Question for the Auto Mechanics, Rotten Egg Smell *REVISITED* Pg 5

Catalytic converter is almost ALWAYS the "symptom".

Of improper fuel mixture.

Bingo

could be the battery. I know when batteries go bad or leak they smell like rotten eggs.

You're not getting error codes? No check engine lights???

Then it's your cat.

I would say it's a bad vagina rod. Or probably worn out menstrual brushes. You probably have summer air in your radical tyres, too. I'd check the carbonator coil for combustion. Or your old lady has a yeast infraction & she leaked some fluid on your venarial seats.

Damn, here I was thinking it was the canuter valve.

LOL Might as well throw those in there with all of the uninformed wild assed guesses that have been shot out so far.

Hell, it could also be the tire pressure or lug nuts. Maybe even the dome light or the horn.

I swear, half the people that responded did not even comprehend the post. They felt they just needed to respond before even understanding the question. Withholding actual car specs did not seem to even help.

Last Edited by BrokenTech on 01/05/2017 12:21 AM

It's because everyone thinks that they know something about cars, and they feel that they are smarter than the people who work on cars. While that may be true of the monkeys down at the local tire store chain, parts store chain, or department store "service department", it's a little bit more complicated and involved than just throwing out wild guesses for something you once heard someone say.

I also like "Oh, the codes tell you what's wrong now". Uh huh. Yeah, OK...

AC73684047 is the only one that I saw who was on the right track.

You don't have enough information to accurately make that call yet. It's nothing more than a guess.

Here's the rub though - If it does indeed end up being the correct guess (after it was determined using proper diagnosis procedures by someone who actually knows what they're doing), you'd act all smug like you knew what you were talking about. You do not. Any good technician has seen that scenario play out more than once...

clogged cat homie!

clogged cat can be caused by faulty bank 1 o2 sensor giving false reading causing the computer to think its running lean and dumping extra fuel. or it could be caused by either a faulty thermostat or coolant temperature sensor, which would cause the computer to do the same thing. or if its a car that utilizes a secondary air pump for emissions, a faulty solenoid would cause the vehicle to run rich, causing cat to become clogged. clogged cat can easily be checked by using a infrared temp gun to measure the temps at the front and rear of cat. if the temps are close to the same its not clogged, but if the engine side is significantly higher....bingo!

but rotten egg smell generally points to a clogged cat.
you will also notice a decrease in power, especially under load or going up steep hills. vehicle will seem to "bog" down

Problem-rotten egg smell
rotten egg smell generally points to clogged cat
Clogged cat generally caused by a rich fuel mixture condition
running rich generally caused a failure in any of sensors related to the fuel/emissions

bank 1 & 2 o2 sensors
map or maf sensor
IAT or coolant temp sensor
secondary air system
egr system

a sticking open secondary air solenoid or egr valve can cause a engine to run rich without throwing a DTC by allowing unmetered air into the exhaust system, causing bank 1 to detect a lean fuel mixture and adding fuel to compensate resulting in a unnecessary rich fuel mixture condition.

Last Edited by The Wild 0nes on 01/05/2017 01:25 AM

There you go!




Or a rich condition. In the early stages anyway...

i edited my post with a mini root cause analysis for dummies lol

Hey man, thanks!

If OP plays his cards right and gets his fuel mix corrected, he might not have to replace the cat yet.

Start with the O2 sensors, you might even have the skill to replace those yourself, if you nail down which bank it is!

Your to rich in fuel, 30 plus years with VW. Your car would never pass SMOG in Kalifornia BI YEARLY SMOG inspection. With your modified engine the only fuel you should use is Standard Oil high grade like a BMW.

You know most aren't going to do the required testing though. They're going to do the easy way. That usually goes something like one of their friends saying, "my buddy had the same exact problem and it was XXXXXX ", so that's what they replace.

Still, you gave him what he asked for though, right?

You can lead a horse to water...

This ^^^^

The regulator is over-charging the battery.

could be a capacitor going bad

sadly, thats how most mechanics fix cars now a days.
Replace until its fixed.

fuck that.

na, blinker fluid is burning causing the smell. it needs changed. headlight rings must be going bad. time for a rebuild.

I know. Sadly, I think there were a few in this thread...

The car is an 01 Grand Prix GTP modded.

Its not clogged, but thats not to say it will not get that way. It has plenty of power, it still turns the wheels over at 40 mph if I put the pedal down just like it did when I originally installed the mods.

It does not always have the smell. I tend to baby it around town. As was mentioned in an earlier post about running it harder seems to help, if I get on the highway for 40 miles or so it stops for a few weeks. Changing where I get gas also makes it stop for awhile. Running it harder does indeed seem to make it go away, for awhile. When I am out tomorrow I will run the dog shit out of it and see what happens.

According to the computer, everything is still functioning fine, no fault codes. My real time OBDII software(torque pro) shows the temp as 180 degrees as it should be with a 180 degree thermostat. Short of actually doing manual checks with voltmeters and such, I am assuming the computer would alert me if something was running out of spec.

Running rich I suppose could be a possibility here if unmetered air is getting in, I will check into it.

Last Edited by BrokenTech on 01/05/2017 01:59 AM

Sulphur in the gasoline.

I am more than capable of doing the work, I always do. I am not a pro, but I know my way around a car. This time its just throwing me for a loop. I just refuse to start throwing unnecessary parts at it hoping it fixes it. And I am trying to get to the bottom of it before I do have to replace the cat.

At this point in time, I am of the opinion its me and the car does not like how I am driving it and wants to be driven harder. Or, there is unmetered air getting in.

Last Edited by BrokenTech on 01/05/2017 02:04 AM

heater core / heat diffuser leaking, passenger side under the dash

if bank 1 is detecting a false lean condition due to unmetered air, you'll see a big fluctuation in the reading on bank1o2 in freeze frame diagnostics. and was your pcm tune a mail order or real time tune?

*** you can also do a basic check if you have a good dtc reader. if your fuel trim is running greater than 10%, the computer is trying to compensate for something. one thing to remember here is that your car is supercharged. its better to run lean with boost than rich, so be careful running it hard until you get it straightened out. running rich with a boosted car opens up the opportunity for detonation...which is something you want to avoid like the plague.

Last Edited by The Wild 0nes on 01/05/2017 02:06 AM

Either you're not paying attention or you don't understand.

I don't even know where to start with that.



That would make it go lean until the PCM tried to correct for it. It would more than likely set a code, but not always. I'd expect hesitation especially at throttle tip in and pinging / detonation that was intermittent.