Running rich since cat back.

[GU357]

Hey.

Ive noticed the inside of my muffler has a fair bit of soot.
which is a sign of running rich i assume.

When the car first starts up, and i put my hand behind the tip and smell my hand later its got that fuelly smell.

could it just be that the soot is building up during warm up, or is it more likely the cat back has caused it to run richer all the time?

[oopoc]

First off that soot is normal, most places blacken the visible inside of the muffler so you don't notice. Secondly the fuel smell is a Honda trait, Honda generally tunes the engine to run very rich at idle (almost to the point of starving itself of air) if you give it a bit of throttle and more than just condensation comes out the exhaust, then you have something a miss. But the blackening of the exhaust is normal, sometimes for a while after having a new catback/muffler installed they blow some of the spot out as the air is now less restricted and therefore flows faster. And the fuel smell, drive around for a while with the windows down and ac off. If you smell it more than just idle then you may have a problem( or maby it's just the tune)

Hope this helps

[GU357]

i figured the smell was most likely just an idle/warm up thing.

ill ask my friend to follow me and see if he can smell anything.
just curious is a fuel smell is normal if im flooring it?
i wont be flooring it but im just wandering if it would be normal to have that smell as my friends cars have a fuel smell when they "floor it"
but i didnt think that it was an engine problem just the intake not keeping up with the injectors or something.

[oopoc]

just wandering if it would be normal to have that smell as my friends cars have a fuel smell when they "floor it"
but i didnt think that it was an engine problem just the intake not keeping up with the injectors or something.
so what you saying is you friends car has a fuel smelling ..... Smell, when they sink there boot in? In that case I would be inclined to check the timing (maby valves opening up too quick) and spark plugs (not getting enough spark and not burning all the mixture). But then again I used to have a mate with a 180sx apocalyptic turbo, decat, no resonator and a cannon. Thing always smelt like fuel and spewed out clouds of muck. So it may also depend on what they have done to the car. It could also be something as simple as the throttle setup. My old civic you put your foot down most of the way (90%) and the throttle was fully open then you push the other 10 and it can't open the throttle more but it injects more fuel (confused the absolute f*ck outta me)

[GU357]

Oh its my car i was talking abt but i was just curious as to whether mine would/should stink like that if i floored it.

[oopoc]

Seriously doubt it. My del sol wreaks of fuel at idle (specialy when cold) and it runs perfect (perfect for 120xxxkms) kinda a bummer with the roof off tho.

[GU357]

ahh ok, thanks for clearing that up. was affraid of having to get it retuned or something :S
my mates rx8 got a defect notice then they shoved a sniffer up their, he had to get a retune to run leaner thing overheated and cracked.
but thats a rotary

[oopoc]

ahh ok, thanks for clearing that up. was affraid of having to get it retuned or something :S

Were here to help


my mates rx8 got a defect notice then they shoved a sniffer up their, he had to get a retune to run leaner thing overheated and cracked.
but thats a rotary

Ah rotaries, munch munch pistons for lunch

[GU357]

Good stuff.

btw its We're, returning the favor :D

[oopoc]

Ah poop (obviously English isn't my strong suit) thanks.

[GU357]

haha thats probably the only help i could of provided u with lol.

[mugen_ctr]

its normal for any car to run slightly rich after wacking on a minor mods such as cat back an pod... But u shouldn't be smelling it at all on idle as what the other dude described... Not even my car is that bad with mods LOL, if its smelling on idle, than u have a bigger problem...

If ur finding its chewing fuel alot more as u drive, than try a ecu reset, an see if it helps

And if not, than look at the O2 sensor, might be stuffed....

If u want to make the most of the mods, than a tune is recommended

[hayashi_1986]

Were here to help



Ah rotaries, munch munch pistons for lunch

Rotaries don't have pistons lol

[senna]

Rotaries don't have pistons lol

I think he means Rotary motors eat Piston motors for lunch....I disagree but i think thats what he's getting at...

OP - did you change the cat when you did the exhaust or just the section after the cat? Is the new exhaust greatly larger than the original? Sometimes when the exhaust is much larger the gas velocity is increased which in turn results in the catalytic converter taking longer to heat up and burn off any excess fuel.

On the other hand, if you changed the cat to a high flow unit then there is a good chance that it simply isn't working as efficiently as the original cat at lower temperatures.

[oopoc]

I think he means Rotary motors eat Piston motors for lunch....I disagree but i think thats what he's getting at...

What I was getting at is with the rotary engine cycle they make much more power from the same size engine as a conventional piston engine. And therefore beat them in most things.

And yes after installing a cat back with the higher exhaust velocity even the stock catalytic converter takes longer to warm up as it doesn't get more exhaust but it doesn't stay as long. And from the factory Honda tune there engines to run rich at idle, and with even the stock cat not warming up as quick and therefore not working as well as it could you get your fuel smell at idle. I'm not here to lecture you on how Honda tune their engines, so how about instead of saying nah your wrong put something useful in I.e. be constructive

[senna]

Ummm, i'm pretty sure my second paragraph was being helpful and constructive...

The first bit wasn't a dig, it was simply saying i don't like rotary engines as much as i like Piston Engines...

[oopoc]

Sorry Senna i didn't mean you in particular, it's just a trend I've noticed with 'Honda mechanics' my first paragraph was in reply to you the the second was help with a little vent mixed it. But I agree with not liking rotarys as much as piston driven engines, seriously why would you build an engine where the rotor/piston can't handle constant running. While rotary engines may run for a long time, the corners of the rotors usually last a week or so giving you the distinctive rotary smell because the fuel isn't propperly kept away from the exiting exhaust. (think its something along those lines, not a rotary mechanic)

[senna]

All good man, quoting faux par - or something like that.... :thumbsup:

Yeah, apex seals - rotary achilles tendon

[hayashi_1986]

Expensive engines to maintain and not many experienced mechanics to build/rebuild them.

On another note, we don't know what he's done with the car. OP, can you fill us in with the mods you've slapped on to the car? That might help a bit in diagnosing the issue further. So in addition to the catback, did you have an intake or header installed? Pod filter? The ECU should re learn over time and adjust to these modifications, but the stock ECU can only re tune itself to a point. It will still run rich like all stock units to prevent piston failure (fuel keeps them cool). My EG use to blow black soot all over the arse of my car but never had any issues with fuel mileage, or any other mechanical issue for that matter. It did reek of fuel after hitting Vtec a few times. Totally normal. I had IHE on the car with a stupidly large cannon before. All that being less than restrictive will generally let the car breathe better, and consequently it'll also spit out a lot more excess fuel/soot/carbon deposits due to less walls/baffling in the new catback as opposed to stock.

[oopoc]

On another note, we don't know what he's done with the car. OP, can you fill us in with the mods you've slapped on to the car? That might help a bit in diagnosing the issue further. So in addition to the catback, did you have an intake or header installed? Pod filter? The ECU should re learn over time and adjust to these modifications, but the stock ECU can only re tune itself to a point. It will still run rich like all stock units to prevent piston failure (fuel keeps them cool). My EG use to blow black soot all over the arse of my car but never had any issues with fuel mileage, or any other mechanical issue for that matter. It did reek of fuel after hitting Vtec a few times. Totally normal. I had IHE on the car with a stupidly large cannon before. All that being less than restrictive will generally let the car breathe better, and consequently it'll also spit out a lot more excess fuel/soot/carbon deposits due to less walls/baffling in the new catback as opposed to stock.

I know why mine dose it, wouldn't have a clue about the exhaust past the cat. But I've a oem 4-2-1 headder and the cheapest cat I could get (roadworthy purpose) I have a 3" short ram and that's it for now. I don't think my car works very well which is why mine smells. But I'm sure it's just because his stock cat isn't warming up as quick as it used to and therefore letting the smell thru. Honestly i don't see the problem at idle but if his friend smells it following him, then we have a whole new kettle of fish

[hayashi_1986]

I know why mine dose it, wouldn't have a clue about the exhaust past the cat. But I've a oem 4-2-1 headder and the cheapest cat I could get (roadworthy purpose) I have a 3" short ram and that's it for now. I don't think my car works very well which is why mine smells. But I'm sure it's just because his stock cat isn't warming up as quick as it used to and therefore letting the smell thru. Honestly i don't see the problem at idle but if his friend smells it following him, then we have a whole new kettle of fish

I always attributed that issue to having an old engine like the d16y1 i had with 300k kms on the clock. I had the smell too, but not like a fresh fuel smell. I reckon it's normal operation of the engine in this case. Unless there's a fuel leak somewhere producing that fresh fuel smell that i mentioned. We'll wait for the OP to post his set up if anything.

[curtis265]

Some good info here guys

IT's quite normal to run rich. Stock tunes are generally a bit rich and the ECU adds more fuel to deal with the extra air flow (i think)

my prelude runs sickeningly rich and smells of fuel when u vtak it.

doesn't smell fuelly at idle tho (unless cold)

[hayashi_1986]

Some good info here guys

IT's quite normal to run rich. Stock tunes are generally a bit rich and the ECU adds more fuel to deal with the extra air flow (i think)

my prelude runs sickeningly rich and smells of fuel when u vtak it.

doesn't smell fuelly at idle tho (unless cold)

I'd say we have a winner...but if he's driving it normally, and his mate behind him can smell the car without stepping on vtec...that might be another issue that oopoc mentioned.

[dougie_504]

Reset your ECU.

New cat-backs do smell a bit until they're broken in.

Soot is normal!

[cihanvtec]

When the car first starts up, and i put my hand behind the tip and smell my hand later its got that fuelly smell

pretty sure any car would have a fuelly smell if u put ur hand over the exhaust them smell it.. its normal man my old civic used to do it aswell!!

[curtis265]

cold cat = cat taht doesn't work = fuelly smell on your hand when u finger your car

[GU357]

I've had the catback for ages. Stock headers and cat tho. With a apexi Sri pod intake.
So i waited a while before posting this so the new cat back smell is gone.
I had the same scoffed muffler on stock exhaust and didn't notice much soot till the rest of it was upgraded to a 2.25 inch.
I'll Fred it whit tonight maybe and ask my mate if it smells.

[stndrd]

If after resetting your ecu, you are still having issues with over fueling, I would be running a voltage test on both your o2 sensor and coolant temp sensor. The coolant temp sensor is just as vital as all the other sensors involved with fuel mapping, as it is telling the ecu how cold/hot the engine is and the ecu adds or reduces fuel acordingly in conjuction with the inputs from other sensors. Also remember that if you are checking this while the car is warming up, all cars run richer until they are operating temp, then the mixtures get leaned out to the operating temp afr

[GU357]

Alright thanks. That's the kinda thing I'm looking for thanks