Questions tagged [exhaust]

Questions about Exhaust systems, Catalytic Converters and Headers/Manifolds

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16
votes
3answers
12k views

How can I tell if I have bad cats?

No, not that cat! Catalytic converters - or "cats" - have a nasty habit of failing with age. What are the symptoms associated with a cat that's gone bad? Are there any tests that could definitively ...
37
votes
3answers
354k views

What does a water like drop coming out of the exhaust of the car signify?

Sometimes while driving in the traffic, I come across a car or two which would be dripping water-like drop from it's exhaust steadily in a break of 4-5 seconds. I tried to ask a couple of people at ...
4
votes
3answers
150k views

Excessive water dripping from exhaust

This question is similar: What does a water like drop coming out of the exhaust of the car signify? But it sounds like the water should be in small amounts, and only when the car has not been driving ...
25
votes
11answers
193k views

What is the best way to remove a stuck/rusted exhaust bolt?

I'm trying to disassemble the exhaust system on a 2000-2003 Nissan Maxima and I'm having trouble removing one last bolt. It's got a 14mm head and its just plain STUCK. I've tried soaking it overnight ...
11
votes
3answers
20k views

Is the catalytic converter broken? An odd rope is coming out of the exhaust pipe

Old Volvo GL 440 and this is coming out of the exhaust pipe. No noise, all working fine but this cosmetic thing: does it mean that the exhaust gases are now not well filtered out? Does this mean that ...
4
votes
3answers
36k views

How hot does an exhaust manifold get?

If I want to use a non-contact infrared thermometer to read the temperature of each cylinder at the exhaust port during idle, how high of a reading should the thermometer be able to handle?
12
votes
1answer
7k views

What are the tell tale signs of a catalytic converter that might be going bad?

I've owned two vehicles whose catalytic converters were recalled due two a couple of reasons: one being the quality of the CC and the other being a reduction in power due to a material building up and ...
7
votes
1answer
3k views

Why no exhaust gas turbine generator in hybrid vehicles?

I found something interesting on Wikipedia today: a hybrid turbocharger. This is a device that charges a battery with an exhaust gas turbine, and at the same time operates an air compressor using the ...
4
votes
1answer
5k views

Car Stalls When Coming to a Stop

Make: Chevy Model: Cavalier (4 cyl.) Automatic Year: 1993 Miles: 230K Normally my Cavalier drives just fine without problems. However, if I drive for 45+ minutes then it will sputter and stall out ...
32
votes
7answers
10k views

What is the point of the exhaust?

I was thinking today, what is the actual point of an exhaust? Why can't we just have a pipe going out the front of a car instead of taking all the gases to the back of the car? I can only see ...
28
votes
2answers
22k views

Why do two-stroke engine exhaust pipes look so strange?

Two stroke gasoline engine exhaust pipes are shaped strange. They expand into a wide diameter and then shrink down to a very small diameter where the exhaust gasses emerge into the environment. - ...
16
votes
5answers
45k views

When car is standing still, I smell Diesel exhaust. Why?

In my 2003 Opel Vectra, the cabin air smells of Diesel exhaust while stopped at e.g. a red light. The exhaust smell goes away when driving, and it also doesn't come back if I turn the ventilation off ...
11
votes
1answer
241 views

What Can I Learn From Exhaust Manifold Temps?

I was wondering what I can learn from the temperatures on the individual exhaust pipes coming out of each cylinder. The question is general, and my specific example is on my 98 Mazda 626 GF 2L. Last ...
12
votes
2answers
2k views

Can (possible) exhaust system damage cause random misfires?

2001 Honda Prelude SH. About three weeks ago while travelling 10-15 mph I pulled off the side of a dirt road to park and it turns out there was a row of a few railroad ties laying in the grass there....
12
votes
2answers
4k views

What is this yellow powder on my exhaust manifold?

I took off the heat shield from the exhaust manifold on my 2003 Nissan Primera while looking for an exhaust leak, and I noticed this yellowish poweder / dust on it: Any ideas what it is? EDIT ...
11
votes
2answers
1k views

Performance Exhaust — what, how, why?

I've seen performance exhaust pipes on sale for cars and motorcycles, and my questions are these: What does it do? (better performance [and how so?]? better mileage? cooler sounds?) Is/how is it ...
7
votes
2answers
1k views

Exhaust Backpressure and Its Impact on LTFT Values

This is a follow-up from my initial question which can be found here : LTFT and STFT values are off and don't make sense. Car : BMW 2015 F10 M5 Modifications : Eisenmann Race Catback Exhaust, ...
7
votes
1answer
787 views

Locating the O2 sensors and the cat along the exhaust

I gather that the upstream O2 sensor is the one right in the center of this picture. I also gather that the catalytic converter (the "cat") is the bulbous part of the exhaust right behind this sensor. ...
5
votes
1answer
2k views

Car feels like it's filling up with fumes

I bought a used 2000 volvo s80 with around 93k on the odometer. I was driving the other day and I felt sort of sick. At first I thought it was some dirt on the floor that got into the air. But upon ...
5
votes
3answers
3k views

straight pipes and carb rejetting?

I have a 1984 Honda GL 1200 standard wing and I am going to put straight pipes on it, however some forums say I will need to upjet the carbs, and others say I will not. Has anyone on this site ever ...
3
votes
1answer
2k views

What could be causing a distinct exhaust drone in a tight band around 3250 rpms on a 2004 Subaru WRX?

EDIT: Additional information provided by LovelyWife(TM) - listening outside the car, she has proclaimed that the rattle / buzz / drone / resonance is coming from the front of the car and sounds like ...
3
votes
3answers
2k views

Can Exhaust leaks be repaired by welding?

I have some small leaks(few mm) in my manifold and down pipe. As mine is a rare US manufactured car(civic vti 99) and I'm in uk, mechanic said it will be quite difficult to find the part. I aksed ...
3
votes
1answer
211 views

How should I diagnose an exhaust “howl” when descending through 3200 rpms?

As mentioned previously, I have a 2004 WRX wagon with a stainless Prodrive circular-tip axle-back installed around 2006. Lately, the weather has been nice enough to drive with the windows open and I'...
3
votes
1answer
311 views

Could this be the source of an exhaust leak

I originnaly thought my exhaust leak in my 93' miata was from the exhaust manifold headers as there was some soot on the heat shield but after removing it and looking at the down pipe I see this piece ...
2
votes
1answer
6k views

Rusty exhaust manifolds

Most of the engine on my 2007 V6 Tacoma is in a really good shape but both exhaust manifolds coming out of the engine block are really rusty. Q1: Is that a reason to worry or replace them, provided ...
2
votes
3answers
10k views

Can exhaust smell like coolant without it being a blown head gasket?

2005 honda civic ex, my coolant smells like exhaust, and I have been magically losing coolant/overheating the past month. It seems slow though, because it lasted 3 weeks between the last coolant ...
2
votes
2answers
2k views

Grey smoke when idling 1999 GMC Suburban, coolant system pressure loss

The most recent update is at the bottom. This looks interesting. The Smoke I'm confident the smoke is from burning oil. It's slightly blue, absolutely not white. If the engine is warm and I am ...
1
vote
3answers
129 views

What is exhaust gas recirculation?

From what I understand, EGR is used to reduce the temperature of combustion without increasing the amount of fuel injected to reduce NOx emission. This is done by reducing the oxygen percentage ...