Running rich since cat back.

**hayashi_1986** · 16-03-2012 03:20 AM

Originally Posted by oopoc

Were here to help

Ah rotaries, munch munch pistons for lunch

Rotaries don't have pistons lol

**senna** · 16-03-2012 07:30 AM

Originally Posted by hayashi_1986

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** · 16-03-2012 08:51 AM

Originally Posted by senna

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** · 16-03-2012 08:55 AM

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** · 16-03-2012 09:02 AM

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** · 16-03-2012 09:06 AM

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

Yeah, apex seals - rotary achilles tendon

**hayashi_1986** · 16-03-2012 09:55 AM

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** · 16-03-2012 10:05 AM

Originally Posted by hayashi_1986

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** · 16-03-2012 10:52 AM

Originally Posted by oopoc

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** · 16-03-2012 11:00 AM

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** · 16-03-2012 01:10 PM

Originally Posted by 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)

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.