Exhaust smells rich..? not good mpg

[SLOsClipse]

So to me the engines exhaust smells rich. It reminds me of my old civic's exhaust smell and it wouldn't pass smog cause it ran rich... What are some obvious newbie parts and tests I should be running?...

 

[Tyeler18]

A good run of the search feature is always a good start. Especially since there's a thread about this posted in earlier today, but-

Boost leak test
Compression test
Any codes need reading?
Leak down test
Full tune up

 

[2GFWDbeast]

i would replace the o2 sensor

 

[Tyeler18]

i would replace the o2 sensor

And if that doesn't fit the problem? That's just throwing money at it without actually finding out what the problem is. That's the worst way to diagnos a problem.

 

[Sik95TSI]

So to me the engines exhaust smells rich. It reminds me of my old civic's exhaust smell and it wouldn't pass smog cause it ran rich... What are some obvious newbie parts and tests I should be running?...

My TSI smells a little rich too, But it smells like nice clean Premium Fuel!

 

[hubbazoot]

And if that doesn't fit the problem? That's just throwing money at it without actually finding out what the problem is. That's the worst way to diagnos a problem.

The best solution would be to get a datalogger... you'll be using the crap out of it anyway if you really plan on getting into these cars.

If it's the O2 sensor, you'll see the O2 sensor voltage on it won't change even when you stomp on the gas or w/e.

Some possible solutions:
Ignition tune-up. New plugs and wires.
O2 Sensor (No real harm replacing, esp. if you don't know how old it is.)
Run some seafoam through the vacuum system (find a howto on youtube)
Run some seafoam through the gas.

 

[95_gsx_tuner]

Agreed, a datalogger will make your days in the DSM world less harsh. Also agree with the basic tune up. Plugs, Wires, Check O2 sensor (especially if its appears old and rusty), and Fuel Filter (most people overlook).

 

[hubbazoot]

Agreed, a datalogger will make your days in the DSM world less harsh. Also agree with the basic tune up. Plugs, Wires, Check O2 sensor (especially if its appears old and rusty), and Fuel Filter (most people overlook).

Right, forgot to mention fuel filter, but that would make him run lean...not rich.

A pocketlogger palm pilot will run you about $100 or so from someone, and they're fantastic. If you can, try to get one that has mmcd and dsmlogger on it, they both do different things better.

 

[SLOsClipse]

Right, forgot to mention fuel filter, but that would make him run lean...not rich.

A pocketlogger palm pilot will run you about $100 or so from someone, and they're fantastic. If you can, try to get one that has mmcd and dsmlogger on it, they both do different things better.

is there a good website that has these for sale? reliable sources?... or does anyone have one they're selling?... I for sure will get one! ps... sea foam?.. i look it up on youtube.. Sooo it just basically cleans ## system?.. i heard it's screwed pple's engines up before?..

 

[BleedBlak]

+1 on datalogging/tuning...i had a completely tuned engine by RRE...threw a rod due to failed HKS wg and ended up replacing it...new engine was running rich off of the old tune (goes to show that not everything even when identical runs/flows the same)...ran this way for about a year (never threw any codes just ran rich and oil was pungent smelling)...very bad mpg and exhaust smell could kill weeds ...it was time to smog again so i decided to tune again...i changed my fuel filter and put new plugs and wires before the tune along with new fluid changes on everything (to geth the most accurate tune i could)...tuned via open ECU...got the car back a few weeks ago and ive definately gained mpg and dont have to have my car hangin halfway out the garage when i warm it up...(plus the car runs 1000x better/stronger)..cost me $400 but couldve saved more than that on fuel if i would have done that right away...they even upgraded to a wally 255 and PTE 780's to make a better tune..

 

[Brandon Mau]

Another thing you could check if you could get your hands on a volt meter is the coolant temp. sensor this can make your car run rich also or not at all.

 

[BleedBlak]

How can the coolant sensor cause your car to run rich?? just curious...

 

[Cory-CR]

If sensor isn't giving the right reading it will make the car run in open-loop (not up to operating temp)

ECU thinks that car is cold and dumps fuel to get it heated up. Problem being that the engine may already be heated up so it's not accurately monitoring its AFR with the o2 sensor

 

[DSM_MAYHEM92]

The best solution would be to get a datalogger... you'll be using the crap out of it anyway if you really plan on getting into these cars.

If it's the O2 sensor, you'll see the O2 sensor voltage on it won't change even when you stomp on the gas or w/e.

Some possible solutions:
Ignition tune-up. New plugs and wires.
O2 Sensor (No real harm replacing, esp. if you don't know how old it is.)
Run some seafoam through the vacuum system (find a howto on youtube)
Run some seafoam through the gas.

Thats exactly what i would do...The seafoam is the best thing to clean the carbon build up on the o2 sensor or in ya fuel system injectors etc...So i highly recommend starting with that.Keep us informed.

 

[2gmummy]

I would check for exhaust leaks, exhaust leaks draw in air and can trick your o2 into thinking your running lean and therefore it would and more fuel to compensate causing you to run rich. Most of the time you can hear or see where the leak is coming from. Aslo i would clean your o2 sensor and spark plugs after you find the problem.

 

[Cory-CR]

Basically theres 1000 things that could cause you car to run rich. Most involve o2 sensor being bad, dirty, or wrong due to something else. Datalogger would be a good investment, though I've never used one myself and have been just fine. Bottom line, make sure you have a DVOM and a manual handy, and be ready to do some sensor probing.

 

[EclipticalGS]

Your front o2 sensor is probably bad. Replace it. Your coolant tep sensor could also be bad, replace it. Your MAF is probably dirty, clean it. If you have any exhaust leaks pre-front 02 sensor, make sure to correct those.

Once again, anyone saying that a boost leak could be his problem, It's not always that, and in this situation it most liekly isn't.

A boost leak at idle and cruise thats small will cause you to draw in un-metered air resulting in a lean condition. Under boost, it will cause a rich condition.

Lastly, if it is a big enough boost leak, it can cause your ecu to throw a ton of fuel at your motor, but he's talking about bad mpg just driving normally off boost.

 

[Cory-CR]

Your front o2 sensor is probably bad. Replace it. Your coolant tep sensor could also be bad, replace it. Your MAF is probably dirty, clean it. If you have any exhaust leaks pre-front 02 sensor, make sure to correct those.

Not everyone can just go throw stuff like that at their car though. Money's pretty tight sometimes. And if it's not it can become that way after too much of this.

Also an exhaust leak past the front O2 could have the same effect, it does not have to be in front of it. If there is a post-cat leak though, it is extremely unlikely that the leak is the issue.

 

[2GFWDbeast]

And if that doesn't fit the problem? That's just throwing money at it without actually finding out what the problem is. That's the worst way to diagnos a problem.

Really dude...... Seeing that a bad o2 could cause rich conditions and cause bad mpg. Its a pretty cheap fix. With what you said might as well tear the whole car down. Start with simple and cheap things. Boost leak test = money if he doesn't have one and a air compressor , leak down test = more money and if no air compressor ever more money.

 

[Cory-CR]

It's a cheap guess.

But a few cheap guesses if wrong can become expensive. Sure odds are it will help, but money is money.

 

[2GFWDbeast]

It's a cheap guess.

But a few cheap guesses if wrong can become expensive. Sure odds are it will help, but money is money.

well you have to start somewhere right???? What if the other things didn't work that would be a waste of money to. So he might as well leave the car how it is since everything is a waste of money right??

 

[EclipticalGS]

Not everyone can just go throw stuff like that at their car though. Money's pretty tight sometimes. And if it's not it can become that way after too much of this.

Also an exhaust leak past the front O2 could have the same effect, it does not have to be in front of it. If there is a post-cat leak though, it is extremely unlikely that the leak is the issue.

What are you talking about??

I told him to throw a $70 o2 sensor, a $15 coolant temp sensor, and a free cleaning of a MAF.

If he has an extra $100 a month to throw into his gas tank thats being burned for no reason, he should have $85 to correct his problem.

This is usually the case when people say they smell fuel, and their mpg is horrible.

Lastly, a post o2 housing leak won't cause shit unless its right at his o2 housing/ Downpipe connection, and even then It still won't do much. I had a leak their for the longest time and my o2 voltage and AFR was spot on.

If he hasn't replaced his 02 in the last 60,000 miles, Regardless if its working or not. A replacement should be made.

Simple.

After replacing these, he can top it off with a Boost leak test, and TPS/biss adjustment, and be back to running smoothly for $85.

 

[Cory-CR]

well you have to start somewhere right???? What if the other things didn't work that would be a waste of money to. So he might as well leave the car how it is since everything is a waste of money right??

I didn't say don't replace anything. I'm saying do some checks and tests on the sensors before you just throw new ones in. That's it.

And I don't know what you guys do for cash, but I don't make crap, and to me $85 isn't something I throw at the car until I know for a fact it will fix it.

I've worked in shops a long time, and I've replaced alot of things that weren't really the problem because of symptom diagnosis. I always test sensors before I throw new ones in their place because I'd rather fix the car with one new part than with 3.

 

[EclipticalGS]

I didn't say don't replace anything. I'm saying do some checks and tests on the sensors before you just throw new ones in. That's it.

And I don't know what you guys do for cash, but I don't make crap, and to me $85 isn't something I throw at the car until I know for a fact it will fix it.

I've worked in shops a long time, and I've replaced alot of things that weren't really the problem because of symptom diagnosis. I always test sensors before I throw new ones in their place because I'd rather fix the car with one new part than with 3.

I understand where your coming from, but to someone who doesn;t own a multimeter, or circuit probe, also doesn't have the means to check the sensors.

That is where we come in, to tell him the possible causes. There are only about 6 things that can cause this issue.

None of them are as expensive as the money he's burning out his tailpipe.

 

[DSM_MAYHEM92]

I would start by changing the o2 ecliptical is right on that part they should be changed around 60k miles anyways...that would be the first thing i would start with regardless then work my way to other possibly problems just like is said with everyone else's replies.But i would put my money on it being a exhaust leak or o2 sensor bad.I had the same problem and it was the o2 sensor.You can sometimes take them off and clean them only depending on the age of it.