immediately before her symptoms begin, which is a usual indicator of a cat problem. However nowhere in my short suggestion did I recommend she delete her cat. AFAIK it is illegal to delete a cat from a system that originally had one in all 50 states. Now, whether you live in a state that does inspections might effect whether you ever get caught without a cat...

Could your fuel pump be getting hot? Its possible but not likely. Quick "fix" to check - make sure the tank is full, then go for a ride. The pump is immersed in the fuel in the tank to keep it cool, a full tank should keep it plenty cool and if the problem persists then its not the pump getting hot.